:root{color-scheme:light;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;color:#1d2430;background:#f6f4ef;font-synthesis:none;text-rendering:optimizeLegibility;-webkit-font-smoothing:antialiased}*{box-sizing:border-box}body{margin:0;min-width:320px}button,input{font:inherit}a{color:inherit;text-decoration:none}.app-shell{min-height:100vh;background:linear-gradient(180deg,#ffffffb8,#fff0 360px),#f6f4ef}.topbar{align-items:center;border-bottom:1px solid #ded8cb;display:flex;gap:18px;height:56px;justify-content:space-between;margin:0 auto;max-width:560px;padding:0 14px;position:sticky;top:0;z-index:5;background:#f6f4efeb;-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px)}.brand{align-items:center;display:inline-flex;gap:10px;font-weight:760}.brand-mark{align-items:center;background:#2f5f5b;border-radius:8px;color:#fff;display:inline-flex;height:32px;justify-content:center;width:32px}.topbar-search{display:none}.home-feed,.page-grid{display:grid;gap:16px;grid-template-columns:1fr;margin:0 auto;max-width:560px;padding:16px 12px 28px}.artist-strip{display:flex;gap:8px;margin:0 -12px;overflow-x:auto;padding:0 12px 2px;scrollbar-width:none}.artist-strip::-webkit-scrollbar{display:none}.artist-strip button{align-items:center;background:#fffdfa;border:1px solid #ded7c8;border-radius:999px;color:#4d5a55;cursor:pointer;display:inline-flex;flex:0 0 auto;font-weight:760;gap:8px;min-height:40px;padding:8px 13px}.artist-strip button.active{background:#2f6f58;border-color:#2f6f58;color:#fff}.artist-strip span{align-items:center;background:#2f5f5b1a;border-radius:999px;display:inline-flex;font-size:.78rem;justify-content:center;min-width:24px;padding:3px 7px}.artist-strip button.active span{background:#ffffff2e}.study-panel{border-bottom:1px solid #ddd6c7;padding:4px 0 14px}.section-heading h1,.lesson-summary h1{font-size:clamp(1.78rem,9vw,2.7rem);line-height:1.08;margin:0}.eyebrow{color:#8a5d2c;font-size:.78rem;font-weight:780;letter-spacing:0;margin:0 0 12px;text-transform:uppercase}.metric-row{display:grid;gap:10px;grid-template-columns:repeat(2,minmax(0,1fr));margin-top:16px}.metric-row div{background:#fffdfa;border:1px solid #ded7c8;border-radius:8px;display:grid;gap:2px;padding:12px}.metric-row strong{font-size:1.35rem}.metric-row span{color:#687069}.lesson-list{display:grid;gap:10px}.lesson-card{align-items:stretch;background:#fffdfa;border:1px solid #ded7c8;border-radius:8px;display:grid;gap:0;grid-template-columns:1fr;min-height:0;overflow:hidden;padding:0;transition:border-color .16s ease,transform .16s ease,box-shadow .16s ease}.lesson-card:hover{border-color:#91aaa4}.lesson-card:active{transform:scale(.995)}.lesson-thumbnail{aspect-ratio:16 / 9;background:#1f2426;overflow:hidden;position:relative}.lesson-thumbnail img{display:block;height:100%;object-fit:cover;width:100%}.thumbnail-empty{height:100%;width:100%}.play-badge{align-items:center;background:#1d2430c7;border-radius:999px;color:#fff;display:inline-flex;height:42px;justify-content:center;left:50%;position:absolute;top:50%;transform:translate(-50%,-50%);width:42px}.lesson-card-main{padding:14px}.lesson-meta-line{color:#657067;display:flex;flex-wrap:wrap;display:grid;font-size:.84rem;gap:3px}.lesson-meta-line span+span:before{color:#b1aa9d;content:"";margin-right:0}.lesson-card h2{font-size:clamp(1.35rem,7vw,1.85rem);line-height:1.25;margin:8px 0 12px;word-break:keep-all}.target-row,.summary-tags,.chunk-row{display:flex;flex-wrap:wrap;gap:8px}.target-row span,.summary-tags span{align-items:center;background:#edf3ef;border:1px solid #d8e5df;border-radius:999px;color:#315652;display:inline-flex;gap:6px;font-size:.82rem;min-height:32px;padding:6px 10px}.skeleton{animation:pulse 1.2s ease-in-out infinite;background:linear-gradient(90deg,#f3eee4,#fffdfa,#f3eee4)}@keyframes pulse{0%,to{opacity:.65}50%{opacity:1}}.state-message{background:#fffdfa;border:1px solid #ded7c8;border-radius:8px;padding:22px}.state-message h2{margin:0 0 6px}.state-message p{color:#687069;margin:0}.detail-wrap,.lesson-session{margin:0 auto;max-width:560px;padding:14px 12px 28px}.back-link{align-items:center;color:#4c6762;display:inline-flex;font-weight:720;gap:8px;margin-bottom:12px;min-height:40px}.lesson-session{min-height:calc(100vh - 56px);display:grid;grid-template-rows:auto auto auto minmax(0,1fr) 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button:hover,.icon-button:hover{border-color:#91aaa4}.choice-list button.correct,.choice-list button.wrong{color:#fff}.choice-list button.correct{background:#2f6f58;border-color:#2f6f58}.choice-list button.wrong{background:#a44945;border-color:#a44945}.feedback{align-items:center;border-radius:8px;display:flex;gap:8px;margin-top:12px;padding:10px 12px}.feedback.correct{background:#edf7f0;color:#245c3f}.feedback.wrong{background:#faeeee;color:#8c312e}.practice-header{display:grid;gap:10px;margin-bottom:8px}.practice-header h3{color:#58645f;font-size:1rem;font-weight:650;line-height:1.45;margin:0}.practice-context{color:#1d2430;font-size:clamp(1.85rem,9vw,3rem);font-weight:760;line-height:1.16;margin:6px 0 14px;word-break:keep-all}.ordering-answer,.speaking-box{align-items:center;background:#f8f5ee;border:1px solid #e3dccf;border-radius:8px;display:flex;gap:10px;margin-bottom:12px;min-height:52px;padding:11px 12px}.speaking-box span,.ordering-answer{font-size:1.18rem}.icon-button{align-items:center;display:inline-flex;justify-content:center;text-align:center;width:42px}@media(min-width:640px){.app-shell{background:linear-gradient(90deg,#ded8cb8c 0,#ded8cb00 18%,#ded8cb00 82%,#ded8cb8c),#f6f4ef}.topbar,.home-feed,.page-grid,.detail-wrap,.lesson-session{border-left:1px solid #ded8cb;border-right:1px solid #ded8cb}}