/* Orbit Code 2026 UI + responsive/performance layer */
html,body{overflow-x:hidden}
.top .wrap{gap:14px}
.top nav{align-items:center;flex-wrap:wrap}
.top nav a.nav-pill{border:1px solid var(--line);padding:7px 11px;border-radius:999px;color:var(--ink);background:rgba(120,140,255,.06)}
.top nav a.nav-pill.primary{border-color:rgba(94,231,255,.45);background:rgba(94,231,255,.08)}
.langbar .wrap{scroll-snap-type:x proximity;overscroll-behavior-x:contain;-webkit-overflow-scrolling:touch;touch-action:pan-x;scroll-padding-inline:20px}
.langbar a{scroll-snap-align:center}
.langbar .wrap::-webkit-scrollbar{height:4px}
.langbar .wrap::-webkit-scrollbar-thumb{background:rgba(130,150,255,.35);border-radius:99px}
.course-tools{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin:14px 0}
.account-chip{display:inline-flex;align-items:center;gap:7px;border:1px solid var(--line);border-radius:999px;padding:7px 11px;color:var(--mute);font-size:.82rem;max-width:210px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.orbit-stable{contain:layout paint;will-change:transform}.orbitbox{contain:layout paint}
/* Avoid expensive backdrop blur on very small/slow screens while keeping the design. */
@media(max-width:600px){header.top{backdrop-filter:none;-webkit-backdrop-filter:none}.langbar{backdrop-filter:none;-webkit-backdrop-filter:none}.orbitbox{width:min(82vw,340px)}.top .wrap{height:auto;min-height:60px;padding-top:9px;padding-bottom:9px}.top nav{gap:6px}.top nav a{font-size:.8rem}.course-tools{align-items:stretch}.course-tools .btn{flex:1 1 auto;justify-content:center}}
@media(prefers-reduced-motion:reduce){.orbit{animation:none!important}.chip{animation:none!important}}
.modal-backdrop{position:fixed;inset:0;z-index:200;background:rgba(2,4,12,.78);display:grid;place-items:center;padding:18px;opacity:0;pointer-events:none;transition:opacity .18s ease}.modal-backdrop.open{opacity:1;pointer-events:auto}.modal{width:min(680px,100%);max-height:min(88vh,760px);overflow:auto;background:#0b1030;border:1px solid var(--line);border-radius:20px;box-shadow:0 30px 100px rgba(0,0,0,.55);padding:22px}.modal-head{display:flex;align-items:flex-start;justify-content:space-between;gap:14px}.modal h2{margin:0 0 6px}.modal .close{border:1px solid var(--line);background:transparent;border-radius:10px;padding:7px 10px}.auth-form{display:grid;gap:11px;margin-top:16px}.auth-form input{font:inherit;color:var(--ink);background:#080d26;border:1px solid var(--line);border-radius:10px;padding:11px 13px}.auth-actions{display:flex;gap:9px;flex-wrap:wrap;margin-top:12px}.muted{color:var(--mute);font-size:.88rem}.status-line{min-height:1.3em;color:var(--mute);font-size:.85rem}
/* Mobile reading: vertical scrolling everywhere except the Courses language bar. */
html,body{max-width:100%;overflow-x:hidden;overscroll-behavior-x:none}
body{touch-action:pan-y}
img,svg,video,iframe{max-width:100%;height:auto}
.prose,.main,.layout,.wrap,.card,.chapter,.note,.hero-course{min-width:0;max-width:100%}
.prose{overflow-wrap:anywhere}
figure.code pre{white-space:pre-wrap;overflow-x:hidden;overflow-wrap:anywhere;word-break:break-word}
.tablewrap{overflow-x:hidden;max-width:100%}
.prose table{min-width:0;width:100%;table-layout:fixed;word-break:break-word;overflow-wrap:anywhere}
.prose th,.prose td{overflow-wrap:anywhere;word-break:break-word}
.langbar .wrap{touch-action:pan-x;overscroll-behavior-x:contain}
@media(max-width:940px){
  .wrap{padding-left:14px;padding-right:14px}
  .layout{display:block}
  .toc{width:100%;max-width:none;overflow:visible}
  .prose{max-width:none;width:100%;font-size:1rem;line-height:1.75}
  .prose p,.prose li{overflow-wrap:anywhere}
  .top nav{flex-wrap:wrap;min-width:0}
  .top nav a{white-space:normal}
}
@media(max-width:600px){
  .grid{grid-template-columns:1fr}
  .card{padding:17px}
  .hero-course h1{font-size:clamp(1.8rem,9vw,2.5rem)}
  figure.code pre{font-size:.8rem;line-height:1.55;padding:12px}
  .prose table{font-size:.84rem}
}