:root{--purple:#6d28d9;--dark:#5520ad;--ink:#251b35;--muted:#655b73;--line:#e3dced;--pale:#f3edff}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:#fff;color:var(--ink);font:16px/1.7 system-ui,sans-serif}a{color:var(--purple)}button,input,textarea,select{font:inherit}button,.button{background:var(--purple);color:#fff;border:0;border-radius:9px;padding:11px 20px;cursor:pointer;font-weight:650;text-decoration:none;display:inline-block;margin:12px 0}button:hover,.button:hover{background:var(--dark)}.secondary{background:var(--pale);color:var(--dark)}.secondary:hover{background:#e8dafa}button:disabled{opacity:.5;cursor:not-allowed}a:focus-visible,button:focus-visible,input:focus-visible,textarea:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--purple);outline-offset:4px}.skip{position:absolute;top:-100px}.skip:focus{top:8px;left:10px;background:white;padding:12px;z-index:10}header{padding:18px 5%;border-bottom:1px solid var(--line);display:flex;align-items:center;gap:28px;flex-wrap:wrap}.brand{font-size:30px;font-weight:800;letter-spacing:-1px;text-decoration:none}nav{display:flex;flex-wrap:wrap;gap:18px}nav a{text-decoration:none}header form{margin-left:auto}main{max-width:1080px;margin:auto;padding:40px 24px 70px}h1{font-size:clamp(30px,5vw,43px);line-height:1.18;letter-spacing:-1px}h2{font-size:25px;line-height:1.35}h3{font-size:20px}.eyebrow{color:var(--dark);font-size:12px;font-weight:750;text-transform:uppercase;letter-spacing:1.6px}.muted{color:var(--muted)}.grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px}.card{border:1px solid var(--line);border-radius:16px;padding:27px;margin-bottom:24px}.narrow{max-width:600px;margin:auto}.hero{background:var(--purple);color:white;padding:30px;border-radius:16px;margin-top:24px}.notice{border-left:4px solid var(--purple);background:var(--pale);padding:14px 18px}.error{border-left-color:#9a2241;background:#fff0f4}.tag{display:inline-block;background:var(--pale);color:var(--dark);padding:3px 11px;border-radius:30px;font-size:13px}.row{display:flex;gap:18px;align-items:center;flex-wrap:wrap}label{display:block;font-weight:650;margin:18px 0 7px}input:not([type=checkbox]),textarea,select{width:100%;padding:12px;border:1px solid #9688a8;background:white;color:var(--ink);border-radius:8px}textarea{min-height:155px}.check{font-weight:400}input[type=checkbox]{width:18px;height:18px;vertical-align:middle;margin-right:8px}audio,progress{width:100%;margin:15px 0;accent-color:var(--purple)}blockquote{margin:18px 0;background:var(--pale);border-left:4px solid var(--purple);padding:18px 22px}.exercise{padding:12px 0 24px;border-bottom:1px solid var(--line)}.steps{margin:24px 0}.steps a{background:var(--pale);padding:7px 12px;border-radius:6px}.module-list{list-style:none;padding:0}.module-list li{border-bottom:1px solid var(--line);padding:14px 0 22px}.table-wrap{overflow:auto}table{border-collapse:collapse;width:100%;text-align:left}td,th{padding:14px;border-bottom:1px solid var(--line)}.pre-line{white-space:pre-line}summary{cursor:pointer;color:var(--dark)}footer{text-align:center;color:var(--muted);padding:25px;border-top:1px solid var(--line);font-size:13px}[hidden]{display:none!important}@media(max-width:680px){.grid{grid-template-columns:1fr}header{padding:16px 20px;gap:14px}header form{margin:0}nav{gap:12px}main{padding:26px 18px 50px}.card,.hero{padding:20px}.row{gap:12px}td,th{padding:8px}}

.editor{min-height:650px;font:14px/1.5 monospace;white-space:pre;overflow:auto}header nav{flex-wrap:wrap}audio{max-width:100%}.pre-line{overflow-wrap:anywhere}

/* A dedicated study companion, beside lessons on desktop and above them on mobile. */
.with-study-music main{max-width:1480px;display:grid;grid-template-columns:minmax(0,1fr) 320px;gap:28px;align-items:start}
#page-content{min-width:0}.study-music{position:sticky;top:20px;padding:20px;margin:0;background:#fcfaff;max-height:calc(100vh - 40px);overflow:auto}
.study-music h2{font-size:21px;margin:4px 0 10px}.study-music p{font-size:13px;line-height:1.6}.study-music .eyebrow{font-size:10px;margin:0}.study-music label{font-size:14px}.study-music button{font-size:13px;padding:9px 12px}.music-heading{display:flex;gap:12px;align-items:start}.music-heading button{margin:0;white-space:nowrap;font-size:11px;padding:6px 8px}
.music-player{position:relative;aspect-ratio:16/9;background:#20152f;border-radius:10px;overflow:hidden;margin-top:14px}.music-player iframe{display:block;width:100%;height:100%;border:0;min-height:200px}.music-player{min-height:200px}
.music-actions{display:flex;gap:8px;flex-wrap:wrap;align-items:center}.music-actions a{font-size:13px}.music-status{overflow-wrap:anywhere}.music-help{border-top:1px solid var(--line);padding-top:12px}
.completion-list{padding:0;list-style:none}.completion-list li{padding:9px 0;border-bottom:1px solid var(--line)}.completion-list span{font-weight:800;color:var(--purple)}.exercise-feedback p{margin:8px 0}.exercise-feedback{overflow-wrap:anywhere}
section[id],form[id]{scroll-margin-top:24px}
@media(max-width:1050px){.with-study-music main{display:flex;flex-direction:column}.with-study-music #page-content{width:100%;order:2}.study-music{position:static;order:1;width:100%;max-height:none}.music-player{max-width:480px}.music-player iframe{min-height:200px}}

.notice.answer-correct,.tag.answer-correct{background:#f0fdf4;color:#166534;border-color:#15803d}.notice.answer-incorrect,.tag.answer-incorrect{background:#fef2f2;color:#991b1b;border-color:#dc2626}

.conversation{border-top:2px solid var(--line);margin-top:28px;padding-top:20px}.conversation-turn{border:1px solid var(--line);border-radius:12px;margin:18px 0;padding:18px}.conversation-turn h4{margin:0}.conversation-controls{margin-top:18px}.conversation audio{max-width:100%}

.teaching-topics{margin:22px 0;border:1px solid var(--line);border-radius:12px;padding:14px 18px}.teaching-topic{border-top:1px solid var(--line);padding:12px 0}.teaching-detail{margin:10px 0}.audio-caption{font-size:14px;font-weight:500;margin-bottom:0}