:root{--ink:#25475d;--muted:#637b8b;--teal:#147c86;--line:#d9e6ee;--soft:#f2f7fa;--gold:#ae7b32}*{box-sizing:border-box}body{margin:0;background:#f3f7fa;color:var(--ink);font:15px/1.7 system-ui,-apple-system,"Microsoft YaHei",sans-serif}a{color:#236c92;text-decoration:none}a:hover{text-decoration:underline}button,input,select,textarea{font:inherit}button,select{cursor:pointer}button,.link-button{padding:9px 15px;border:1px solid #c7dbe5;background:#fff;border-radius:10px;color:var(--ink)}button:hover{background:#edf7f8}button:disabled{opacity:.5;cursor:wait}button.primary{background:var(--teal);color:#fff;border-color:var(--teal)}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible,canvas:focus-visible{outline:3px solid #6db2ce;outline-offset:3px}[hidden]{display:none!important}.topbar{min-height:84px;background:#ffffffec;display:flex;justify-content:space-between;align-items:center;padding:15px 4vw;border-bottom:1px solid var(--line);gap:25px}.brand{display:flex;align-items:center;gap:10px;color:var(--ink);font-size:21px;font-weight:750}.brand:hover{text-decoration:none}.brand small{display:block;font-size:11px;letter-spacing:1px;font-weight:450}.brand-mark{display:grid;place-items:center;width:44px;height:44px;border-radius:14px;background:#1a8790;color:#fff;font-size:24px}.topbar nav{display:flex;gap:24px;font-size:14px}main{max-width:1550px;margin:auto;padding:40px 4vw 70px}.intro{display:flex;justify-content:space-between;gap:50px;align-items:center;margin-bottom:28px}.intro h1{font-size:clamp(31px,3.5vw,47px);line-height:1.3;letter-spacing:1px;margin:10px 0 18px}.intro p{max-width:760px;color:var(--muted);margin:8px 0}.eyebrow{font-size:10px;letter-spacing:2.3px;font-weight:750;color:#56818f}.identity-card{min-width:280px;background:#fff;border:1px solid var(--line);padding:22px 25px;border-radius:20px}.identity-card b{font-size:17px}.identity-card a{font-size:13px}.small{font-size:12px;color:var(--muted)}.notice{padding:15px 20px;background:#fff8e9;border:1px solid #efdfbd;border-radius:12px;margin:18px 0}.layout{display:grid;grid-template-columns:235px minmax(0,1fr);gap:22px;align-items:start}.course-nav{position:sticky;top:18px;background:#fff;border:1px solid var(--line);border-radius:18px;padding:18px 13px}.panel-heading{display:flex;justify-content:space-between;padding:0 8px;align-items:center}.panel-heading h2{font-size:18px;margin:0}.panel-heading span{font-size:12px;color:#8095a3}.nav-group{margin-top:22px}.nav-group h3{font-size:11px;color:#64808e;font-weight:500;margin:0 9px 8px;letter-spacing:.5px}.course-link{width:100%;display:flex;text-align:left;gap:10px;border:0;border-radius:9px;padding:10px;background:#fff;line-height:1.5;font-size:13px;margin:2px 0}.course-link.active{background:#e5f3f3;color:#146c76;font-weight:700}.course-link .nav-number{font-size:10px;min-width:20px;color:#8395a0;padding-top:3px}.material-link{display:block;border-top:1px solid var(--line);padding:16px 8px 0;margin-top:18px;font-size:12px}.workspace{min-width:0;display:grid;gap:20px}.panel{background:#fff;border:1px solid var(--line);border-radius:19px;padding:26px}.panel h2{font-size:24px;margin:7px 0 12px}.pill{display:inline-block;color:#39707b;background:#eaf4f5;font-size:11px;padding:4px 10px;border-radius:30px}.course-panel>p{color:var(--muted)}.task-list{display:grid;gap:12px;grid-template-columns:repeat(3,minmax(0,1fr));margin:20px 0}.task{border:1px solid #e0e9ef;border-radius:12px;padding:15px;background:#f9fbfc}.task h3{font-size:14px;margin:0 0 8px}.task p{font-size:13px;margin:5px 0 10px}.task small{font-size:11px;color:var(--muted);line-height:1.65;display:block}.link-button{display:inline-block;font-size:13px;background:#edf7f8}.section-title{display:flex;align-items:center;justify-content:space-between;gap:20px}.section-title h2{margin-bottom:5px}.section-title>a{font-size:12px}.atlas-toolbar{display:flex;gap:16px;align-items:center;flex-wrap:wrap;margin:20px 0 17px;font-size:13px}.atlas-toolbar label{display:flex;align-items:center;gap:8px}.atlas-toolbar select{padding:7px;border:1px solid #d0dfe6;border-radius:7px;background:#fff;color:var(--ink);max-width:165px}.atlas-toolbar input[type=checkbox]{accent-color:var(--teal);width:16px;height:16px}.atlas-workspace{display:grid;grid-template-columns:minmax(0,1fr) 225px;gap:15px}.stage{position:relative;min-height:470px;overflow:hidden;border-radius:12px;background:#eef4f8;border:1px solid #dce7ee}.stage canvas{display:block;width:100%;height:520px;touch-action:none}.placeholder{position:absolute;inset:0 0 70px;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center;padding:25px;color:#5f7d8e;pointer-events:none}.placeholder p{font-size:13px}.placeholder b{font-weight:500}.atlas-symbol{font-size:70px;font-weight:250;color:#8fb0c1;margin-bottom:15px}.viewer-status{position:absolute;left:14px;top:12px;right:14px;pointer-events:none;font-size:11px;color:#4b738a;background:#ffffffd6;border-radius:7px;padding:7px 9px}.viewer-status b{font-weight:500}.view-buttons{position:absolute;display:flex;gap:5px;left:12px;bottom:12px;flex-wrap:wrap}.view-buttons button{padding:6px 10px;font-size:12px;background:#ffffffeb}.structure-panel{display:flex;flex-direction:column;min-width:0}.structure-panel label{font-size:12px}.structure-panel input{width:100%;padding:9px;border:1px solid #d5e3eb;border-radius:8px;margin-top:6px;font-size:12px}.structure-panel>p{margin:8px 0}.structure-panel #structureList{height:456px;overflow:auto;padding-right:3px}.structure-item{padding:9px;width:100%;display:block;text-align:left;border:1px solid transparent;border-bottom-color:#e5edf2;border-radius:6px;font-size:12px}.structure-item small{display:block;font-size:10px;color:var(--muted)}.structure-item.selected{border-color:#8ec5c7;background:#e6f4f3}.selection-details{padding:18px 4px 0;margin-top:16px;border-top:1px solid #e4edf2;font-size:13px}.selection-details>b{font-size:17px}.selection-details p{margin:7px 0}.selection-details dl{display:grid;grid-template-columns:52px minmax(0,1fr);gap:6px 12px;margin-bottom:0}.selection-details dt{color:#6a8190}.selection-details dd{margin:0}.selection-details .source{font-size:11px;color:var(--muted);overflow-wrap:anywhere}.mechanism-panel>p{font-size:13px;color:var(--muted)}.mechanism-inner{display:grid;grid-template-columns:1.3fr 1fr;gap:28px;align-items:center}.mechanism-inner svg{width:100%;border:1px solid var(--line);border-radius:10px;background:#f7fafc}.mechanism-inner label{font-size:15px;font-weight:700}.mechanism-inner output{margin-left:15px;color:var(--teal)}input[type=range]{width:100%;margin:18px 0;accent-color:var(--teal)}.record-panel>label{display:block;margin:14px 0 7px;font-size:13px}.record-panel textarea{width:100%;padding:13px;border:1px solid #d1e0e8;border-radius:10px;resize:vertical;color:var(--ink);background:#fcfdfe;line-height:1.7;font-size:13px}.record-actions{display:flex;gap:12px;align-items:center;flex-wrap:wrap;margin:18px 0 12px}.record-actions a{font-size:12px}.recent-row{padding:12px 0;border-top:1px solid #e4edf2;font-size:12px}.recent-row p{margin:4px 0;color:var(--muted);white-space:pre-wrap;overflow-wrap:anywhere}footer{max-width:1500px;margin:auto;padding:22px 4vw 40px;display:flex;justify-content:space-between;gap:20px;font-size:11px;color:#6e8797;border-top:1px solid var(--line)}@media(max-width:1150px){.layout{grid-template-columns:205px minmax(0,1fr)}.atlas-workspace{grid-template-columns:minmax(0,1fr) 180px}.task-list{grid-template-columns:1fr}.task{padding:13px 16px}.task p{margin-bottom:6px}}@media(max-width:900px){.topbar{align-items:flex-start;padding:15px 5vw}.topbar nav{gap:12px;flex-wrap:wrap;justify-content:flex-end;font-size:12px}.intro{gap:22px}.identity-card{min-width:220px;padding:18px}.layout{grid-template-columns:1fr}.course-nav{position:static}.course-nav #courseNav{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.nav-group{margin-top:15px}.panel-heading{border-bottom:1px solid var(--line);padding-bottom:10px}.course-link{padding:8px 5px;font-size:12px}.course-link .nav-number{min-width:17px}.material-link{font-size:12px}.task-list{grid-template-columns:repeat(3,minmax(0,1fr))}}@media(max-width:650px){main{padding:25px 4vw 45px}.intro{display:block}.intro h1{font-size:34px}.identity-card{margin-top:22px;padding:14px 18px}.identity-card p{margin:2px 0}.topbar{display:block}.topbar nav{margin-top:12px;justify-content:flex-start;gap:18px}.brand small{font-size:10px}.intro p{font-size:13px}.course-nav #courseNav{grid-template-columns:1fr}.nav-group{margin-top:14px}.course-link{font-size:13px;display:inline-flex;width:auto;margin-right:5px;padding:7px 10px;border:1px solid #e1ebf0}.nav-group h3{margin-left:3px}.panel{padding:19px 15px}.panel h2{font-size:21px}.task-list{grid-template-columns:1fr}.atlas-workspace{grid-template-columns:1fr}.stage{min-height:370px}.stage canvas{height:410px}.structure-panel #structureList{height:155px;display:grid;grid-template-columns:1fr 1fr;align-content:start;gap:3px}.structure-item{align-self:start}.atlas-toolbar{gap:10px}.mechanism-inner{grid-template-columns:1fr}.mechanism-inner>div{padding:0 8px}.section-title{align-items:flex-start}.section-title>a{max-width:110px;text-align:right}.record-actions{gap:9px}footer{flex-wrap:wrap;font-size:10px}}
/* Keep every course reachable when the desktop navigation exceeds the viewport. */
.course-nav{max-height:calc(100dvh - 36px);overflow:auto;overscroll-behavior:contain}
@media(max-width:900px){.course-nav{max-height:none;overflow:visible;overscroll-behavior:auto}}