:root{color-scheme:light;--ink:#202c27;--muted:#66736b;--line:#e1e6df;--green:#245d48;--soft:#edf4ee;--paper:#fff;--bg:#f8f9f6;font-family:system-ui,-apple-system,"Segoe UI",sans-serif;font-size:15px;line-height:1.6;color:var(--ink);background:var(--bg)}
*{box-sizing:border-box}body{margin:0}button,input{font:inherit}button,a,input{touch-action:manipulation}button{cursor:pointer}a{color:var(--green);text-underline-offset:3px}button:disabled{opacity:.5;cursor:wait}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid #7cb99c;outline-offset:3px}button{border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:7px;padding:9px 15px}button:hover{background:#f0f3ee}button.primary{background:var(--green);border-color:var(--green);color:white}button.primary:hover{background:#194b39}button.text{background:none;border-color:transparent;color:var(--muted)}button.small{padding:5px 10px;font-size:13px}h1,h2,h3,p{margin-top:0}h1{font-size:30px;line-height:1.35;letter-spacing:-.7px;font-weight:650}h2{font-size:21px;line-height:1.4;font-weight:620}h3{font-size:16px}small,.muted{color:var(--muted)}.eyebrow{font-size:12px;letter-spacing:1.6px;text-transform:uppercase;color:var(--muted);margin-bottom:12px}.brand{display:inline-flex;gap:10px;align-items:center;color:var(--ink);text-decoration:none;font-size:18px;font-weight:650}.brand img{width:30px;height:30px}.topbar{height:72px;padding:0 36px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;background:var(--paper);gap:16px}.account{display:flex;align-items:center;gap:18px}.account>span{font-size:13px;color:var(--muted);max-width:220px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.loading{padding:100px 25px;text-align:center;color:var(--muted)}.auth-shell{max-width:410px;margin:70px auto;padding:0 22px}.auth-shell .brand{margin-bottom:38px}.auth-shell h1{font-size:27px;margin-bottom:10px}.auth-shell>p{color:var(--muted);margin-bottom:28px}.tabs{display:flex;border-bottom:1px solid var(--line);gap:26px;margin-bottom:26px}.tabs button{border:0;background:none;padding:10px 0;border-radius:0;color:var(--muted)}.tabs button[aria-selected=true]{color:var(--green);border-bottom:2px solid var(--green)}label.field{display:block;font-size:13px;font-weight:550;margin-bottom:18px}.field input{display:block;width:100%;margin-top:7px;padding:11px 12px;border:1px solid #cfd8cf;border-radius:6px;background:white;color:var(--ink)}.auth-shell .primary{width:100%;margin-top:4px}.hint{font-size:12px;display:block;font-weight:400;color:var(--muted);margin-top:5px}.error{color:#9a302d;font-size:14px;min-height:20px}.home{max-width:1060px;margin:64px auto;padding:0 32px}.home-intro{margin-bottom:36px}.home-intro h1{margin-bottom:10px}.home-intro p{color:var(--muted)}.section-label{font-size:14px;margin-bottom:16px;font-weight:550}.course-card{display:grid;grid-template-columns:1fr auto;gap:30px;padding:32px;border:1px solid var(--line);background:var(--paper);border-radius:12px;margin-bottom:20px;max-width:940px}.course-card h2{max-width:580px;margin-bottom:12px;font-size:25px;letter-spacing:-.4px}.course-card p{max-width:580px;color:var(--muted);font-size:14px}.course-card .course-action{align-self:end}.tag{font-size:12px;color:var(--green);display:inline-block;background:var(--soft);padding:4px 8px;border-radius:4px;margin-bottom:18px}.stats{display:flex;flex-wrap:wrap;gap:17px;font-size:13px;color:var(--muted);margin:18px 0 25px}.progress-label{font-size:12px;color:var(--muted);display:flex;justify-content:space-between;gap:20px}.progress-label strong{color:var(--green);font-weight:600}progress{appearance:none;display:block;width:100%;height:5px;border:none;border-radius:5px;overflow:hidden;background:var(--line);margin:8px 0}progress::-webkit-progress-bar{background:var(--line)}progress::-webkit-progress-value{background:var(--green);border-radius:5px}progress::-moz-progress-bar{background:var(--green)}.home-foot{font-size:12px;color:var(--muted);margin-top:26px}.study-layout{display:grid;grid-template-columns:302px minmax(0,1fr);min-height:calc(100dvh - 72px)}.sidebar{border-right:1px solid var(--line);background:#fcfdfa;height:calc(100dvh - 72px);position:sticky;top:0;overflow:auto}.side-heading{padding:25px 23px 21px;border-bottom:1px solid var(--line)}.side-heading h2{font-size:14px;line-height:1.55;margin:12px 0 17px}.back{font-size:12px;text-decoration:none;color:var(--muted)}.side-search{padding:15px 15px 5px}.side-search input{width:100%;background:white;border:1px solid var(--line);border-radius:6px;padding:9px 11px;font-size:12px}.chapter{border-bottom:1px solid var(--line)}.chapter summary{cursor:pointer;list-style:none;padding:16px 20px;display:flex;gap:12px;align-items:start;font-size:12px;font-weight:600}.chapter summary::-webkit-details-marker{display:none}.chapter summary:after{content:'+';color:var(--muted);margin-left:auto}.chapter[open] summary:after{content:'−'}.chapter-number{font-size:11px;color:var(--muted);font-variant-numeric:tabular-nums;min-width:17px}.chapter-title{line-height:1.6}.lesson-link{display:flex;padding:11px 19px 11px 24px;gap:11px;align-items:start;text-decoration:none;color:#526057;font-size:12px;line-height:1.65;border-left:3px solid transparent}.lesson-link:hover{background:#f0f4ee}.lesson-link.active{background:var(--soft);border-left-color:var(--green);color:var(--green);font-weight:600}.lesson-icon{min-width:16px;font-size:12px;color:#829087}.lesson-icon.done{color:var(--green)}.lesson-link .duration{font-size:10px;display:block;color:var(--muted);font-weight:400}.study-main{padding:32px 44px 45px;max-width:1260px;width:100%;margin:0 auto;min-width:0}.lesson-toolbar{display:flex;align-items:center;justify-content:space-between;gap:15px;margin-bottom:22px}.breadcrumb{font-size:12px;color:var(--muted);line-height:1.5}.lesson-toolbar button{white-space:nowrap}.study-main h1{font-size:25px;margin-bottom:10px;letter-spacing:-.4px}.lesson-meta{font-size:12px;color:var(--muted);display:flex;gap:14px;margin-bottom:24px}.player-wrap{width:100%;aspect-ratio:16/9;background:#14241c;border-radius:8px;overflow:hidden;display:flex;align-items:center;justify-content:center}.player-wrap iframe,.player-wrap video{width:100%;height:100%;border:0;display:block}.video-missing{color:#d4e2d6;text-align:center;padding:32px;font-size:14px}.video-missing p{margin-bottom:8px}.video-tools{display:flex;align-items:center;justify-content:space-between;gap:15px;padding:14px 0;margin-bottom:18px}.caption-select{display:flex;align-items:center;gap:8px;font-size:12px;color:var(--muted);flex-wrap:wrap}.caption-select button[aria-pressed=true]{border-color:#97b9a2;background:var(--soft);color:var(--green)}.video-tools a{font-size:12px}.info{font-size:12px;color:var(--muted);padding:12px 15px;background:#f0f3ed;border-radius:6px;margin:10px 0 24px}.lesson-footer{display:flex;justify-content:space-between;align-items:center;gap:16px;border-top:1px solid var(--line);padding-top:22px;margin-top:30px}.complete-label{display:flex;gap:8px;align-items:center;font-size:13px}.complete-label input{accent-color:var(--green);height:17px;width:17px}.navigation{display:flex;gap:8px}.article{font-size:16px;line-height:1.85;max-width:800px;padding:10px 0}.article p,.rich p{margin-bottom:16px}.article img,.rich img{max-width:100%;height:auto}.article h1,.article h2,.article h3,.article h4{margin-top:28px}.article pre,.rich pre{overflow:auto;background:#eff2ec;padding:16px;border-radius:6px;font-size:13px}.article code,.rich code{background:#eff2ec;padding:1px 4px;border-radius:3px}.article table,.rich table{max-width:100%;border-collapse:collapse}.article td,.article th,.rich td,.rich th{border:1px solid var(--line);padding:8px}.quiz-top{display:flex;align-items:center;justify-content:space-between;gap:15px;background:var(--paper);padding:16px 20px;border:1px solid var(--line);border-radius:8px;margin-bottom:24px;font-size:13px}.quiz-top strong{color:var(--green)}.question{padding:25px;background:var(--paper);border:1px solid var(--line);border-radius:9px}.question .eyebrow{margin-bottom:15px;letter-spacing:.6px}.rich{line-height:1.8;font-size:14px;overflow-wrap:anywhere}.option{display:flex;align-items:start;gap:12px;border:1px solid var(--line);border-radius:7px;padding:13px 15px;margin:11px 0;font-size:14px;cursor:pointer}.option:hover{background:#f7f9f4}.option input{margin-top:5px;accent-color:var(--green);flex-shrink:0}.option .rich p:last-child{margin:0}.option.correct{border-color:#7ea68c;background:#eff7ef}.option.wrong{border-color:#cb9c97;background:#fbf1ee}.question-actions{display:flex;justify-content:space-between;align-items:center;gap:15px;flex-wrap:wrap;margin-top:20px}.feedback{margin-top:22px;border-top:1px solid var(--line);padding-top:20px}.feedback h3{color:var(--green);font-size:14px}.feedback .wrong-title{color:#9a302d}.feedback details{font-size:13px;margin:15px 0}.feedback summary{cursor:pointer}.question-pager{display:flex;gap:6px;flex-wrap:wrap;margin-top:20px}.question-pager button{padding:4px 9px;font-size:11px;min-width:30px}.question-pager button.answered{background:var(--soft);color:var(--green)}.question-pager button[aria-current=true]{border-color:var(--green);font-weight:bold}.transcript{border-top:1px solid var(--line);margin-top:14px;padding-top:15px}.transcript>summary{cursor:pointer;font-size:13px;color:var(--muted)}.transcript-list{max-height:340px;overflow:auto;margin-top:12px}.transcript-list button{display:flex;width:100%;text-align:left;gap:15px;font-size:13px;border:0;border-bottom:1px solid #edf0ea;border-radius:0;background:none;padding:8px}.transcript-list time{color:var(--green);min-width:45px;font-size:11px;font-variant-numeric:tabular-nums}.focus .sidebar{display:none}.focus .study-layout{grid-template-columns:minmax(0,1fr)}.focus .study-main{max-width:1120px}.mobile-menu{display:none}#notice{position:fixed;bottom:20px;left:50%;transform:translateX(-50%);background:#243e30;color:white;font-size:13px;padding:12px 20px;border-radius:7px;box-shadow:0 4px 20px #0002;z-index:20;max-width:calc(100% - 30px)}[hidden]{display:none!important}.empty{font-size:13px;color:var(--muted);padding:25px}.screen-reader{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%)}
@media(min-width:1600px){.study-main{padding-top:44px}}@media(max-width:1100px){.study-layout{grid-template-columns:265px minmax(0,1fr)}.study-main{padding:28px}.sidebar{font-size:12px}.topbar{padding:0 24px}.study-main h1{font-size:23px}}@media(max-width:760px){.topbar{height:62px;padding:0 18px}.account{gap:5px}.account>span{max-width:120px;font-size:11px}.brand{font-size:16px}.brand img{width:26px;height:26px}.auth-shell{margin-top:45px}.home{margin-top:36px;padding:0 20px}.home h1{font-size:27px}.course-card{grid-template-columns:1fr;padding:23px;gap:10px}.course-card h2{font-size:22px}.course-card .primary{width:100%}.course-card .course-action{display:block}.study-layout{display:block;min-height:calc(100dvh - 62px)}.sidebar{display:none;position:fixed;left:0;top:62px;width:min(340px,90vw);height:calc(100dvh - 62px);z-index:10;box-shadow:12px 0 20px #0001}.menu-open .sidebar{display:block}.study-main{padding:22px 18px 32px}.study-main h1{font-size:22px}.mobile-menu{display:inline-block}.lesson-toolbar{margin-bottom:18px}.breadcrumb{max-width:60%;font-size:11px}.focus-toggle{display:none}.video-tools{align-items:start;flex-wrap:wrap}.lesson-footer{flex-wrap:wrap}.navigation{width:100%;justify-content:space-between}.question{padding:18px}.quiz-top{padding:13px 15px;font-size:12px}.article{font-size:15px}.option{padding:11px}.question-actions{align-items:start}.stats{gap:12px}.focus .sidebar{display:none}}
@media(prefers-reduced-motion:no-preference){button,a{transition:background .12s,color .12s}}