*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0!important;padding:0!important;background:#fff;color:var(--lr-ink-900);font-family:var(--lr-font-body);font-size:18px;line-height:1.55}
button,input{font:inherit}
.lesson{width:min(100% - 32px,1184px);margin:0 auto;padding:34px 0 72px}
.eyebrow{margin:0 0 10px;color:var(--lr-coral-600);font-size:13px;font-weight:800;letter-spacing:.08em;text-transform:uppercase}
.hero{max-width:930px;margin-bottom:28px}
.hero h1{margin:0 0 18px;font-size:clamp(38px,6vw,66px);line-height:1.02}
.hero .thesis{max-width:850px;margin:0;color:var(--lr-slate-700);font-size:clamp(18px,2vw,22px)}
.notice{margin-top:18px;padding:14px;border-left:4px solid var(--lr-blue-500);background:var(--lr-slate-100);color:var(--lr-slate-700);font-size:14px}
.section{margin-top:30px}
.panel{overflow:hidden;border:1px solid var(--lr-slate-200);border-radius:8px;background:#fff}
.tabs{display:flex;gap:0;overflow-x:auto;border-bottom:1px solid var(--lr-slate-200);background:var(--lr-slate-100)}
.tabs button{flex:0 0 auto;min-height:48px;padding:0 18px;border:0;border-right:1px solid var(--lr-slate-200);background:transparent;color:var(--lr-slate-700);font-weight:800;cursor:pointer}
.tabs button.active{background:#fff;color:var(--lr-coral-600);box-shadow:inset 0 -3px var(--lr-coral-500)}
.tabs button:focus-visible,.download:focus-visible,.answer button:focus-visible,.summary-jump:focus-visible{outline:3px solid var(--lr-blue-500);outline-offset:2px}
.tab-panel{padding:20px}
.hidden{display:none!important}
.chapter-list{display:grid;gap:10px}
.chapter{display:grid;grid-template-columns:86px 1fr;gap:16px;width:100%;padding:15px;border:1px solid var(--lr-slate-200);border-radius:6px;background:#fff;color:var(--lr-ink-900);text-align:left}
.chapter time,.summary-time,.practice-time{color:var(--lr-coral-600);font-family:var(--lr-font-mono);font-size:12px;font-weight:700}
.chapter strong{display:block;font-family:var(--lr-font-display);font-size:20px;line-height:1.2}
.chapter p{margin:6px 0 0;color:var(--lr-slate-700);font-size:15px}
.mindmap-figure{margin:0}
.mindmap-stage{overflow:hidden;border:1px solid var(--lr-slate-200);border-radius:8px;background:#fff}
.mindmap-stage>img{display:block;width:100%;height:auto}
.mindmap-actions{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:12px;padding:16px 2px 0}
.mindmap-actions p{margin:0;color:var(--lr-slate-700)}
.download{display:inline-flex;align-items:center;justify-content:space-between;gap:12px;min-height:44px;padding:9px 14px;border:1px solid var(--lr-coral-500);border-radius:4px;background:var(--lr-coral-500);color:#fff;font-weight:800;text-decoration:none}
.download:hover{background:var(--lr-coral-700)}
.summary-lead{margin:0 0 16px;color:var(--lr-slate-700);font-size:18px}
.search{width:100%;min-height:46px;padding:0 14px;border:1px solid var(--lr-slate-300);border-radius:4px}
.summary{display:grid;gap:12px;margin-top:14px}
.summary-section{padding:18px;border:1px solid var(--lr-slate-200);border-radius:6px;background:#fff}
.summary-section header{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:10px;margin-bottom:7px}
.summary-section header>div{display:flex;flex-wrap:wrap;align-items:center;gap:10px}
.summary-section time{color:var(--lr-coral-600);font-family:var(--lr-font-mono);font-size:12px;font-weight:800}
.summary-section h3{margin:0;font-family:var(--lr-font-display);font-size:22px;line-height:1.2}
.summary-section p{margin:10px 0 0;color:var(--lr-slate-700)}
.summary-time,.practice-time{display:inline-flex;align-items:center;min-height:34px;padding:6px 10px;border-radius:4px;background:var(--lr-slate-100);color:var(--lr-slate-700)}
.practice{display:grid;gap:14px}
.question{padding:18px;border:1px solid var(--lr-slate-200);border-radius:6px;background:#fff}
.question>p:first-child{margin-top:0;font-weight:700}
.answer{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px}
.answer button{min-height:44px;padding:9px 14px;border:1px solid var(--lr-coral-500);border-radius:4px;background:#fff;color:var(--lr-coral-600);font-weight:800;cursor:pointer}
.answer button:hover{background:var(--lr-coral-500);color:#fff}
.feedback{margin-top:10px;padding:10px;border-left:3px solid var(--lr-coral-500);background:var(--lr-coral-100);color:var(--lr-ink-700)}
.downloads{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.pdf-note{margin:16px 0 0;color:var(--lr-slate-500);font-size:13px}
@media(max-width:700px){.lesson{width:min(100% - 20px,1184px);padding:22px 0 48px}.section{margin-top:22px}.tab-panel{padding:14px}.chapter{grid-template-columns:1fr;gap:7px}.downloads{grid-template-columns:1fr}.summary-section header>div{gap:6px}}