*{box-sizing:border-box;margin:0;padding:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif}
:root{
  /* Slightly warm dark - easier on the eyes for long study sessions */
  --bg:#08080b;--surface:#111115;--surface2:#18181d;--surface3:#222228;
  --border:#222228;--border2:#38383f;
  --blue:#3b82f6;--blue-dim:rgba(59,130,246,.12);--blue-border:rgba(59,130,246,.35);
  --purple:#a855f7;--purple-dim:rgba(168,85,247,.12);
  --green:#22c55e;--green-dim:rgba(34,197,94,.12);--green-border:rgba(34,197,94,.35);
  --red:#ef4444;--red-dim:rgba(239,68,68,.12);--red-border:rgba(239,68,68,.35);
  --orange:#f59e0b;--orange-dim:rgba(245,158,11,.12);--orange-border:rgba(245,158,11,.35);
  --cyan:#06b6d4;--cyan-dim:rgba(6,182,212,.12);
  --text:#ededef;--text2:#9898a4;--text3:#5e5e6a;
  --r4:6px;--r6:8px;--r8:12px;--r12:16px;
  --read-width:860px; /* comfortable reading column */
}
html{-webkit-text-size-adjust:100%}
body{background:var(--bg);color:var(--text);height:100vh;display:flex;flex-direction:column;overflow:hidden;-webkit-font-smoothing:antialiased;font-size:16px;line-height:1.5}
/* Respect reduced-motion */
@media(prefers-reduced-motion:reduce){*{animation-duration:.01ms!important;transition-duration:.01ms!important}}
/* Accessible focus ring */
:focus-visible{outline:2px solid var(--blue);outline-offset:2px;border-radius:4px}

/* TOP BAR */
#topbar{display:flex;align-items:center;gap:12px;padding:0 20px;height:60px;background:var(--surface);border-bottom:1px solid var(--border);flex-shrink:0;position:sticky;top:0;z-index:50}
#topbar .logo{font-size:16px;font-weight:800;color:var(--blue);letter-spacing:-.3px}
#topbar .logo span{color:var(--text2);font-weight:500;font-size:12px;margin-left:8px}
.spacer{flex:1}
.tb-badge{padding:6px 12px;border-radius:20px;font-size:12px;font-weight:700;background:var(--orange-dim);border:1px solid var(--orange-border);color:var(--orange)}

/* LAYOUT */
#layout{display:flex;flex:1;overflow:hidden}

/* SIDEBAR (Desktop) / BOTTOM NAV (Mobile) */
#sidebar{width:232px;flex-shrink:0;background:var(--surface);border-right:1px solid var(--border);display:flex;flex-direction:column;overflow-y:auto;padding:10px 0}
.sb-section{padding:14px 16px 6px;font-size:10px;font-weight:700;color:var(--text3);text-transform:uppercase;letter-spacing:1.2px}
.sb-item{display:flex;align-items:center;gap:10px;padding:9px 14px;margin:1px 10px;border-radius:var(--r8);border:none;background:transparent;color:var(--text2);font-size:13.5px;font-weight:500;cursor:pointer;width:calc(100% - 20px);text-align:left;transition:background .15s,color .15s;min-height:44px}
.sb-item:hover{background:var(--surface2);color:var(--text)}
a.sb-item{text-decoration:none}
.sb-item.active{background:var(--blue-dim);color:var(--blue);font-weight:700}
.sb-item .ic{font-size:17px;width:22px;text-align:center;flex-shrink:0}
.sb-item .label{flex:1;line-height:1.3}
.sb-item .cnt{font-size:10px;padding:2px 7px;border-radius:10px;background:var(--surface3);color:var(--text3);font-weight:600;flex-shrink:0}
.sb-item.active .cnt{background:rgba(59,130,246,.18);color:var(--blue)}
.sb-divider{height:1px;background:var(--border);margin:8px 14px}

/* MAIN */
#main{flex:1;overflow:hidden;display:flex;flex-direction:column;background:var(--bg)}
#content{flex:1;overflow-y:auto;-webkit-overflow-scrolling:touch;padding:clamp(20px,3vw,36px) clamp(20px,4vw,48px);scroll-behavior:smooth}
#content::-webkit-scrollbar{width:5px}
#content::-webkit-scrollbar-thumb{background:var(--border2);border-radius:3px}
#content::-webkit-scrollbar-track{background:transparent}
.view{display:none}.view.active{display:block}
@keyframes slideUp{from{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}

/* ═══ NOTES ═══ */
.note-doc{max-width:1050px;margin:0 auto}

/* Title card - sets the context before diving in */
.note-title{padding:32px 28px 24px;background:linear-gradient(135deg,rgba(59,130,246,.08),rgba(168,85,247,.05));border:1px solid var(--border2);border-radius:var(--r12);margin-bottom:28px}
.note-title h1{font-size:24px;font-weight:800;color:var(--blue);margin-bottom:6px;letter-spacing:-.5px}
.note-title .sub{font-size:13.5px;color:var(--text2);line-height:1.5}
.note-title .tags{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}
.tag{padding:4px 12px;border-radius:20px;font-size:11.5px;font-weight:600;letter-spacing:.2px}
.tag-blue{background:var(--blue-dim);border:1px solid var(--blue-border);color:var(--blue)}
.tag-orange{background:var(--orange-dim);border:1px solid var(--orange-border);color:var(--orange)}
.tag-purple{background:var(--purple-dim);border:1px solid rgba(168,85,247,.3);color:var(--purple)}

/* Section headings - chapter-style, readable, not aggressive */
.n-h1{font-size:17px;font-weight:700;color:var(--blue);padding:10px 16px;margin:32px 0 14px;background:var(--blue-dim);border-left:3px solid var(--blue);border-radius:0 var(--r6) var(--r6) 0;letter-spacing:-.1px;line-height:1.4}
.n-h2{font-size:14.5px;font-weight:700;color:var(--purple);padding:8px 14px;margin:22px 0 10px;background:var(--purple-dim);border-left:2px solid var(--purple);border-radius:0 var(--r6) var(--r6) 0;letter-spacing:-.1px;line-height:1.4}
.n-h3{font-size:13px;font-weight:700;color:var(--text2);margin:16px 0 6px;padding:0 2px;text-transform:uppercase;letter-spacing:.5px}

/* Body text - comfortable study reading */
.n-p{font-size:15.5px;line-height:1.8;color:var(--text);margin:10px 0}
.n-val{display:inline;padding:2px 7px;border-radius:4px;background:var(--orange-dim);color:var(--orange);font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;font-size:13px;font-weight:600}

/* Callout boxes - important info, not alarming */
.n-crit,.n-warn,.n-info,.n-ok{display:flex;gap:12px;align-items:flex-start;border-radius:var(--r8);padding:14px 16px;margin:14px 0;border:1px solid}
.n-crit{background:rgba(239,68,68,.08);border-color:rgba(239,68,68,.25)}
.n-crit .icon{font-size:18px;color:var(--red);flex-shrink:0;margin-top:1px}
.n-crit .body{font-size:14px;color:var(--text);line-height:1.7}
.n-warn{background:rgba(245,158,11,.05);border-color:rgba(245,158,11,.15)}
.n-warn .icon{font-size:18px;color:var(--orange);flex-shrink:0;margin-top:1px}
.n-warn .body{font-size:14px;color:var(--text);line-height:1.7}
.n-info{background:rgba(59,130,246,.06);border-color:rgba(59,130,246,.15)}
.n-info .icon{font-size:18px;color:var(--blue);flex-shrink:0;margin-top:1px}
.n-info .body{font-size:14px;color:var(--text);line-height:1.7}
.n-ok{background:rgba(34,197,94,.06);border-color:rgba(34,197,94,.15)}
.n-ok .icon{font-size:18px;color:var(--green);flex-shrink:0;margin-top:1px}
.n-ok .body{font-size:14px;color:var(--text);line-height:1.7}
.n-crit .body strong{color:var(--red);font-weight:700}
.n-warn .body strong{color:var(--orange);font-weight:700}
.n-info .body strong{color:var(--blue);font-weight:700}
.n-ok .body strong{color:var(--green);font-weight:700}

/* Lists - clean, scannable */
.n-list{margin:12px 0;list-style:none;padding:0}
.n-list li{padding:5px 0 5px 24px;font-size:15px;line-height:1.7;color:var(--text);position:relative}
.n-list li::before{content:'\25B8';color:var(--blue);font-size:14px;position:absolute;left:4px;top:6px;line-height:1}
.n-list li strong{color:#fff;font-weight:600}
.n-list li em{color:var(--orange);font-style:normal;font-weight:600}

/* Cards & Grid */
.n-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:14px 0}
.n-grid-3{display:grid;grid-template-columns:1fr 1fr 1fr;gap:14px;margin:14px 0}
.n-card{background:var(--surface2);border:1px solid var(--border2);border-radius:var(--r12);padding:18px;transition:border-color .2s,transform .2s,box-shadow .2s}
.n-card:hover{transform:translateY(-3px);border-color:var(--border2);box-shadow:0 10px 24px rgba(0,0,0,.2)}
.n-card .card-title{font-size:11px;font-weight:700;color:var(--text3);text-transform:uppercase;letter-spacing:.8px;margin-bottom:10px}
.n-card .card-val{font-size:24px;font-weight:800;color:var(--blue);margin-bottom:6px}
.n-card .card-desc{font-size:13.5px;color:var(--text2);line-height:1.6}

/* Table - clean academic style */
.n-table{width:100%;border-collapse:collapse;margin:14px 0;font-size:13.5px}
.n-table th{background:var(--surface3);padding:10px 14px;text-align:left;font-size:11px;font-weight:700;color:var(--text2);text-transform:uppercase;letter-spacing:.5px;border-bottom:1px solid var(--border2)}
.n-table td{padding:11px 14px;border-bottom:1px solid var(--border);color:var(--text);line-height:1.6}
.n-table tr:last-child td{border-bottom:none}
.n-table tr:hover td{background:rgba(255,255,255,.03)}
.n-table .hl{color:var(--orange);font-weight:600}
.n-table .ok{color:var(--green);font-weight:600}
.n-table .bad{color:var(--red);font-weight:600}

/* Formula - monospace focus box */
.n-formula{background:var(--surface3);border:1px solid var(--border2);border-radius:var(--r8);padding:18px 20px;margin:14px 0;font-family:ui-monospace,SFMono-Regular,monospace;font-size:15px;color:var(--cyan);text-align:center}
.n-formula .label{font-family:-apple-system,sans-serif;font-size:11.5px;color:rgba(255, 255, 255, 0.55);margin-top:8px;letter-spacing:.3px}

/* Steps - numbered procedure */
.n-steps{margin:12px 0;counter-reset:step;list-style:none;padding:0}
.n-steps li{padding:7px 0 7px 38px;font-size:15px;line-height:1.7;color:var(--text);counter-increment:step;position:relative}
.n-steps li::before{content:counter(step);background:var(--blue);color:#fff;font-size:11px;font-weight:800;width:22px;height:22px;border-radius:50%;display:inline-flex;align-items:center;justify-content:center;position:absolute;left:0;top:9px}
.n-steps li strong{color:#fff;font-weight:600}

/* Section jump anchors */
.note-anchors{display:flex;flex-wrap:wrap;gap:7px;padding:14px 16px;margin-bottom:20px;background:var(--surface2);border:1px solid var(--border);border-radius:var(--r12)}
.note-anchors span{font-size:10px;color:var(--text3);font-weight:700;text-transform:uppercase;letter-spacing:.8px;width:100%;margin-bottom:4px}
.anc-btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:5px 13px;border-radius:20px;border:1px solid var(--border2);background:var(--surface3);color:var(--text2);font-size:12.5px;font-weight:600;cursor:pointer;transition:border-color .2s,color .2s,background .2s}
.anc-btn:hover{border-color:var(--blue);color:var(--blue);background:var(--blue-dim)}
.anc-btn:active{transform:scale(0.95)}

/* ═══ QUIZ ═══ */
#quiz-home{max-width:900px}
.quiz-topic-header{padding:24px;margin-bottom:24px;background:linear-gradient(135deg,rgba(34,197,94,.1),rgba(59,130,246,.08));border:1px solid var(--green-border);border-radius:var(--r12);display:flex;align-items:center;gap:20px;box-shadow:0 4px 16px rgba(0,0,0,.15)}
.quiz-topic-header .icon{font-size:36px;transition:transform .2s cubic-bezier(0.16,1,0.3,1)}
.quiz-topic-header:hover .icon{transform:scale(1.15) rotate(-5deg)}
.quiz-topic-header h2{font-size:22px;font-weight:800;color:var(--green);letter-spacing:-.5px}
.quiz-topic-header p{font-size:14px;color:var(--text2);margin-top:4px}
.quiz-topic-header .total{margin-left:auto;text-align:center;flex-shrink:0}
.quiz-topic-header .total .num{font-size:36px;font-weight:800;color:var(--green)}
.quiz-topic-header .total .lbl{font-size:12px;color:var(--text3);text-transform:uppercase;letter-spacing:.5px;margin-top:2px}
.qcat-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:12px;margin-bottom:20px}
.qcat-btn{display:flex;flex-direction:column;gap:6px;padding:16px 20px;background:var(--surface2);border:1px solid var(--border);border-radius:var(--r12);cursor:pointer;text-align:left;transition:background .2s,border-color .2s,color .2s,transform .2s,opacity .2s;min-height:80px;box-shadow:0 2px 6px rgba(0,0,0,.1)}
.qcat-btn:hover{border-color:var(--blue);background:var(--surface3);transform:translateY(-4px) scale(1.02);box-shadow:0 12px 24px rgba(0,0,0,.25)}
.qcat-btn:active{transform:translateY(0) scale(0.96)}
.qcat-btn.all-btn{border-color:var(--green-border);background:var(--green-dim)}
.qcat-btn.all-btn:hover{border-color:var(--green);background:rgba(34,197,94,.2)}
.qcat-btn .cat-name{font-size:14px;font-weight:700;color:var(--text)}
.qcat-btn.all-btn .cat-name{color:var(--green)}
.qcat-btn .cat-count{font-size:12px;color:var(--text3)}
.qcat-btn.all-btn .cat-count{color:rgba(34,197,94,.8)}
.qcat-btn .cat-bar{height:4px;background:var(--border);border-radius:2px;margin-top:8px;overflow:hidden}
.qcat-btn .cat-fill{height:100%;background:var(--blue);border-radius:2px;transition:width .4s cubic-bezier(0.16,1,0.3,1)}
.qcat-btn.all-btn .cat-fill{background:var(--green)}

/* Quiz active */
#quiz-active{display:none;max-width:720px;margin:0 auto}
.quiz-progress{margin-bottom:24px}
.quiz-progress-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}
.quiz-progress-top .qnum{font-size:14px;font-weight:600;color:var(--text2)}
.quiz-progress-top .score{font-size:14px;font-weight:800;color:var(--green)}
.quiz-progress-top .cat-tag{font-size:12px;padding:4px 10px;border-radius:12px;background:var(--blue-dim);border:1px solid var(--blue-border);color:var(--blue);font-weight:600}
.qbar{height:6px;background:var(--surface3);border-radius:3px;overflow:hidden}
.qfill{height:100%;background:linear-gradient(90deg,var(--blue),var(--purple));border-radius:3px;transition:width .3s cubic-bezier(0.16,1,0.3,1)}
/* Quiz card - clean study mode, distraction-free */
.quiz-card{background:var(--surface);border:1px solid var(--border2);border-radius:var(--r12);overflow:hidden;box-shadow:0 4px 20px rgba(0,0,0,.2)}
.quiz-q-area{padding:28px 24px 18px}
.quiz-q-area .qtext{font-size:17px;font-weight:600;line-height:1.7;color:var(--text)}
.quiz-opts{display:flex;flex-direction:column;gap:10px;padding:14px 24px 20px}
.qopt{display:flex;align-items:center;gap:14px;padding:14px 18px;background:var(--surface2);border:1px solid var(--border);border-radius:var(--r12);cursor:pointer;text-align:left;width:100%;transition:border-color .15s,background .15s;min-height:56px}
.qopt:hover:not(:disabled){background:var(--surface3);border-color:var(--border2)}
.qopt:active:not(:disabled){transform:scale(0.98)}
.qopt .opt-letter{width:28px;height:28px;border-radius:50%;background:var(--surface3);border:1px solid var(--border2);font-size:12px;font-weight:800;color:var(--text2);display:flex;align-items:center;justify-content:center;flex-shrink:0}
.qopt .opt-text{font-size:14.5px;color:var(--text);line-height:1.6;flex:1;text-align:left;font-weight:500}
.qopt.correct{background:rgba(34,197,94,.08)!important;border-color:rgba(34,197,94,.4)!important}
.qopt.correct .opt-letter{background:var(--green);border-color:var(--green);color:#fff}
.qopt.correct .opt-text{color:#a7f3c0!important;font-weight:600}
.qopt.wrong{background:rgba(239,68,68,.08)!important;border-color:rgba(239,68,68,.4)!important;animation:shake 0.4s cubic-bezier(0.36,0.07,0.19,0.97) both}
@keyframes shake{10%,90%{transform:translate3d(-2px,0,0)}20%,80%{transform:translate3d(4px,0,0)}30%,50%,70%{transform:translate3d(-6px,0,0)}40%,60%{transform:translate3d(6px,0,0)}}
.qopt.wrong .opt-letter{background:var(--red);border-color:var(--red);color:#fff}
.qopt.wrong .opt-text{color:#fca5a5!important}
.qopt:disabled{cursor:default}
/* Explanation box - the key study element */
.quiz-exp{margin:0 24px 16px;padding:14px 18px;background:rgba(59,130,246,.07);border:1px solid rgba(59,130,246,.2);border-radius:var(--r8);font-size:13.5px;color:#c4d9fe;line-height:1.75;display:none}
.quiz-exp.show{display:block}
.quiz-exp strong{color:#fff;font-weight:700}
.quiz-actions{display:flex;align-items:center;justify-content:space-between;padding:14px 22px;background:var(--surface2);border-top:1px solid var(--border)}
.quiz-actions .hint{font-size:13px;color:var(--text3);font-weight:500;transition:opacity 0.3s}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:0 24px;border-radius:var(--r8);border:none;font-size:14px;font-weight:700;cursor:pointer;transition:background .15s,border-color .15s,color .15s,transform .15s;box-shadow:0 2px 4px rgba(0,0,0,.2)}
.btn:active{transform:scale(0.95)}
.btn-primary{background:var(--blue);color:#fff}
.btn-primary:hover{background:#2563eb;box-shadow:0 6px 16px rgba(59,130,246,.4);transform:translateY(-2px)}
.btn-ghost{background:var(--surface3);border:1px solid var(--border2);color:var(--text2);box-shadow:none}
.btn-ghost:hover{background:var(--surface2);color:var(--text);transform:translateY(-2px)}
.btn-green{background:var(--green);color:#fff}
.btn-green:hover{background:#16a34a;box-shadow:0 6px 16px rgba(34,197,94,.4);transform:translateY(-2px)}
.score-screen{text-align:center;padding:48px 32px;background:var(--surface);border:1px solid var(--border2);border-radius:var(--r12);max-width:460px;margin:0 auto;box-shadow:0 8px 30px rgba(0,0,0,.3)}
.score-emoji{font-size:64px;margin-bottom:20px;}
.score-pct{font-size:56px;font-weight:800;margin-bottom:8px;color:var(--blue);letter-spacing:-1px;}
.score-sub{font-size:15px;color:var(--text2);margin-bottom:32px;line-height:1.5;}
.score-breakdown{display:grid;grid-template-columns:1fr 1fr 1fr;gap:12px;margin-bottom:32px;}
.score-stat{background:var(--surface2);border:1px solid var(--border);border-radius:var(--r8);padding:16px 12px;transition:transform 0.3s cubic-bezier(0.16,1,0.3,1)}
.score-stat:hover{transform:translateY(-4px) scale(1.05)}
.score-stat .n{font-size:28px;font-weight:800;color:var(--text)}
.score-stat .l{font-size:12px;color:var(--text3);margin-top:4px;text-transform:uppercase;letter-spacing:.5px;font-weight:600}
.score-actions{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;}

/* Welcome */
.welcome{max-width:800px;margin:0 auto;text-align:center;padding-top:48px}
.welcome h1{font-size:36px;font-weight:800;color:var(--text);margin-bottom:12px;letter-spacing:-1px}
.welcome h1 span{color:var(--blue)}
.welcome p{font-size:16px;color:var(--text2);line-height:1.6;max-width:540px;margin:0 auto 40px}
.welcome-grid{display:grid;grid-template-columns:1fr 1fr;gap:20px;text-align:left}
.welcome-card{padding:24px;background:var(--surface);border:1px solid var(--border);border-radius:var(--r12);cursor:pointer;transition:background .2s,border-color .2s,color .2s,transform .2s,opacity .2s;box-shadow:0 4px 12px rgba(0,0,0,.1)}
.welcome-card:hover{border-color:var(--blue);transform:translateY(-8px) scale(1.02);box-shadow:0 20px 40px rgba(59,130,246,.2), 0 0 20px rgba(59,130,246,.1)}
.welcome-card .wc-icon{font-size:32px;margin-bottom:16px;transition:background .2s,border-color .2s,color .2s,transform .2s,opacity .2s}
.welcome-card:hover .wc-icon{transform:translateY(-6px);filter:drop-shadow(0 8px 12px rgba(59,130,246,0.6))}
.welcome-card h3{font-size:18px;font-weight:700;color:var(--text);margin-bottom:8px}
.welcome-card p{font-size:14px;color:var(--text2);line-height:1.6}
.welcome-card .wc-badge{display:inline-block;margin-top:16px;padding:4px 12px;border-radius:20px;font-size:12px;font-weight:700;background:var(--blue-dim);border:1px solid var(--blue-border);color:var(--blue)}

/* ─── MOBILE TOPIC STRIP (shows above notes on mobile only) ─── */
.mobile-topic-strip{display:none;overflow-x:auto;white-space:nowrap;padding:0 0 12px;margin-bottom:8px;scrollbar-width:none}
.mobile-topic-strip::-webkit-scrollbar{display:none}
.mts-btn{display:inline-flex;align-items:center;gap:5px;padding:10px 12px;min-height:44px;border-radius:20px;border:1px solid var(--border2);background:var(--surface2);color:var(--text3);font-size:11px;font-weight:600;cursor:pointer;white-space:nowrap;transition:background .2s,border-color .2s,color .2s,transform .2s;opacity:0.5;margin-right:6px}
.mts-btn:hover{opacity:0.85;border-color:var(--border)}
.mts-btn.mts-active{opacity:1;background:var(--blue-dim);border-color:var(--blue);color:var(--blue)}
@media(max-width:768px){.mobile-topic-strip{display:block}.topic-footer-nav{flex-wrap:wrap;gap:8px}.tfn-btn{max-width:100%;flex:1 1 calc(50% - 14px)}.tfn-center{width:100%;order:3;padding-top:4px}}

/* ─── TOPIC SIDEBAR LIST ─── */
#topic-side-list{display:none;overflow-y:auto;flex:1;padding:4px 0 16px;border-top:1px solid var(--border);margin-top:4px;min-height:0}
.tl-item{display:flex;align-items:center;gap:8px;padding:6px 10px;min-height:44px;margin:1px 6px;border-radius:var(--r8);border:none;background:transparent;cursor:pointer;width:calc(100% - 12px);text-align:left;transition:background .15s,border-color .15s,color .15s;opacity:0.35;font-size:12px;color:var(--text2);line-height:1.3}
.tl-item:hover{opacity:0.75;background:var(--surface2);color:var(--text)}
.tl-item.tl-active{opacity:1;background:var(--blue-dim);color:var(--blue);font-weight:700}
.tl-item .tl-ic{font-size:13px;width:17px;flex-shrink:0}
.tl-item .tl-label{flex:1;font-size:11.5px}
.tl-item .tl-num{font-size:9px;font-weight:800;opacity:0.5;flex-shrink:0;font-family:monospace}
.tl-item.tl-active .tl-num{opacity:0.7;color:var(--blue)}


.tin-arrow{display:flex;align-items:center;justify-content:center;width:34px;height:34px;border-radius:var(--r8);border:1px solid var(--border2);background:var(--surface2);color:var(--text2);font-size:14px;cursor:pointer;transition:background .15s,border-color .15s,color .15s;flex-shrink:0;text-decoration:none}
.tin-arrow:hover{border-color:var(--blue);color:var(--blue);background:var(--blue-dim)}
.tin-arrow.disabled{opacity:0.3;cursor:not-allowed;pointer-events:none}
.tin-pill{flex:1;display:flex;align-items:center;justify-content:center;gap:7px;height:34px;border-radius:var(--r8);border:1px solid var(--border2);background:var(--surface2);color:var(--text2);font-size:12.5px;font-weight:600;cursor:pointer;transition:background .15s,border-color .15s,color .15s;user-select:none}
.tin-pill:hover{border-color:var(--blue);color:var(--blue);background:var(--blue-dim)}
.tin-pill.open{border-color:var(--blue);color:var(--blue);background:var(--blue-dim);border-bottom-left-radius:0;border-bottom-right-radius:0}
.tin-pill .tin-ic{font-size:15px}
.tin-pill .tin-arrow-icon{font-size:9px;opacity:.6;transition:transform .2s}
.tin-pill.open .tin-arrow-icon{transform:rotate(180deg)}
.tin-inner{position:relative}
.tin-dropdown{display:none;position:absolute;top:100%;left:42px;right:42px;background:var(--surface2);border:1px solid var(--blue);border-top:none;border-bottom-left-radius:var(--r8);border-bottom-right-radius:var(--r8);z-index:200;max-height:320px;overflow-y:auto;box-shadow:0 8px 24px rgba(0,0,0,.3)}
.tin-dropdown.open{display:block}
.tin-dropdown::-webkit-scrollbar{width:4px}
.tin-dropdown::-webkit-scrollbar-thumb{background:var(--border2);border-radius:2px}
.tin-drop-item{display:flex;align-items:center;gap:10px;padding:8px 14px;cursor:pointer;font-size:12.5px;color:var(--text2);transition:background .1s}
.tin-drop-item:hover{background:var(--surface3);color:var(--text)}
.tin-drop-item.tin-active{background:var(--blue-dim);color:var(--blue);font-weight:700}
.tin-drop-item .tin-num{font-size:10px;font-family:monospace;opacity:0.5;margin-left:auto;flex-shrink:0}
.tin-drop-item.tin-active .tin-num{opacity:0.7}

/* ─── QUIZ BANK ─── */
#view-quiz-bank{max-width:720px}
.qb-header{margin-bottom:28px}
.qb-header h2{font-size:20px;font-weight:800;color:var(--text);letter-spacing:-.3px;margin-bottom:6px}
.qb-header p{font-size:13.5px;color:var(--text2)}
.qb-row{margin-bottom:22px}
.qb-label{font-size:11px;font-weight:800;color:var(--text3);text-transform:uppercase;letter-spacing:1px;margin-bottom:10px}
/* Section toggle */
.qb-seg{display:flex;gap:0;border:1px solid var(--border2);border-radius:var(--r8);overflow:hidden;width:fit-content}
.qb-seg-btn{padding:9px 24px;min-height:44px;border:none;background:var(--surface2);color:var(--text2);font-size:13px;font-weight:600;cursor:pointer;transition:background .15s,border-color .15s,color .15s;border-right:1px solid var(--border2)}
.qb-seg-btn:last-child{border-right:none}
.qb-seg-btn:hover:not(.disabled){background:var(--surface3);color:var(--text)}
.qb-seg-btn.active{background:var(--blue);color:#fff}
.qb-seg-btn.disabled{opacity:0.35;cursor:not-allowed}
/* Topic dropdown */
.qb-dropdown{position:relative}
.qb-dropdown-trigger{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:10px 16px;background:var(--surface2);border:1px solid var(--border2);border-radius:var(--r8);cursor:pointer;transition:border-color .15s;min-width:min(280px,100%);font-size:13.5px;color:var(--text)}
.qb-dropdown-trigger:hover{border-color:var(--blue)}
.qb-dropdown-trigger.open{border-color:var(--blue);border-bottom-color:transparent;border-radius:var(--r8) var(--r8) 0 0}
.qb-dropdown-trigger .arrow{font-size:10px;color:var(--text3);transition:transform .2s}
.qb-dropdown-trigger.open .arrow{transform:rotate(180deg)}
.qb-dropdown-panel{display:none;position:absolute;top:100%;left:0;right:0;background:var(--surface2);border:1px solid var(--blue);border-top:none;border-radius:0 0 var(--r8) var(--r8);z-index:200;max-height:200px;overflow-y:auto;box-shadow:0 8px 24px rgba(0,0,0,.3)}
.qb-dropdown-panel.open{display:block}
.qb-dropdown-panel::-webkit-scrollbar{width:4px}
.qb-dropdown-panel::-webkit-scrollbar-thumb{background:var(--border2);border-radius:2px}
.qb-drop-item{display:flex;align-items:center;gap:10px;padding:9px 14px;cursor:pointer;transition:background .1s;font-size:13px;color:var(--text2)}
.qb-drop-item:hover{background:var(--surface3);color:var(--text)}
.qb-drop-item.checked{color:var(--blue)}
.qb-drop-item .chk{width:14px;height:14px;border-radius:3px;border:1.5px solid var(--border2);flex-shrink:0;display:flex;align-items:center;justify-content:center;font-size:10px;transition:background .15s,border-color .15s,color .15s}
.qb-drop-item.checked .chk{background:var(--blue);border-color:var(--blue);color:#fff}
.qb-drop-divider{height:1px;background:var(--border);margin:4px 0}
.qb-drop-all{font-weight:700;color:var(--text)}
/* Category pills - full names */
.qb-cats{display:flex;flex-wrap:wrap;gap:7px}
.qb-cat-pill{padding:6px 14px;border-radius:20px;border:1px solid var(--border2);background:var(--surface2);color:var(--text2);font-size:12.5px;font-weight:500;cursor:pointer;transition:background .15s,border-color .15s,color .15s;white-space:nowrap}
.qb-cat-pill:hover{border-color:var(--border2);color:var(--text);background:var(--surface3)}
.qb-cat-pill.active{background:var(--blue-dim);border-color:var(--blue-border);color:var(--blue);font-weight:700}
.qb-cat-pill.all-cat.active{background:var(--green-dim);border-color:var(--green-border);color:var(--green)}
.qb-cats-empty{font-size:13px;color:var(--text3);padding:4px 0}
/* Count */
.qb-count-row{display:flex;gap:8px;flex-wrap:wrap}
.qb-cnt-btn{padding:8px 20px;border-radius:var(--r8);border:1px solid var(--border2);background:var(--surface2);color:var(--text2);font-size:13px;font-weight:700;cursor:pointer;transition:background .15s,border-color .15s,color .15s;min-height:44px}
.qb-cnt-btn:hover{color:var(--text);background:var(--surface3)}
.qb-cnt-btn.active{background:var(--purple-dim);border-color:var(--purple-b);color:var(--purple)}
/* Footer */
.qb-footer{display:flex;align-items:center;gap:16px;margin-top:28px;padding-top:20px;border-top:1px solid var(--border)}
.qb-preview{font-size:13px;color:var(--text2);flex:1;line-height:1.6}
.qb-preview strong{color:var(--text);font-weight:700}
.qb-start{padding:0 32px;height:46px;background:var(--blue);color:#fff;border:none;border-radius:var(--r8);font-size:14px;font-weight:700;cursor:pointer;transition:background .2s,transform .2s;white-space:nowrap}
.qb-start:hover{background:#2563eb;transform:translateY(-2px);box-shadow:0 6px 16px rgba(59,130,246,.35)}
.qb-start:disabled{opacity:.35;cursor:not-allowed;transform:none;box-shadow:none}

/* ─── BOTTOM TOPIC FOOTER NAV ─── */
.topic-footer-nav{display:flex;align-items:stretch;gap:10px;margin-top:48px;padding:20px 0 8px;border-top:1px solid var(--border)}
.tfn-btn{flex:1;display:flex;flex-direction:column;gap:3px;padding:14px 18px;background:var(--surface2);border:1px solid var(--border2);border-radius:var(--r12);cursor:pointer;transition:background .15s,border-color .15s,color .15s,transform .15s;max-width:calc(50% - 22px);text-align:left}
.tfn-btn:hover{border-color:var(--blue);transform:translateY(-2px);box-shadow:0 8px 20px rgba(0,0,0,.2)}
.tfn-btn.tfn-next{text-align:right;margin-left:auto}
.tfn-btn.disabled{opacity:0.2;cursor:not-allowed;pointer-events:none}
.tfn-btn.disabled:hover{transform:none;box-shadow:none}
.tfn-dir{font-size:10px;color:var(--text3);font-weight:700;text-transform:uppercase;letter-spacing:.5px}
.tfn-name{font-size:12.5px;color:var(--text);font-weight:600;line-height:1.4;margin-top:3px}
.tfn-center{display:flex;align-items:center;justify-content:center;font-size:11px;color:var(--text3);padding:0 4px;flex-shrink:0}


/* Hamburger Menu Defaults */
#mobile-menu-btn {
  display: none;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  color: var(--text);
  padding: 6px;
  margin-right: 12px;
  margin-left: -4px;
  cursor: pointer;
  border-radius: var(--r8);
  transition: background 0.2s;
}
#mobile-menu-btn:hover { background: rgba(255,255,255,0.05); }
#sidebar-overlay { display: none; }

/* MOBILE RESPONSIVE OVERRIDES */
@media (max-width: 768px) {
  #mobile-menu-btn { display: inline-flex; }
  
  /* Slide-out Sidebar Morph */
  #sidebar {
    will-change: transform;
    position: fixed;
    top: 56px; /* below topbar */
    left: 0;
    bottom: 0;
    width: 260px;
    height: calc(100svh - 56px);
    z-index: 1000;
    transform: translateX(-280px);
    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: none;
  }
  #sidebar.open {
    transform: translateX(0);
    box-shadow: 4px 0 24px rgba(0,0,0,0.5);
  }
  
  #sidebar-overlay {
    display: block;
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.6);
    
    z-index: 999;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
  }
  #sidebar-overlay.open {
    opacity: 1;
    pointer-events: auto;
  }
  
  #main { padding-bottom: 0; }
  #content { padding: 16px; }
  
  /* Topbar */
  #topbar { padding: 0 16px; height: 56px; }
  
  /* Grids to 1 column */
  .welcome-grid, .n-grid, .n-grid-3, .qcat-grid { grid-template-columns: 1fr; gap: 10px; }
  /* Full-width reading on mobile */
  .note-doc { max-width: 100%; margin: 0; }
  
  /* Adjust typography & padding for mobile */
  .welcome h1 { font-size: 28px; }
  .welcome p { font-size: 14px; margin-bottom: 24px; }
  .welcome-card { padding: 16px; }
  
  .note-title { padding: 24px 16px; }
  .note-title h1 { font-size: 22px; }
  
  .quiz-topic-header { flex-direction: column; text-align: center; gap: 12px; padding: 20px 16px; }
  .quiz-topic-header .total { margin-left: 0; margin-top: 8px; }
  
  .quiz-q-area { padding: 20px 16px 12px; }
  .quiz-opts { padding: 12px 16px 16px; }
  .quiz-actions { padding: 12px 16px; }
  
  .n-table { font-size: 13px; display: block; overflow-x: auto; white-space: nowrap; }
  .n-table th, .n-table td { padding: 10px 12px; }
  /* Overflow fixes for quiz/score screens */
  .score-screen, .duo-score-container { max-width: 100%; padding: 24px 16px; gap: 16px; border: none; border-radius: 0; box-shadow: none; }
  .duo-score-ill { font-size: 64px; }
  .duo-score-header h2 { font-size: 24px; }
  .duo-score-stat-box .n { font-size: 22px; }
  #quiz-active { max-width: 100%; }
  #quiz-home, #view-quiz-bank { max-width: 100%; }
  .n-formula { overflow-x: auto; }

  /* ── Surveyor Q&A mobile ── */
  #view-sq-landing > div,
  #view-sq-grid > div { padding: 0; }
  #view-sq-landing > div > div:first-child { padding: 20px 0 16px; }
  #view-sq-landing > div > div:first-child h1 { font-size: 20px; }
  .sq-card { padding: 14px; }
  .sq-q { font-size: 14px; }
  .sq-a { padding: 12px; font-size: 13px; }
  .sq-bullet { flex-wrap: wrap; gap: 4px; }
  .sq-label { font-size: 12px; }
  .sq-bullet-text { font-size: 13px; }
  .sq-para { font-size: 13px; }
  .sq-badge-surveyor, .sq-badge-topic { font-size: 10px; padding: 3px 8px; }
  .sq-header { flex-wrap: wrap; }
}

.sb-spacer{flex:1}

/* ─── SVG ICONS ─── */
.svg-ic {
  width: 1.2em;
  height: 1.2em;
  stroke: currentColor;
  fill: none;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  vertical-align: text-bottom;
}

/* ─── GAMIFIED SCORE SCREEN (DUOLINGO STYLE) ─── */
.duo-score-container {
    text-align: center;
    padding: 40px 32px;
    background: var(--surface);
    border: 1px solid var(--border2);
    border-radius: var(--r12);
    max-width: 480px;
    margin: 0 auto;
    box-shadow: 0 12px 40px rgba(0,0,0,0.25);
    
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 24px;
}
.duo-score-ill {
    font-size: 80px;
    line-height: 1;
    
    filter: drop-shadow(0 10px 15px rgba(0,0,0,0.3));
    margin-bottom: -10px;
}
.duo-score-header h2 {
    font-size: 32px;
    font-weight: 900;
    margin: 0 0 8px 0;
    letter-spacing: -0.5px;
}
.duo-score-header p {
    font-size: 16px;
    color: var(--text2);
    margin: 0;
}
.duo-score-stats {
    display: flex;
    gap: 12px;
    width: 100%;
}
.duo-score-stat-box {
    flex: 1;
    background: var(--surface2);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: 16px 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    transition: transform 0.2s;
}

.duo-score-stat-box .n {
    font-size: 28px;
    font-weight: 800;
}
.duo-score-stat-box .l {
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text2);
}
.duo-score-actions {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-top: 8px;
}
.duo-btn {
    width: 100%;
    padding: 16px;
    font-size: 18px;
    font-weight: 800;
    border-radius: 16px;
    border: none;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: background 0.2s, color 0.2s, border-color 0.2s, opacity 0.2s;
}
.duo-btn-primary {
    background: var(--green);
    color: #fff;
    box-shadow: 0 6px 0 #1b873f;
}
.duo-btn-primary:active {
    transform: translateY(6px);
    box-shadow: 0 0 0 #1b873f;
}
.duo-btn-primary.needs-practice {
    background: var(--orange);
    box-shadow: 0 6px 0 #b35900;
}
.duo-btn-primary.needs-practice:active {
    transform: translateY(6px);
    box-shadow: 0 0 0 #b35900;
}
.duo-btn-secondary {
    background: transparent;
    color: var(--text2);
    border: 2px solid var(--border2);
}
.duo-btn-secondary:hover {
    background: var(--surface2);
    color: var(--text);
}
.duo-btn-secondary:active {
    background: var(--border2);
}

/* ── Notes Search ─────────────────────────────────────── */
.search-results-dropdown {
    display: none;
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    right: 0;
    background: var(--surface);
    border: 1px solid var(--border2);
    border-radius: 14px;
    z-index: 200;
    max-height: 340px;
    overflow-y: auto;
    box-shadow: 0 16px 48px rgba(0,0,0,0.65), 0 4px 12px rgba(0,0,0,0.4);
    overscroll-behavior: contain;
}
.sr-item {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 11px 14px;
    cursor: pointer;
    border-bottom: 1px solid var(--border);
    transition: background 0.12s;
}
.sr-item:last-of-type { border-bottom: none; }
.sr-item:hover { background: var(--surface2); }
.sr-badge {
    flex-shrink: 0;
    font-size: 10px;
    font-weight: 700;
    background: var(--blue-dim);
    color: var(--blue);
    border: 1px solid var(--blue-border);
    border-radius: 6px;
    padding: 2px 7px;
    margin-top: 2px;
    letter-spacing: .3px;
}
.sr-content { flex: 1; min-width: 0; }
.sr-heading {
    font-size: 13px;
    font-weight: 600;
    color: var(--text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: 1.4;
}
.sr-mark {
    background: var(--blue-dim);
    color: var(--blue);
    border-radius: 3px;
    padding: 0 2px;
    font-style: normal;
}
.sr-snippet {
    font-size: 12px;
    color: var(--text2);
    margin-top: 3px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: 1.4;
}
.sr-empty, .sr-indexing {
    padding: 14px 16px;
    text-align: center;
    color: var(--text2);
    font-size: 13px;
}
.sr-indexing {
    border-top: 1px solid var(--border);
    font-size: 11px;
    color: var(--text3);
    padding: 8px 14px;
    text-align: left;
}
.sr-meta {
    font-size: 11px;
    color: var(--text3);
    margin-top: 2px;
    font-weight: 500;
}

/* ── Global search panel scrollbar ──────────────────────── */
.gsearch-scroll {
    overflow-y: auto;
    overscroll-behavior: contain;
}
.gsearch-scroll::-webkit-scrollbar,
.search-results-dropdown::-webkit-scrollbar {
    width: 4px;
}
.gsearch-scroll::-webkit-scrollbar-track,
.search-results-dropdown::-webkit-scrollbar-track {
    background: transparent;
    margin: 6px 0;
}
.gsearch-scroll::-webkit-scrollbar-thumb,
.search-results-dropdown::-webkit-scrollbar-thumb {
    background: var(--border2);
    border-radius: 4px;
}
.gsearch-scroll::-webkit-scrollbar-thumb:hover,
.search-results-dropdown::-webkit-scrollbar-thumb:hover {
    background: var(--text3);
}

/* ── Sidebar search filter dropdown ─────────────────────── */
.gsf-opt {
    display: block;
    width: 100%;
    padding: 9px 14px;
    background: transparent;
    border: none;
    color: var(--text2);
    font-size: 13px;
    font-weight: 500;
    text-align: left;
    cursor: pointer;
    transition: background 0.12s, color 0.12s;
}
.gsf-opt:hover {
    background: var(--surface2);
    color: var(--text);
}
.gsf-opt + .gsf-opt {
    border-top: 1px solid var(--border);
}

/* ═══════════════ SURVEYOR Q&A PREMIUM STYLING ═══════════════ */
.sq-landing-card:hover { border-color: var(--purple) !important; box-shadow: 0 20px 40px rgba(168,85,247,.2), 0 0 20px rgba(168,85,247,.1) !important; }
.sq-landing-card:hover .wc-icon { filter: drop-shadow(0 8px 12px rgba(168,85,247,0.6)) !important; }
.sq-back-btn { border-color: var(--purple) !important; color: var(--purple) !important; }
.sq-oral-card { background: linear-gradient(135deg, var(--surface) 60%, rgba(168,85,247,.08)); border-color: rgba(168,85,247,.35) !important; }
.sq-oral-card h3 { color: var(--purple); }
.sq-oral-card:hover { border-color: var(--purple) !important; box-shadow: 0 20px 40px rgba(168,85,247,.25), 0 0 24px rgba(168,85,247,.15) !important; background: linear-gradient(135deg, var(--surface) 40%, rgba(168,85,247,.14)) !important; }
.sq-oral-card:hover .wc-icon { filter: drop-shadow(0 8px 12px rgba(168,85,247,0.7)) !important; }
.sq-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--r12); padding: 20px; margin-bottom: 16px; box-shadow: 0 4px 12px rgba(0,0,0,0.05); transition: transform 0.2s, box-shadow 0.2s; }
.sq-card:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.08); }
.sq-header { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 12px; gap: 12px; }
.sq-badges { display: flex; gap: 8px; flex-wrap: wrap; }
.sq-badge-surveyor { background: var(--purple-dim); color: var(--purple); padding: 4px 10px; border-radius: 20px; font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.5px; }
.sq-badge-topic { background: var(--surface3); color: var(--text2); padding: 4px 10px; border-radius: 20px; font-size: 11px; font-weight: 600; }
.sq-q { font-size: 16px; font-weight: 700; color: var(--text); line-height: 1.5; margin-bottom: 16px; }
.sq-a { font-size: 14px; color: var(--text2); line-height: 1.6; background: var(--surface2); padding: 16px; border-radius: var(--r8); border-left: 4px solid var(--purple); }
.sq-bullet { display: flex; gap: 8px; align-items: baseline; padding: 5px 0; border-bottom: 1px solid var(--border); }
.sq-bullet:last-child { border-bottom: none; }
.sq-label { color: var(--purple); font-weight: 700; font-size: 13px; white-space: nowrap; flex-shrink: 0; }
.sq-bullet-text { color: var(--text2); }
.sq-numbered { display: flex; gap: 10px; align-items: baseline; padding: 5px 0; }
.sq-num { color: var(--orange); font-weight: 700; font-size: 13px; flex-shrink: 0; min-width: 20px; }
.sq-para { padding: 6px 0; color: var(--text2); }

/* ── Oral Scroll Hint ── */
@keyframes osh-enter { from{opacity:0;transform:translateX(-50%) translateY(24px)} to{opacity:1;transform:translateX(-50%) translateY(0)} }
@keyframes osh-exit  { to{opacity:0;transform:translateX(-50%) translateY(16px)} }
@keyframes osh-bounce{ 0%,100%{transform:translateY(0)} 50%{transform:translateY(5px)} }
@keyframes osh-pulse { 0%,100%{box-shadow:0 8px 28px rgba(168,85,247,0.5),0 0 0 0 rgba(168,85,247,0.5)} 60%{box-shadow:0 8px 28px rgba(168,85,247,0.5),0 0 0 10px rgba(168,85,247,0)} }
#oral-scroll-hint.osh-show { display:flex !important; animation: osh-enter 0.45s cubic-bezier(0.34,1.56,0.64,1) forwards; }
#oral-scroll-hint.osh-hide { animation: osh-exit 0.3s ease forwards; }
#osh-arrow { animation: osh-bounce 1.1s ease-in-out infinite; }
#osh-pill { animation: osh-pulse 2s ease-in-out infinite; }

.sq-surveyor-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--r12); padding: 20px; cursor: pointer; transition: transform 0.2s, border-color 0.2s; display: flex; flex-direction: column; gap: 8px; height: 100%; box-shadow: 0 4px 12px rgba(0,0,0,0.03); }
.sq-surveyor-card:hover { border-color: var(--orange); transform: translateY(-4px); box-shadow: 0 10px 20px rgba(245, 158, 11, 0.1); }
.sq-surveyor-name { font-size: 18px; font-weight: 800; color: var(--text); display: flex; align-items: center; gap: 8px; }
.sq-surveyor-stat { font-size: 13px; color: var(--text2); }

/* ══════════════════════════════════════════
   APP GUIDE
══════════════════════════════════════════ */
#guide-overlay { position:fixed; inset:0; z-index:9000; display:none; pointer-events:all; }

#guide-spotlight {
    position: fixed; z-index: 9001; pointer-events: none; display: none;
    border: 2px solid rgba(168,85,247,0.75);
    box-shadow: 0 0 0 9999px rgba(0,0,0,0.76), 0 0 0 5px rgba(168,85,247,0.12), 0 0 32px rgba(168,85,247,0.3);
}

#guide-tooltip {
    position: fixed; z-index: 9002; display: none;
    background: var(--surface);
    border: 1px solid var(--border2);
    border-radius: 16px;
    padding: 18px 20px 16px;
    width: min(300px, calc(100vw - 32px));
    box-shadow: 0 24px 64px rgba(0,0,0,0.65), 0 4px 16px rgba(0,0,0,0.3);
}
.guide-tt-header { display:flex; justify-content:space-between; align-items:center; margin-bottom:10px; }
.guide-tt-stepcount { font-size:11px; font-weight:700; color:var(--purple); text-transform:uppercase; letter-spacing:0.8px; }
.guide-tt-skip { background:none; border:none; color:var(--text3); font-size:11px; cursor:pointer; padding:0; font-family:inherit; }
.guide-tt-skip:hover { color:var(--text2); }
.guide-tt-title { font-size:15px; font-weight:800; color:var(--text); margin-bottom:7px; line-height:1.3; }
.guide-tt-body { font-size:13px; color:var(--text2); line-height:1.6; margin-bottom:16px; }
.guide-tt-footer { display:flex; align-items:center; justify-content:space-between; gap:12px; }
.guide-btn-next { background:var(--purple); border:none; color:#fff; padding:8px 18px; border-radius:8px; font-size:13px; font-weight:700; cursor:pointer; font-family:inherit; transition:opacity 0.15s, transform 0.15s; white-space:nowrap; }
.guide-btn-next:hover { opacity:0.85; transform:translateY(-1px); }

#guide-dots { display:flex; gap:5px; align-items:center; }
.guide-dot { width:6px; height:6px; border-radius:50%; background:var(--border2); transition:all 0.25s ease; flex-shrink:0; }
.guide-dot.active { width:18px; border-radius:4px; background:var(--purple); }

#guide-slide-wrap {
    position: fixed; inset: 0; z-index: 9001;
    background: rgba(0,0,0,0.9);
    backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
    align-items: center; justify-content: center;
    padding: 24px; box-sizing: border-box;
}
#guide-slide-card {
    background: var(--surface);
    border: 1px solid rgba(255,255,255,0.06);
    border-radius: 22px;
    padding: 36px 32px;
    max-width: 420px; width: 100%;
    box-shadow: 0 48px 96px rgba(0,0,0,0.6), 0 0 0 1px rgba(168,85,247,0.08);
}
.guide-btn-primary {
    display: block; width: 100%;
    padding: 13px 24px;
    background: var(--purple); border: none; border-radius: 10px;
    color: #fff; font-size: 15px; font-weight: 700; cursor: pointer;
    font-family: inherit; transition: opacity 0.15s, transform 0.15s;
    box-sizing: border-box;
}
.guide-btn-primary:hover { opacity:0.87; transform:translateY(-1px); }
.guide-btn-support {
    display: block; width: 100%; box-sizing: border-box;
    padding: 13px 24px;
    background: linear-gradient(135deg, rgba(168,85,247,1), rgba(139,60,220,1));
    border: none; border-radius: 10px;
    color: #fff; font-size: 15px; font-weight: 700; cursor: pointer;
    font-family: inherit; text-decoration: none; text-align: center;
    transition: opacity 0.15s, transform 0.15s;
    box-shadow: 0 6px 24px rgba(168,85,247,0.4);
}
.guide-btn-support:hover { opacity:0.88; transform:translateY(-1px); }
.guide-btn-text { background:none; border:none; color:var(--text3); font-size:13px; cursor:pointer; font-family:inherit; padding:0; }
.guide-btn-text:hover { color:var(--text2); text-decoration:underline; }
.guide-stat-box { background:var(--surface2); border:1px solid var(--border); border-radius:10px; padding:10px 14px; min-width:68px; }
.guide-stat-num { font-size:20px; font-weight:800; color:var(--purple); line-height:1; }
.guide-stat-lbl { font-size:11px; color:var(--text3); margin-top:3px; font-weight:600; text-transform:uppercase; letter-spacing:0.5px; }

#guide-relaunch-btn {
    width: 28px; height: 28px; border-radius: 50%;
    background: var(--surface2); border: 1.5px solid var(--border);
    color: var(--text2); font-size: 13px; font-weight: 700;
    cursor: pointer; display: flex; align-items: center; justify-content: center;
    flex-shrink: 0; transition: border-color 0.15s, color 0.15s;
}
#guide-relaunch-btn:hover { border-color: var(--purple); color: var(--purple); }

@media (max-width: 768px) {
    #guide-slide-card { padding: 28px 22px; }
    #guide-tooltip { width: min(280px, calc(100vw - 24px)); padding: 14px 16px 14px; }
    .guide-tt-body { font-size: 12.5px; margin-bottom: 12px; }
    /* Hide logo subtitle on mobile — prevents topbar overflow */
    .logo span { display: none; }
    /* Video tab segment: tighter padding so two buttons fit on small screens */
    .qb-seg-btn { padding: 9px 14px; }
    /* Score breakdown: 2 cols on mobile (3 cols at ~90px each is too tight) */
    .score-breakdown { grid-template-columns: 1fr 1fr; }
}

/* ── Floating video player — mobile layout ── */
@media (max-width: 600px) {
    /* Stack player on top, playlist scrollable below */
    .vid-float-inner { flex-direction: column; }
    .vid-float-player { flex: none; width: 100%; }
    .vid-float-sidebar {
        flex: 0 0 auto;
        border-left: none;
        border-top: 1px solid var(--border2);
        max-height: 36vh;
    }
    /* Use dvh so iOS browser chrome doesn't clip the bottom */
    .vid-float-box { max-height: 90dvh; }
    /* Bigger close button tap target */
    .vid-float-close {
        padding: 10px 16px;
        font-size: 18px;
        min-width: 44px;
        min-height: 44px;
        display: flex;
        align-items: center;
        justify-content: center;
    }
}

/* ── VIDEOS TAB STYLES ── */
.vid-lang-chips { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 12px; }
.vid-lang-chip {
    padding: 5px 12px;
    border-radius: 20px;
    border: 1px solid var(--border2);
    background: var(--surface2);
    color: var(--text3);
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.15s, color 0.15s;
}
.vid-lang-chip:hover { background: var(--surface); color: var(--text); }
.vid-lang-chip.active { background: var(--blue); color: #fff; border-color: var(--blue); }
.vid-list { display: flex; flex-direction: column; gap: 4px; }
.vid-list-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 11px 14px;
    border-radius: 10px;
    background: var(--surface2);
    border: 1px solid var(--border2);
    cursor: pointer;
    text-align: left;
    width: 100%;
    transition: background 0.15s;
}
.vid-list-item:hover { background: var(--surface); }
.vid-list-icon { color: var(--blue); font-size: 13px; flex-shrink: 0; }
.vid-list-label { font-size: 13px; font-weight: 600; color: var(--text); flex: 1; }
.vid-lang-badge {
    font-size: 10px;
    font-weight: 700;
    padding: 2px 7px;
    border-radius: 10px;
    background: rgba(59,130,246,0.12);
    color: var(--blue);
    flex-shrink: 0;
    letter-spacing: 0.03em;
}

/* Floating player */
.vid-float-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.65);
    z-index: 1200;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 16px;
}
.vid-float-box {
    background: var(--surface);
    border-radius: 14px;
    width: min(92vw, 920px);
    max-height: 85vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    box-shadow: 0 24px 64px rgba(0,0,0,0.55);
}
.vid-float-topbar {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding: 8px 10px;
    border-bottom: 1px solid var(--border2);
    flex-shrink: 0;
}
.vid-float-close {
    background: none;
    border: none;
    color: var(--text3);
    font-size: 16px;
    cursor: pointer;
    padding: 4px 8px;
    border-radius: 6px;
    line-height: 1;
}
.vid-float-close:hover { background: var(--surface2); color: var(--text); }
.vid-float-inner {
    display: flex;
    min-height: 0;
    flex: 1;
}
.vid-float-player {
    flex: 1 1 65%;
    display: flex;
    flex-direction: column;
    min-width: 0;
}
.vid-float-iframe-wrap {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    flex-shrink: 0;
}
.vid-float-iframe-wrap iframe {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    border: 0;
}
.vid-float-now-playing {
    padding: 10px 14px;
    font-size: 12px;
    font-weight: 600;
    color: var(--text);
    border-top: 1px solid var(--border2);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    flex-shrink: 0;
}
.vid-float-sidebar {
    flex: 0 0 35%;
    border-left: 1px solid var(--border2);
    overflow-y: auto;
    display: flex;
    flex-direction: column;
}
.vid-float-pl-item {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 11px 14px;
    cursor: pointer;
    border-bottom: 1px solid var(--border2);
    border-left: none;
    border-right: none;
    border-top: none;
    width: 100%;
    text-align: left;
    background: none;
    transition: background 0.15s;
}
.vid-float-pl-item:hover { background: var(--surface2); }
.vid-float-pl-item.active { background: rgba(59,130,246,0.1); }
.vid-float-pl-icon { color: var(--blue); font-size: 11px; flex-shrink: 0; margin-top: 2px; }
.vid-float-pl-label { font-size: 12px; font-weight: 600; color: var(--text); line-height: 1.4; }

/* ── NOTE DIAGRAMS ── */
.note-diagram-wrap {
    margin: 18px 0;
    text-align: center;
}
.note-diagram-wrap img {
    max-width: min(100%, 560px);
    max-height: 300px;
    width: auto;
    height: auto;
    display: block;
    margin: 0 auto;
    border-radius: 10px;
    border: 1px solid var(--border2);
    background: #fff;
    cursor: zoom-in;
    transition: box-shadow .2s;
}
.note-diagram-wrap img:hover {
    box-shadow: 0 4px 24px rgba(59,130,246,.25);
}
.note-diagram-wrap img.zoomed {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: auto;
    max-width: 95vw;
    max-height: 92vh;
    object-fit: contain;
    z-index: 9999;
    border-radius: 8px;
    cursor: zoom-out;
    box-shadow: 0 0 0 100vmax rgba(0,0,0,.88);
}
.note-diagram-cap {
    font-size: 12px;
    color: var(--text3, #888);
    margin-top: 6px;
    font-style: italic;
}
@media(max-width:600px){
    .note-diagram-wrap img { max-width: 100%; }
}