:root{--ui-canvas:#ffffff;--ui-surface:#ffffff;--ui-soft:#f5f5f3;--ui-text:#1b1b1b;--ui-text-secondary:#848484;--ui-border:#eeeeec;--ui-brand:#ff692d;--ui-brand-text:#b94717;--ui-brand-soft:#fff1e9;--ui-on-brand:#ffffff;--ui-action-primary:#1b1b1b;--ui-on-action-primary:#ffffff;--ui-action-primary-hover:#383838;--ui-ink:#111214;--ui-ink-soft:#1b1d20;--ui-brand-hover:#ff7d49;--ui-shadow-card:0 18px 48px rgb(17 18 20/0.14);--ui-focus-ring:#2865d8;--ui-danger:#b42318;--ui-success:#217a42;--ui-radius-sm:8px;--ui-radius-md:12px;--ui-radius-lg:18px;--ui-control-height:40px;--ui-control-height-compact:32px;--ui-control-hover-bg:var(--ui-brand-soft);--ui-control-hover-fg:var(--ui-brand-text);--ui-control-hover-border:#ffd7c4;--ui-duration-fast:120ms;--ui-duration-normal:180ms;--ui-duration-slow:240ms;--ui-ease-standard:cubic-bezier(0.2,0,0,1);--ui-ease:var(--ui-duration-normal) var(--ui-ease-standard);--ui-overlay:rgb(32 33 31/0.38);--ui-overlay-button-bg:rgb(255 255 255/0.92);--ui-overlay-button-text:#20211f;--ui-overlay-button-hover:#ffffff;--ui-tooltip-bg:#20211f;--ui-tooltip-text:#ffffff;--ui-shadow-popover:0 8px 24px rgb(32 33 31/0.12);--ui-shadow-tooltip:0 4px 12px rgb(32 33 31/0.18);--ui-z-sticky:10;--ui-z-dropdown:30;--ui-z-overlay:50;--ui-z-dialog:60;--ui-z-toast:80;--ui-z-tooltip:90;--accent:var(--ui-brand);--accent-dark:var(--ui-brand-text);--coral:var(--ui-brand);--coral-dark:var(--ui-brand-text);--ink:var(--ui-text);--muted:var(--ui-text-secondary);--line:var(--ui-border);--paper:var(--ui-surface);--canvas:var(--ui-canvas);--soft:var(--ui-soft);--radius:var(--ui-radius-sm);--sidebar:228px;--topbar:80px;--shadow:var(--ui-shadow-popover);--danger:var(--ui-danger);--success:var(--ui-success)}*{box-sizing:border-box}html{scroll-behavior:smooth;scrollbar-gutter:stable}body{margin:0;font-family:Inter,Helvetica Neue,PingFang SC,Microsoft YaHei,sans-serif;font-size:14px;-webkit-font-smoothing:antialiased}button{color:inherit;background:none;border:0;padding:0}a,button,button:not(:disabled){cursor:pointer}.mock-banner{position:relative;z-index:80;padding:6px 16px;background:#fff3cf;color:#5e4510;text-align:center;font-size:12px;border-bottom:1px solid #e7cc7d}a{color:inherit;text-decoration:none}button,input,select,textarea{font:inherit}a,button{-webkit-tap-highlight-color:transparent}img{display:block;max-width:100%}.container{width:min(100% - 40px,1480px);margin-inline:auto}.page-shell{padding:20px 0 72px;min-height:60vh}.page-title{margin:0;font-size:22px;font-weight:650;letter-spacing:-.02em}.page-lede{max-width:640px;margin:8px 0 0;color:var(--muted);font-size:13px;line-height:1.7}.eyebrow{margin:0 0 8px;color:var(--muted);font-size:12px}.section-head{display:flex;align-items:center;justify-content:space-between;gap:16px;margin-bottom:16px}.section-head h2{margin:0;font-size:16px;font-weight:650}.section-head a{color:var(--muted);font-size:13px}.button{display:inline-flex;min-height:36px;align-items:center;justify-content:center;gap:6px;border:1px solid var(--ink);border-radius:6px;padding:0 14px;background:var(--ink);color:#fff;cursor:pointer;transition:transform .16s ease,background .16s ease}.button:hover{transform:translateY(-1px)}.button:active{transform:scale(.98)}.button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible{outline:2px solid var(--ui-focus-ring);outline-offset:4px}.button.coral{border-color:var(--accent);background:var(--accent)}.button.secondary{background:#fff;color:var(--ink);border-color:var(--line)}.button:disabled{opacity:.5;cursor:not-allowed;transform:none}.chip-row{display:flex;gap:8px;flex-wrap:wrap}.chip{border:1px solid var(--line);border-radius:999px;padding:6px 12px;background:#fff;color:#555;font-size:13px}.chip.active{border-color:var(--ink);background:var(--ink);color:#fff}.surface{border:1px solid var(--line);border-radius:var(--radius);background:#fff}.muted{color:var(--muted)}.solution-grid{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:20px 16px}.course-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:20px 16px}.creator-grid,.topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.status-state{display:grid;min-height:280px;place-items:center;text-align:center;border:1px dashed #ddd;border-radius:var(--radius);background:#fff;padding:40px}.status-state svg{color:var(--accent)}.status-state h2{margin:16px 0 8px;font-size:20px}.status-state p{max-width:480px;margin:0 0 20px;color:var(--muted);line-height:1.7}.skeleton{background:#ececec;animation:pulse 1.4s ease-in-out infinite alternate}@keyframes pulse{to{opacity:.5}}@media (max-width:1400px){.solution-grid{grid-template-columns:repeat(4,minmax(0,1fr))}}@media (max-width:1100px){.course-grid,.solution-grid{grid-template-columns:repeat(3,minmax(0,1fr))}}@media (max-width:800px){.container{width:calc(100% - 28px)}.course-grid,.solution-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:16px 12px}.creator-grid,.topic-grid{grid-template-columns:1fr}}@media (max-width:520px){.course-grid,.solution-grid{grid-template-columns:1fr}}@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,:after,:before{transition-duration:.01ms!important;animation-duration:.01ms!important}}:root[data-theme=dark]{--ui-canvas:#0b0d0f;--ui-surface:#121517;--ui-soft:#1b1f22;--ui-text:#f5f6f6;--ui-text-secondary:#9da4a8;--ui-border:#2c3236;--ui-brand:#ff6b2c;--ui-brand-text:#ff9a70;--ui-brand-soft:#321d16;--ui-action-primary:#ff6b2c;--ui-on-action-primary:#160d09;--ui-action-primary-hover:#ff824d;--ui-control-hover-border:#7b3d26;--ui-overlay:rgb(0 0 0/0.62);--ui-shadow-popover:0 18px 55px rgb(0 0 0/0.42);--ui-shadow-card:0 18px 48px rgb(0 0 0/0.35);--ink:var(--ui-text);--muted:var(--ui-text-secondary);--line:var(--ui-border);--paper:var(--ui-surface);--canvas:var(--ui-canvas);--soft:var(--ui-soft)}:root[data-theme=dark] .button.secondary,:root[data-theme=dark] .chip,:root[data-theme=dark] .status-state,:root[data-theme=dark] .surface{background:var(--ui-surface);color:var(--ui-text)}:root[data-theme=dark] .mock-banner{background:#2b2014;color:#ffd8b0;border-color:#6f4a2a}:root[data-theme=dark] input::placeholder{color:#7f898f}:root[data-theme=light]{--ui-canvas:#ffffff;--ui-surface:#ffffff;--ui-soft:#f5f5f3;--ui-text:#1b1b1b;--ui-text-secondary:#848484;--ui-border:#eeeeec;--ui-brand:#ff692d;--ui-brand-text:#b94717;--ui-brand-soft:#fff1e9;--ui-action-primary:#1b1b1b;--ui-on-action-primary:#ffffff;--ui-action-primary-hover:#383838;--ui-control-hover-border:#ffd7c4;--ui-overlay:rgb(32 33 31/.38);--ui-shadow-popover:0 8px 24px rgb(32 33 31/.12);--ui-shadow-card:0 18px 48px rgb(17 18 20/.14);--ink:var(--ui-text);--muted:var(--ui-text-secondary);--line:var(--ui-border);--paper:var(--ui-surface);--canvas:var(--ui-canvas);--soft:var(--ui-soft)}html{color-scheme:dark}html[data-theme=light]{color-scheme:light}body{background:var(--ui-canvas);color:var(--ui-text)}