:root{--ink:#18221e;--muted:#4b5852;--paper:#f4f6f4;--sheet:#fcfdfb;--line:#c9d0cc;--line-strong:#89968f;--green:#255f4b;--green-dark:#174536;--green-soft:#edf4f0;--error:#8b2f2f;--focus:#155f8f}.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}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--paper);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;line-height:1.58;font-synthesis:none}.app-shell{display:grid;grid-template-columns:230px minmax(0,1fr);min-height:100vh}.course-nav{position:sticky;top:0;height:100vh;padding:24px 18px;background:var(--sheet);border-right:1px solid var(--line);overflow:auto}.nav-title{padding:0 4px 18px;border-bottom:2px solid var(--ink)}.nav-title span,.nav-title small{display:block;color:var(--muted);font-size:10px}.nav-title span{color:var(--green);letter-spacing:.08em;text-transform:uppercase}.nav-title strong{display:block;margin:4px 0;font-size:19px}.course-nav nav{margin-top:10px}.course-nav a{display:block;padding:9px 4px;color:var(--muted);border-bottom:1px solid var(--line);font-size:12px;text-decoration:none}.course-nav a:hover,.course-nav a.active{color:var(--green-dark);font-weight:700;box-shadow:inset 0 -2px var(--green)}.course-nav a small{display:block;font-size:10px;font-weight:400}.notebook-open{position:sticky;bottom:0;width:100%;min-height:42px;margin-top:18px;border:1px solid var(--green-dark);background:var(--sheet);color:var(--green-dark);font:700 12px inherit;cursor:pointer}.notebook-open span{display:inline-grid;min-width:21px;height:21px;margin-left:5px;padding:0 5px;place-items:center;background:var(--green);color:#fff;border-radius:50%}
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.selection-popover{position:fixed;z-index:30;width:min(340px,calc(100vw - 24px));padding:14px;background:var(--sheet);border:1px solid var(--line-strong);box-shadow:0 5px 12px rgba(24,34,30,.14)}.popover-head{display:flex;justify-content:space-between;align-items:center}.popover-head strong{font-size:12px}.popover-head button,.notebook header button{width:32px;height:32px;border:0;background:transparent;color:var(--muted);font-size:22px;cursor:pointer}.selected-source{margin:10px 0 4px;color:var(--muted);font-size:11px}.selected-translation{margin:0 0 12px;font-size:14px;font-weight:650}.selection-popover label{display:block;margin-bottom:4px;color:var(--muted);font-size:11px}.selection-popover textarea{width:100%;padding:8px;border:1px solid var(--line-strong);border-radius:0;background:var(--sheet);color:var(--ink);font:12px inherit;resize:vertical}.selection-popover>button{width:100%;margin-top:9px}.notebook-backdrop{position:fixed;inset:0;z-index:39;background:rgba(24,34,30,.18)}.notebook{position:fixed;z-index:40;top:0;right:0;width:min(390px,100vw);height:100vh;padding:20px;background:var(--sheet);border-left:1px solid var(--line-strong);transform:translateX(102%);transition:transform .2s ease-out;overflow:auto}.notebook.open{transform:translateX(0)}.notebook header{display:flex;justify-content:space-between;align-items:flex-start;padding-bottom:13px;border-bottom:2px solid var(--ink)}.notebook header span{color:var(--green);font-size:10px}.notebook header h2{font-size:23px}.notebook-help{color:var(--muted);font-size:11px}.notebook-empty{padding:24px 0;color:var(--muted);font-size:12px}.note-item{padding:15px 0;border-bottom:1px solid var(--line)}.note-meta{display:flex;justify-content:space-between;gap:10px;color:var(--muted);font-size:9px}.note-source{margin:8px 0 3px;font-size:12px}.note-translation{margin:0;color:var(--green-dark);font-size:13px;font-weight:650}.note-personal{margin:8px 0 0;padding-top:7px;border-top:1px dashed var(--line);font-size:11px}.note-remove{margin-top:8px;padding:0;border:0;background:transparent;color:var(--error);font:600 10px inherit;cursor:pointer}
@media(max-width:780px){.app-shell{display:block}.course-nav{position:relative;height:auto;padding:16px 18px;border-right:0;border-bottom:1px solid var(--line)}.course-nav nav{display:grid;grid-template-columns:1fr 1fr;max-height:210px;overflow:auto}.notebook-open{position:static}main{padding:24px 20px 60px}.course-header,.section-heading,.unit-header,.aims,.unit-body{grid-template-columns:1fr}.course-header{gap:15px}.course-header dl{border-top:1px solid var(--line);padding-top:12px}.section-heading,.unit-header,.aims{gap:6px}.unit-body{gap:24px}.unit-body>div+div{padding:22px 0 0;border-left:0;border-top:1px solid var(--line)}.exam-tip{grid-template-columns:28px 1fr}.page-ref{grid-column:2}.notebook{width:100vw}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.notebook{transition:none}}