:root{--ink:#15243a;--muted:#607087;--line:#dbe3ec;--paper:#fff;--canvas:#eef3f7;--blue:#1057d4;--blue2:#083c9b;--aqua:#20c6a7;--amber:#ffb84d;--red:#c83b4b;--green:#167b63;--shadow:0 22px 55px rgba(26,48,79,.12);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;color:var(--ink);background:var(--canvas);font-size:16px}*{box-sizing:border-box}body{margin:0;min-height:100vh;background:radial-gradient(circle at 85% 5%,rgba(32,198,167,.12),transparent 27rem),var(--canvas)}button{font:inherit}.topbar{height:76px;display:grid;grid-template-columns:240px 1fr auto;gap:28px;align-items:center;padding:0 32px;background:#0d1d32;color:#fff;position:sticky;top:0;z-index:10}.brand{display:flex;gap:12px;align-items:center;color:#fff;text-decoration:none;font-size:1.1rem;letter-spacing:.02em}.mark{display:grid;place-items:center;width:38px;height:38px;border-radius:11px;background:var(--aqua);color:#09291f;font-size:.8rem;font-weight:900;letter-spacing:-.03em}.top-progress{display:flex;align-items:center;justify-content:center;gap:14px;font-size:.85rem;color:#c9d6e5}.progress-track{height:7px;width:min(32vw,360px);background:#32435b;border-radius:99px;overflow:hidden}.progress-track div{height:100%;width:0;background:linear-gradient(90deg,var(--aqua),#7cf5de);border-radius:inherit;transition:width .35s ease}.quiet-button{background:transparent;color:#c9d6e5;border:1px solid #45566d;border-radius:10px;padding:9px 13px;cursor:pointer}.quiet-button:hover{border-color:#8ea2ba;color:#fff}.shell{display:grid;grid-template-columns:290px minmax(0,900px);gap:34px;max-width:1280px;margin:auto;padding:34px}.rail{align-self:start;position:sticky;top:110px}.rail-heading{display:flex;flex-direction:column;padding:0 12px 16px}.rail-heading span,.eyebrow{font-size:.75rem;text-transform:uppercase;letter-spacing:.16em;color:var(--blue);font-weight:800}.rail-heading strong{font-size:1.05rem;margin-top:6px}.lesson-link{width:100%;display:grid;grid-template-columns:34px 1fr 22px;gap:10px;align-items:center;text-align:left;border:0;background:transparent;padding:11px 12px;border-radius:12px;color:#596a7f;cursor:pointer;margin:2px 0}.lesson-link:hover{background:#e4ebf2;color:var(--ink)}.lesson-link.active{background:#fff;color:var(--ink);box-shadow:0 8px 24px rgba(30,55,86,.08)}.lesson-link .num{display:grid;place-items:center;width:30px;height:30px;border:1px solid #c6d1dd;border-radius:50%;font-size:.78rem;font-weight:800}.lesson-link.done .num{background:var(--green);border-color:var(--green);color:#fff}.lesson-link .check{color:var(--green);font-weight:900}.lesson-link .label{font-size:.9rem;font-weight:700}.rail-note{margin-top:18px;padding:18px;background:#dfe8f0;border-radius:14px;display:flex;flex-direction:column;gap:6px;font-size:.85rem;line-height:1.45;color:#506174}.rail-note strong{color:var(--ink)}.workspace{min-width:0}.lesson-card{background:var(--paper);border:1px solid rgba(180,195,210,.7);border-radius:24px;box-shadow:var(--shadow);padding:clamp(26px,5vw,58px);min-height:710px}.lesson-card h1{font-family:Georgia,"Times New Roman",serif;font-size:clamp(2.2rem,5vw,4rem);line-height:1.02;letter-spacing:-.04em;margin:15px 0 18px;max-width:760px}.lesson-lead{font-size:1.15rem;line-height:1.7;color:#4f6175;max-width:720px;margin:0 0 32px}.concept-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:24px 0}.concept{border:1px solid var(--line);border-radius:15px;padding:18px;background:#f9fbfd}.concept .step{display:block;color:var(--blue);font-weight:900;font-size:.78rem;letter-spacing:.08em;margin-bottom:8px}.concept strong{display:block;margin-bottom:6px}.concept p,.tip p{margin:0;color:#5d6d80;line-height:1.5;font-size:.93rem}.tip{display:flex;gap:14px;padding:18px;border-left:4px solid var(--aqua);background:#effbf8;border-radius:0 12px 12px 0;margin:22px 0}.tip b{white-space:nowrap}.example{margin:20px 0;border:1px solid var(--line);border-radius:16px;overflow:hidden}.example-row{display:grid;grid-template-columns:115px 1fr;gap:12px;padding:15px 18px;border-top:1px solid var(--line);line-height:1.5}.example-row:first-child{border-top:0}.speaker{font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;font-weight:900;color:#76869a}.activity{margin-top:30px;padding-top:28px;border-top:1px solid var(--line)}.activity h2{font-size:1.25rem;margin:0 0 8px}.activity-instruction{color:var(--muted);margin:0 0 18px;line-height:1.55}.prompt{padding:19px 21px;background:#15243a;color:#fff;border-radius:15px;margin-bottom:16px;font-size:1.04rem;line-height:1.55}.choices{display:grid;gap:10px}.choice{display:flex;gap:13px;text-align:left;padding:15px 17px;border:1px solid #ccd7e2;border-radius:13px;background:#fff;color:var(--ink);cursor:pointer;line-height:1.45;transition:.15s ease}.choice:hover:not(:disabled){border-color:var(--blue);transform:translateY(-1px)}.choice .letter{flex:0 0 26px;height:26px;display:grid;place-items:center;border-radius:7px;background:#edf2f7;font-size:.76rem;font-weight:900}.choice.correct{border-color:var(--green);background:#effaf6}.choice.incorrect{border-color:var(--red);background:#fff3f4}.choice:disabled{cursor:default}.feedback{display:none;margin-top:14px;padding:17px;border-radius:13px;line-height:1.55}.feedback.show{display:block}.feedback.good{background:#e9f8f2;color:#125e4c}.feedback.try{background:#fff3e2;color:#704716}.feedback strong{display:block;margin-bottom:4px}.retry{margin-top:12px;border:1px solid currentColor;background:transparent;color:inherit;border-radius:9px;padding:8px 12px;cursor:pointer;font-weight:800}.lesson-actions{display:flex;justify-content:space-between;gap:12px;margin-top:34px}.primary,.secondary{border-radius:11px;padding:12px 17px;font-weight:800;cursor:pointer}.primary{border:0;background:var(--blue);color:#fff}.primary:hover:not(:disabled){background:var(--blue2)}.primary:disabled{background:#aebac8;cursor:not-allowed}.secondary{background:#fff;border:1px solid #c9d4df;color:var(--ink)}.match-list{display:grid;gap:11px}.match-row{display:grid;grid-template-columns:minmax(0,1fr) minmax(220px,.75fr);gap:12px;align-items:center}.match-row label{font-weight:750;line-height:1.35}.match-row select{width:100%;padding:12px;border:1px solid #c9d4df;border-radius:10px;background:#fff;color:var(--ink);font:inherit}.completion{display:grid;place-items:center;text-align:center;min-height:560px}.completion-badge{display:grid;place-items:center;width:90px;height:90px;border-radius:50%;background:var(--aqua);font-size:2.2rem;font-weight:900;color:#08362d;margin-bottom:25px}.completion h1{max-width:600px}.completion p{max-width:610px;color:var(--muted);font-size:1.1rem;line-height:1.7}.next-step-card{background:#10233c;color:white;border-radius:18px;padding:24px;text-align:left;margin:22px 0}.next-step-card span{display:block;color:#8ee8d5;font-size:.75rem;text-transform:uppercase;letter-spacing:.12em;font-weight:900;margin-bottom:9px}.next-step-card strong{font-size:1.06rem;line-height:1.55}.small{font-size:.82rem;color:var(--muted)}
.audio-lab{margin:28px 0 4px;padding:22px;background:linear-gradient(135deg,#0f2138,#173451);border-radius:18px;color:#fff}.audio-lab-head{display:flex;justify-content:space-between;gap:18px;align-items:end;margin-bottom:15px}.audio-lab h2{margin:0 0 4px;font-size:1.2rem}.audio-lab-head p{margin:0;color:#b9c9d9;font-size:.9rem}.audio-time{font-size:.75rem;color:#8ee8d5;font-weight:800;white-space:nowrap}.audio-examples{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}.audio-example{display:flex;flex-direction:column;min-width:0;border:1px solid #38536f;background:#142a43;border-radius:13px;padding:14px}.audio-example span{font-size:.72rem;text-transform:uppercase;letter-spacing:.09em;color:#8ee8d5;font-weight:900}.audio-example p{margin:8px 0 13px;color:#dce7f1;font-size:.87rem;line-height:1.45;flex:1}.play-audio{display:flex;align-items:center;justify-content:center;gap:8px;border:1px solid #5d7894;border-radius:9px;background:#203d5d;color:#fff;padding:9px 10px;cursor:pointer;font-weight:800}.play-audio:hover{background:#2b5075}.play-audio.playing{background:var(--aqua);border-color:var(--aqua);color:#082b23}.audio-status{min-height:1.2em;margin-top:10px;color:#b9c9d9;font-size:.78rem}
@media(max-width:850px){.topbar{grid-template-columns:1fr auto;padding:0 18px}.top-progress{display:none}.shell{display:block;padding:18px}.rail{position:static;margin-bottom:16px}.rail-heading,.rail-note{display:none}#lessonNav{display:flex;overflow-x:auto;gap:6px;padding-bottom:6px}.lesson-link{min-width:max-content;width:auto;grid-template-columns:30px 1fr 18px;padding:8px 10px}.lesson-card{min-height:auto;border-radius:18px;padding:26px 20px}.concept-grid,.audio-examples{grid-template-columns:1fr}.match-row{grid-template-columns:1fr}.lesson-actions{align-items:stretch}.primary,.secondary{flex:1}.example-row{grid-template-columns:85px 1fr}}
@media(max-width:480px){.quiet-button{font-size:0;padding:9px}.quiet-button:after{content:"Reset";font-size:.82rem}.lesson-card h1{font-size:2.35rem}.lesson-actions{flex-direction:column-reverse}.example-row{grid-template-columns:1fr;gap:4px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}