:root{color-scheme:light;--ink:#17252c;--muted:#64727a;--line:#e2e7e8;--accent:#17634e;--pale:#edf5ef;--bg:#f5f7f7}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.6 -apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans SC",sans-serif}a{color:var(--accent)}button,select{font:inherit}button,a,summary,select{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:focus-visible,a:focus-visible,summary:focus-visible,select:focus-visible{outline:3px solid #278c71;outline-offset:4px}button:disabled{cursor:default;opacity:.45}.skip{position:fixed;top:-100px;left:20px;background:white;padding:10px;z-index:20}.skip:focus{top:10px}.topbar{height:88px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 4vw;gap:20px}.brand{display:flex;align-items:center;gap:12px;color:var(--ink);text-decoration:none;font-size:20px;font-weight:650;letter-spacing:.04em}.brand small{display:block;font-size:10px;font-weight:600;letter-spacing:.18em;color:var(--muted);line-height:1.2;margin-top:3px}.brand-icon{background:#193e35;color:#fff;width:42px;height:44px;border-radius:10px;display:grid;place-items:center;font-size:27px}.header-label{font-size:14px;color:var(--muted)}.divider{padding:0 16px;color:#b6c2c3}.workspace{display:grid;grid-template-columns:294px minmax(0,1fr);max-width:1472px;margin:0 auto;min-height:calc(100vh - 88px)}.sidebar{border-right:1px solid var(--line);padding:35px 22px 32px 18px}.course-heading{padding:0 14px 27px}.eyebrow{font-size:11px;letter-spacing:.16em;font-weight:700;color:#75847e}.course-heading h1{font-size:24px;letter-spacing:-.04em;line-height:1.3;margin:13px 0 7px}.course-heading p{font-size:14px;color:var(--muted);margin:0}.counts{display:flex;gap:8px;margin-top:19px;font-size:12px;color:#5a6863}.counts span{border:1px solid #dbe3df;border-radius:5px;padding:2px 9px}.directory summary{list-style:none;font-size:14px;font-weight:650;display:flex;justify-content:space-between;padding:12px 14px;cursor:pointer}.directory summary::-webkit-details-marker{display:none}.section-label{font-size:12px;color:var(--muted);padding:18px 14px 9px;letter-spacing:.04em}.lesson-link{position:relative;display:flex;align-items:flex-start;gap:11px;border-radius:8px;text-decoration:none;color:#4b575c;padding:15px 12px;margin:3px 0}.lesson-link:hover{background:#eaf0ee}.lesson-link[aria-current=page]{background:#e1eee6;color:#164c37}.lesson-link[aria-current=page]:before{content:"";position:absolute;left:0;top:16px;bottom:16px;width:3px;background:#22664c;border-radius:3px}.lesson-index{font-size:12px;padding-top:3px;color:#6c7b73;min-width:19px;font-variant-numeric:tabular-nums}.lesson-link strong{display:block;font-size:14px;font-weight:550;line-height:1.55}.lesson-link small{display:block;font-size:12px;color:#78847f;margin-top:5px}.sidebar-note{margin:36px 14px 0;border-top:1px solid var(--line);padding-top:20px;font-size:12px;color:#88928e;line-height:1.9}main{padding:34px 48px 60px;min-width:0}.breadcrumb{font-size:13px;color:#85908c;margin-bottom:20px}.title-row h2{font-size:29px;font-weight:650;line-height:1.4;letter-spacing:-.04em;margin:0 0 7px}.subtitle{font-size:14px;color:var(--muted);margin:0}.lesson-meta{display:flex;gap:13px;align-items:center;font-size:12px;color:var(--muted);margin:15px 0 24px}.badge{background:#e8efeb;border:1px solid #dce6df;padding:2px 9px;border-radius:5px;color:#365b49}.player{position:relative;background:#101b19;border-radius:12px;overflow:hidden;aspect-ratio:16/9;box-shadow:0 4px 18px #1b31270b}.player video{width:100%;height:100%;display:block;object-fit:contain}.play-start{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;flex-direction:column;gap:14px;background:linear-gradient(transparent,#0004);border:0;color:#fff;text-shadow:0 1px 5px #000}.play-circle{display:grid;place-items:center;width:68px;height:68px;border-radius:50%;background:#fff;color:#173e32;font-size:25px;padding-left:4px;box-shadow:0 2px 15px #0003}.play-start:hover .play-circle{transform:scale(1.06)}.play-caption{background:#10251ee6;border-radius:20px;padding:5px 17px;font-size:13px}.player-tools{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px 0 24px;font-size:13px;color:var(--muted)}.player-tools select{border:1px solid var(--line);border-radius:5px;padding:4px;background:#fff;font-size:13px}.player-tools label{display:flex;align-items:center;gap:8px}.error{padding:15px;border:1px solid #d8a771;background:#fff7eb;border-radius:7px;font-size:14px}.retry{margin-left:12px;background:#fff;border:1px solid #ae8354;border-radius:4px}.tabs{display:flex;border-bottom:1px solid var(--line);gap:28px}.tabs button{background:transparent;color:var(--muted);padding:13px 1px;border:0;border-bottom:2px solid transparent;font-size:14px}.tabs button[aria-selected=true]{color:#174e39;border-bottom-color:#174e39;font-weight:650}.panel{background:#fff;border:1px solid var(--line);border-radius:10px;margin-top:21px;padding:25px 29px;min-width:0}.article{font-size:16px;line-height:1.95;overflow-wrap:anywhere}.article h1{font-size:25px;line-height:1.5;margin:0 0 20px}.article h2{font-size:20px;margin:30px 0 13px}.article p{margin:0 0 18px}.article ul,.article ol{padding-left:23px}.article li{padding-left:3px;margin:8px 0}.article strong{font-weight:650}.article table{border-collapse:collapse;min-width:520px;font-size:14px;width:100%}.article td,.article th{text-align:left;padding:12px;border:1px solid var(--line)}.article th{background:#f4f7f5}.table-scroll{overflow-x:auto;margin-bottom:24px}.article h2:first-child{margin-top:0}.muted-note{font-size:13px;color:var(--muted);line-height:1.8}.transcript{max-height:530px;overflow-y:auto}.cue{display:grid;grid-template-columns:68px 1fr;gap:15px;margin-bottom:16px;align-items:start}.cue button{border:0;border-radius:5px;background:var(--pale);color:var(--accent);padding:4px;font-size:12px;font-variant-numeric:tabular-nums}.cue p{margin:0;font-size:15px}.resource{display:flex;align-items:center;justify-content:space-between;gap:18px;color:var(--ink);text-decoration:none;border-bottom:1px solid var(--line);padding:17px 0}.resource:first-of-type{padding-top:4px}.resource:last-child{border-bottom:0}.resource strong{font-size:15px;font-weight:550}.resource small{display:block;font-size:12px;color:var(--muted);margin-top:3px}.resource span:last-child{color:var(--accent);font-size:14px}.lesson-footer{display:flex;gap:20px;justify-content:space-between;border-top:1px solid var(--line);margin-top:32px;padding-top:23px}.lesson-footer a{max-width:48%;text-decoration:none;font-size:14px;color:var(--ink)}.lesson-footer a:last-child{text-align:right;margin-left:auto}.lesson-footer small{display:block;font-size:12px;color:var(--muted);margin-bottom:4px}.loading{color:var(--muted)}[hidden]{display:none!important}@media(min-width:1700px){main{padding-left:60px;padding-right:60px}}@media(max-width:1050px){.workspace{grid-template-columns:260px minmax(0,1fr)}main{padding:28px}.sidebar{padding-right:15px}.title-row h2{font-size:25px}.header-label{font-size:12px}}@media(max-width:720px){.topbar{height:72px;padding:0 20px}.header-label{display:none}.brand{font-size:18px}.workspace{display:block}.sidebar{border-right:0;border-bottom:1px solid var(--line);padding:16px 18px}.course-heading{padding:0 10px 9px}.course-heading h1{font-size:20px;margin:0}.course-heading .eyebrow,.course-heading p,.counts,.sidebar-note{display:none}.directory summary{padding:9px 10px}.directory nav{max-height:370px;overflow:auto}.section-label{padding-top:10px}main{padding:23px 18px 40px}.breadcrumb{margin-bottom:13px}.title-row h2{font-size:25px}.player{border-radius:8px}.panel{padding:20px 18px}.tabs{gap:24px}.player-tools{align-items:flex-start}.player-tools>span{max-width:57%}.lesson-footer{gap:10px}.lesson-footer a{font-size:13px}.article{font-size:16px}.cue{gap:10px;grid-template-columns:60px 1fr}}
/* 多语言与长文本：使用逻辑边距支持阿拉伯语排版。 */
.header-actions{display:flex;align-items:center;gap:24px;min-width:0}.language-control{display:flex;align-items:center;gap:8px;color:var(--muted);flex-shrink:0}.language-control select{max-width:155px;min-height:38px;border:1px solid var(--line);border-radius:7px;background:#fff;color:var(--ink);padding:5px 10px;font-size:14px}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.brand{min-width:0}.brand small{font-size:11px}.brand>span:last-child{line-height:1.35}.counts{flex-wrap:wrap}.tabs{gap:22px}.tabs button{overflow-wrap:anywhere}.lesson-meta{flex-wrap:wrap}.player-tools label{flex-shrink:0}.transcript{direction:ltr;text-align:left}.play-caption{max-width:90%;text-align:center}.resource strong,.resource small,.lesson-footer a{overflow-wrap:anywhere}.article td,.article th{text-align:start}html[dir=rtl] .sidebar{border-right:0;border-left:1px solid var(--line)}html[dir=rtl] .lesson-link[aria-current=page]:before{left:auto;right:0}html[dir=rtl] .lesson-footer a:last-child{text-align:left;margin-left:0;margin-right:auto}html[dir=rtl] .article ul,html[dir=rtl] .article ol{padding-left:0;padding-right:23px}html[dir=rtl] .subtitle,html[dir=rtl] video{direction:ltr}html[dir=rtl] .play-circle{padding-left:4px;direction:ltr}
@media(max-width:1100px){.header-actions .header-label{display:none}.brand{font-size:18px;letter-spacing:0}}@media(max-width:720px){.topbar{height:auto;min-height:76px;padding:12px 18px;gap:12px}.brand{font-size:16px;gap:8px;max-width:65%}.brand-icon{width:34px;height:38px;flex-shrink:0}.brand small{font-size:10px;letter-spacing:.06em}.language-control{gap:4px}.language-control>span[aria-hidden]{display:none}.language-control select{max-width:120px;font-size:13px;padding:5px}.header-actions{gap:0}.tabs{gap:16px}.tabs button{font-size:13px}.player-tools{flex-wrap:wrap}.player-tools>span{max-width:100%}html[dir=rtl] .sidebar{border-left:0}}
.youtube-player{min-height:210px;background:#152820}.youtube-player iframe{width:100%;height:100%;border:0;display:block}.youtube-player+.muted-note{margin:14px 0 5px}#youtube-fallback{font-size:13px}#foundation-notes h2{margin-top:0}

.article-summary{direction:inherit!important}.lesson-meta time{direction:ltr;unicode-bidi:isolate}@media(min-width:721px){.sidebar{position:sticky;top:0;align-self:start;max-height:100vh;overflow-y:auto}}

/* The account itself stays on the canonical store origin, including its session. */
.account-entry{color:var(--ink,#193e37);font-weight:650;text-decoration:none;border:1px solid #d5ded9;border-radius:8px;padding:9px 14px;white-space:nowrap}
.account-entry:hover,.account-actions a:hover,.account-shortcuts a:hover{background:#edf3ef}
.account-actions,.account-shortcuts{display:flex;flex-wrap:wrap;align-items:center;gap:10px;margin:16px 0}
.account-actions a,.account-actions button,.account-shortcuts a{font:inherit;font-size:14px;color:#214b3e;border:1px solid #d5ded9;border-radius:8px;background:white;padding:9px 14px;text-decoration:none;cursor:pointer}
.account-frame{display:block;width:100%;height:78vh;min-height:640px;border:1px solid #d5ded9;border-radius:12px;background:white}
@media(max-width:720px){.account-frame{min-height:600px;height:80vh}.account-entry{font-size:13px;padding:8px}.header-actions{flex-wrap:wrap;justify-content:flex-end}}