/* The complete directory is deliberately lightweight: illustrations add no WebGL contexts. */
.catalog-section{padding-block:62px 74px;border-top:1px solid var(--line);scroll-margin-top:28px}.catalog-heading{display:flex;align-items:end;justify-content:space-between;gap:32px;margin-bottom:27px}.catalog-heading .eyebrow{margin-bottom:12px}.catalog-heading>p{max-width:400px;color:var(--muted);font-size:12px;line-height:1.9;margin:0 0 2px}.catalog-toolbar{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-bottom:23px}.catalog-filters{display:flex;gap:7px;flex-wrap:wrap}.catalog-filters button{font:inherit;font-size:11px;line-height:1.4;padding:10px 16px;min-height:38px;border:1px solid #d9e0d4;border-radius:99px;background:transparent;color:#5d746a;cursor:pointer;transition:background .15s,color .15s}.catalog-filters button[aria-pressed=true]{background:var(--ink);border-color:var(--ink);color:#fff}.catalog-filters button:hover:not([aria-pressed=true]){background:#eaf0e5}.catalog-filters button:focus-visible{outline:3px solid #6da99b;outline-offset:3px}#catalog-count{font-size:11px;color:#7b8d80;white-space:nowrap;margin:0;font-variant-numeric:tabular-nums}.catalog-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px}.catalog-card{display:flex;flex-direction:column;min-width:0;overflow:hidden;background:#fffef8;border:1px solid #dfe5d9;border-radius:8px;text-decoration:none;color:var(--ink);transition:transform .17s,box-shadow .17s,border-color .17s}.catalog-card[hidden]{display:none}.catalog-card:hover{transform:translateY(-3px);box-shadow:0 12px 24px #17372d0c;border-color:#b5cbbf}.catalog-card:focus-visible{outline:3px solid #458d83;outline-offset:4px}.catalog-figure{position:relative;overflow:hidden;aspect-ratio:320/160;background:radial-gradient(ellipse at 44% 35%,#2e505c,#163141 78%)}.catalog-figure svg{display:block;width:100%;height:100%;padding:0 32px}.catalog-figure-solar{background:radial-gradient(ellipse at 50% 50%,#2b3851,#101c30 80%)}.catalog-figure-cube,.catalog-figure-cylinder{background:radial-gradient(ellipse at 44% 35%,#325c5d,#143742 80%)}.catalog-figure-energy,.catalog-figure-lever{background:radial-gradient(ellipse at 44% 35%,#534f45,#273541 80%)}.catalog-figure-lens,.catalog-figure-lens3d{background:radial-gradient(ellipse at 44% 35%,#36506b,#1a2d42 80%)}.catalog-dimension{position:absolute;left:17px;top:14px;font-size:9px;letter-spacing:.6px;border:1px solid #c9e3df55;border-radius:4px;color:#d7ece3;padding:4px 6px;line-height:1}.catalog-sequence{position:absolute;right:17px;bottom:14px;color:#9bb9bf;font-size:9px;letter-spacing:1px;font-variant-numeric:tabular-nums}.catalog-body{display:flex;flex:1;flex-direction:column;padding:20px 22px 21px}.catalog-meta{display:flex;align-items:center;justify-content:space-between;gap:9px;margin-bottom:13px;color:#759080;font-size:9px}.catalog-language{color:#8b8e7f;font-size:8px}.catalog-language.bilingual{color:#4e8676}.catalog-body h3{font-family:var(--serif);font-size:24px;font-weight:400;line-height:1.2;letter-spacing:-.3px;margin:0 0 13px}.catalog-body>p{font-size:11px;line-height:1.85;color:#6b7d73;margin:0 0 21px;min-height:40px}.catalog-enter{display:flex;align-items:center;justify-content:space-between;border-top:1px solid #e3e9dc;padding-top:15px;margin-top:auto;font-size:10px;font-weight:550;color:#367260}.catalog-enter>span{font-size:16px}.catalog-note{font-size:10px;color:#819083;line-height:1.9;margin:21px 0 0}html[lang=zh-CN] .catalog-body h3{font-family:var(--sans);font-size:20px;line-height:1.45;font-weight:500;letter-spacing:0}
@media(max-width:1080px){.catalog-grid{gap:17px}.catalog-body{padding:18px}.catalog-body h3{font-size:22px}.catalog-figure svg{padding-inline:18px}.catalog-meta{font-size:8px}.catalog-heading>p{max-width:350px}}
@media(max-width:780px){.catalog-section{padding-block:44px 49px}.catalog-heading{align-items:start;flex-direction:column;gap:16px}.catalog-heading>p{max-width:530px;font-size:12px}.catalog-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:17px}.catalog-figure{aspect-ratio:320/180}.catalog-body{padding:18px}.catalog-body h3{font-size:23px}.catalog-filters button{padding:10px 14px}.catalog-toolbar{align-items:start;gap:12px}#catalog-count{padding-top:12px}}
/* Mobile cards keep the full landscape illustration above the text. */
@media(max-width:520px){.catalog-section{padding-block:39px 43px}.catalog-heading{gap:14px;margin-bottom:23px}.catalog-heading .eyebrow{font-size:8px;letter-spacing:1.5px}.catalog-heading>p{font-size:11px;line-height:1.9;max-width:330px}.catalog-toolbar{gap:12px;flex-direction:column;margin-bottom:20px}.catalog-filters{gap:6px;width:100%}.catalog-filters button{font-size:10px;min-height:38px;padding:10px 13px}#catalog-count{font-size:10px}.catalog-grid{grid-template-columns:1fr;gap:18px}.catalog-card{display:flex;flex-direction:column}.catalog-figure{height:auto;min-height:0;aspect-ratio:16/9}.catalog-figure svg{position:absolute;inset:0;width:100%;height:100%;padding:10px 22px}.catalog-dimension{left:11px;top:12px;font-size:8px;padding:3px 4px}.catalog-sequence{right:11px;bottom:12px;font-size:8px}.catalog-body{padding:18px 16px;min-width:0}.catalog-meta{font-size:8px;gap:6px;margin-bottom:11px;flex-wrap:wrap}.catalog-language{font-size:7px}.catalog-body h3{font-size:21px;line-height:1.2;margin-bottom:11px}.catalog-body>p{font-size:10px;line-height:1.8;min-height:0;margin-bottom:15px}.catalog-enter{font-size:9px;padding-top:12px}.catalog-note{font-size:9px;line-height:1.9;margin-top:18px}html[lang=zh-CN] .catalog-body h3{font-size:18px;line-height:1.45}}
@media(prefers-reduced-motion:reduce){.catalog-card,.catalog-filters button{transition:none}.catalog-card:hover{transform:none}}
/* A quiet availability marker keeps the free labs distinct from teacher resources. */
.catalog-kicker{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin-bottom:13px}.catalog-kicker .eyebrow{margin:0}.catalog-free{display:inline-flex;align-items:center;gap:6px;border:1px solid #c7dbcf;border-radius:99px;padding:5px 9px;background:#eaf2e7;color:#356c58;font-size:8px;font-weight:650;letter-spacing:.7px;line-height:1.2;white-space:nowrap}.catalog-free>span{font-size:10px;letter-spacing:0}.catalog-heading>div{min-width:0}.catalog-heading h2{max-width:590px}@media(max-width:520px){.catalog-kicker{gap:9px;margin-bottom:12px}.catalog-kicker .eyebrow{margin:0}.catalog-free{font-size:7px;letter-spacing:.5px;padding:5px 8px}.catalog-free>span{font-size:9px}.catalog-heading h2{font-size:29px;line-height:1.3}html[lang=zh-CN] .catalog-heading h2{font-size:27px;letter-spacing:-.7px}}
/* Separate student and teacher links keep both choices explicit and accessible. */
.catalog-figure{display:block;flex-shrink:0}.catalog-body h3 a{color:inherit;text-decoration:none}.catalog-body h3 a:hover{text-decoration:underline;text-underline-offset:4px}.catalog-card:focus-within{border-color:#8ab3a2}.catalog-body a:focus-visible{outline:3px solid #458d83;outline-offset:3px}.catalog-actions{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;border-top:1px solid #e3e9dc;padding-top:15px;margin-top:auto}.catalog-actions .catalog-enter{min-width:0;min-height:44px;margin:0;border:1px solid #9bb9aa;border-radius:5px;padding:10px 9px;gap:6px;font-size:9px;line-height:1.4;text-decoration:none;white-space:normal}.catalog-actions .catalog-enter>span{font-size:13px;flex-shrink:0}.catalog-actions .catalog-student{background:var(--ink);color:#fff;border-color:var(--ink)}.catalog-actions .catalog-student:hover{background:#285362}.catalog-actions .catalog-teacher{background:#edf3e9;color:#356c58}.catalog-actions .catalog-teacher:hover{background:#e0ebde}@media(max-width:520px){.catalog-actions{grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;padding-top:12px}.catalog-actions .catalog-enter{font-size:10px;padding:10px 11px;min-height:44px}}

.catalog-search{margin:28px 0 18px;max-width:650px}.catalog-search label{display:block;color:#496a62;font-size:12px;margin-bottom:10px}.catalog-search>div{display:flex;border:1px solid #cdd9ce;background:#fffef8;border-radius:8px;overflow:hidden}.catalog-search input{border:0;flex:1;min-width:0;background:transparent;padding:15px;font:inherit;font-size:14px;color:#193945;outline-offset:-3px}.catalog-search button{border:0;background:transparent;color:#497668;padding:10px 17px;cursor:pointer}.catalog-search input:focus-visible,.catalog-search button:focus-visible{outline:2px solid #33796b}#catalog-empty{padding:35px;background:#edf3e7;border-radius:9px;color:#5a7766}.catalog-actions .catalog-student{white-space:normal}

/* Stages and subjects are independent, composable filters. */
.catalog-filter-row{display:grid;grid-template-columns:84px minmax(0,1fr);align-items:center;gap:12px;min-width:0}.catalog-filter-label{font-size:11px;line-height:1.6;color:#6d8276;margin:0}.catalog-stage-row{margin-bottom:13px}.catalog-stage-filters button[aria-pressed=true]{background:#e1eddd;border-color:#8db496;color:#275e44}.catalog-toolbar{margin-bottom:0}.catalog-stage-note{font-size:10px;color:#7d8e7e;line-height:1.8;margin:15px 0 23px}.catalog-stage-tag{font-size:9px;color:#4c8068;line-height:1.7;margin:0 0 9px;letter-spacing:.1px}.catalog-search{margin-bottom:23px}@media(max-width:780px){.catalog-filter-row{grid-template-columns:78px minmax(0,1fr);gap:10px}}@media(max-width:520px){.catalog-filter-row{grid-template-columns:1fr;gap:9px;width:100%}.catalog-filter-label{font-size:10px}.catalog-stage-row{margin-bottom:17px}.catalog-stage-filters{gap:7px}.catalog-stage-filters button{padding:10px 15px}.catalog-toolbar{margin-bottom:0;gap:3px}.catalog-stage-note{font-size:9px;margin:12px 0 20px}.catalog-stage-tag{font-size:8px}.catalog-toolbar #catalog-count{padding-top:8px}}