/* Case study frame. Measurements follow iamnoman.com/notch and /transit:
   600px column, Inter 14/21, sections 55px apart, demo 13px under the text,
   hint row 8px under the demo. Dark mode is added for brianzhou.org. */

:root {
  color-scheme: light;
  --bg: #ffffff;
  --ink: #1b1c1d;
  --ink-2: #525252;
  --muted: #999999;
  --frame: #f4f3f0;
  --frame-2: #eae9e4;
  --ctl: #fafafa;
  --ctl-hover: #f0f0f0;
  --btn: #27272a;
  --btn-ink: #ffffff;
  --link-u: rgba(0, 0, 0, 0.15);
  --link-u-hover: rgba(0, 0, 0, 0.5);
  --sel: rgba(0, 0, 170, 0.2);
  --card: #ffffff;
  --card-edge: rgba(0, 0, 0, 0.06);
  --sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #000000;
    --ink: #ededed;
    --ink-2: #a3a3a3;
    --muted: #737373;
    --frame: #111111;
    --frame-2: #1c1c1c;
    --ctl: #141414;
    --ctl-hover: #1c1c1c;
    --btn: #ededed;
    --btn-ink: #000000;
    --link-u: rgba(255, 255, 255, 0.2);
    --link-u-hover: rgba(255, 255, 255, 0.55);
    --sel: rgba(120, 150, 255, 0.3);
    --card: #0f0f0f;
    --card-edge: rgba(255, 255, 255, 0.07);
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #000000;
  --ink: #ededed;
  --ink-2: #a3a3a3;
  --muted: #737373;
  --frame: #111111;
  --frame-2: #1c1c1c;
  --ctl: #141414;
  --ctl-hover: #1c1c1c;
  --btn: #ededed;
  --btn-ink: #000000;
  --link-u: rgba(255, 255, 255, 0.2);
  --link-u-hover: rgba(255, 255, 255, 0.55);
  --sel: rgba(120, 150, 255, 0.3);
  --card: #0f0f0f;
  --card-edge: rgba(255, 255, 255, 0.07);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 400 14px/21px var(--sans);
  letter-spacing: -0.08px;
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
}
::selection { background: var(--sel); color: var(--ink); }
button { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; border-radius: 6px; }

/* site header: brianzhou.org's "brian/path" on the left, its sections in the
   middle, a theme icon on the right. No rule under it; the page shows through. */
.cs-bar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: 48px; padding: 0 20px;
  display: grid; grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr); align-items: center; gap: 16px;
  background: color-mix(in srgb, var(--bg) 84%, transparent);
  -webkit-backdrop-filter: saturate(1.6) blur(16px); backdrop-filter: saturate(1.6) blur(16px);
}
.cs-crumbs { display: flex; align-items: center; min-width: 0; white-space: nowrap; font: 600 14px/20px var(--sans); letter-spacing: -0.18px; }
.cs-crumbs a { color: inherit; text-decoration: none; }
.cs-crumbs .path { min-width: 0; overflow: hidden; text-overflow: ellipsis; opacity: 0.5; }
.cs-crumbs .path a { transition: opacity 0.2s; }
.cs-crumbs .path:hover { opacity: 1; }
.cs-nav { display: flex; align-items: center; gap: 22px; font: 500 13px/18px var(--sans); letter-spacing: -0.08px; }
.cs-nav a { color: var(--muted); text-decoration: none; transition: color 0.2s; }
.cs-nav a:hover, .cs-nav a[aria-current] { color: var(--ink); }
.cs-tools { justify-self: end; display: flex; align-items: center; gap: 2px; margin-right: -6px; }
.cs-ib {
  width: 30px; height: 30px; padding: 0; border: 0; border-radius: 999px;
  display: grid; place-items: center; background: none; color: var(--ink-2); cursor: pointer;
  transition: background 0.2s, color 0.2s;
}
.cs-ib:hover, .cs-bar.menu-open .cs-menu { background: var(--ctl-hover); color: var(--ink); }
.cs-ib svg { width: 18px; height: 18px; overflow: visible; transition: transform 0.2s; }
.cs-ib:active svg { transform: scale(0.82); }
.cs-cmdk svg { width: 15px; height: 15px; }
/* the menu's three bars fold into an X */
.cs-menu path { transform-origin: 12px 12px; transition: transform 0.45s cubic-bezier(0.34, 1.45, 0.64, 1); }
.cs-menu .l2 { transition: transform 0.3s, opacity 0.2s; }
.cs-bar.menu-open .cs-menu .l1 { transform: rotate(45deg) translateY(5.5px); }
.cs-bar.menu-open .cs-menu .l2 { transform: scaleX(0.2); opacity: 0; }
.cs-bar.menu-open .cs-menu .l3 { transform: rotate(-45deg) translateY(-5.5px); }
/* light shows the moon; dark turns it into the sun */
.cs-theme .orb { transform-box: fill-box; transform-origin: center; transition: transform 0.55s cubic-bezier(0.34, 1.45, 0.64, 1); }
.cs-theme .cut { transition: transform 0.55s cubic-bezier(0.34, 1.2, 0.64, 1); }
.cs-theme .rays { transform-origin: 12px 12px; transform: rotate(-90deg) scale(0.3); opacity: 0; transition: transform 0.55s cubic-bezier(0.34, 1.45, 0.64, 1), opacity 0.25s; }
:root[data-theme="dark"] .cs-theme .orb { transform: scale(0.58); }
:root[data-theme="dark"] .cs-theme .cut { transform: translate(10px, -10px); }
:root[data-theme="dark"] .cs-theme .rays { transform: none; opacity: 1; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .cs-theme .orb { transform: scale(0.58); }
  :root:not([data-theme="light"]) .cs-theme .cut { transform: translate(10px, -10px); }
  :root:not([data-theme="light"]) .cs-theme .rays { transform: none; opacity: 1; }
}
@media (max-width: 760px) { .cs-bar { grid-template-columns: minmax(0, 1fr) auto; padding: 0 16px; } .cs-nav { display: none; } }

/* menu: a card under the menu button; space, not rules, splits the three groups */
.cs-pop {
  position: absolute; top: 44px; right: 14px; width: 208px; padding: 5px;
  border-radius: 12px; background: var(--card);
  box-shadow: 0 0 0 1px var(--card-edge), 0 12px 32px rgba(0, 0, 0, 0.1), 0 2px 6px rgba(0, 0, 0, 0.04);
  transform-origin: top right; transform: translateY(-4px) scale(0.96); opacity: 0;
  transition: transform 0.18s cubic-bezier(0.2, 0.9, 0.3, 1.2), opacity 0.14s;
}
.cs-pop.in { transform: none; opacity: 1; }
.cs-pop .grp + .grp { margin-top: 9px; }
.cs-pop a {
  display: flex; align-items: center; gap: 11px; height: 32px; padding: 0 10px; border-radius: 7px;
  color: var(--ink-2); text-decoration: none; font: 500 13px/18px var(--sans); letter-spacing: -0.08px;
  opacity: 0; transform: translateY(-3px); transition: background 0.15s, color 0.15s, opacity 0.2s, transform 0.25s;
}
.cs-pop.in a { opacity: 1; transform: none; transition-delay: 0s, 0s, calc(var(--i) * 14ms), calc(var(--i) * 14ms); }
.cs-pop a svg { width: 15px; height: 15px; flex: none; color: var(--muted); transition: color 0.15s; }
.cs-pop a:hover, .cs-pop a:focus-visible { background: var(--ctl-hover); color: var(--ink); outline: none; }
.cs-pop a:hover svg, .cs-pop a:focus-visible svg, .cs-pop a[aria-current] svg { color: var(--ink); }
.cs-pop a[aria-current] { color: var(--ink); }

/* ⌘K: a search box over a dimmed page; one highlight slides between rows */
.cs-k { position: fixed; inset: 0; z-index: 200; }
.cs-k-scrim { position: absolute; inset: 0; background: rgba(15, 18, 24, 0.18); opacity: 0; transition: opacity 0.16s; }
.cs-k-box {
  position: absolute; left: 50%; top: 13vh; width: min(560px, calc(100vw - 24px));
  display: flex; flex-direction: column; max-height: min(500px, 74vh);
  border-radius: 14px; background: var(--card); overflow: hidden;
  box-shadow: 0 0 0 1px var(--card-edge), 0 24px 70px rgba(0, 0, 0, 0.16), 0 4px 12px rgba(0, 0, 0, 0.05);
  transform: translateX(-50%) translateY(-6px) scale(0.975); opacity: 0;
  transition: transform 0.2s cubic-bezier(0.2, 0.9, 0.3, 1.15), opacity 0.14s;
}
.cs-k.in .cs-k-scrim { opacity: 1; }
.cs-k.in .cs-k-box { transform: translateX(-50%); opacity: 1; }
.cs-k-in { display: flex; align-items: center; gap: 12px; height: 52px; padding: 0 16px 0 18px; flex: none; }
.cs-k-in svg { width: 17px; height: 17px; color: var(--muted); flex: none; }
.cs-k-in input { flex: 1; min-width: 0; height: 100%; border: 0; outline: none; background: none; color: var(--ink); font: 400 15px/22px var(--sans); letter-spacing: -0.2px; }
.cs-k-in input::placeholder { color: var(--muted); }
.cs-k kbd { display: inline-grid; place-items: center; min-width: 20px; height: 20px; padding: 0 5px; border-radius: 5px; background: var(--frame); color: var(--muted); font: 500 11px/1 var(--sans); }
.cs-k-list { position: relative; flex: 1; min-height: 0; overflow-y: auto; overscroll-behavior: contain; padding: 0 8px 8px; }
.cs-k-hl { position: absolute; left: 8px; right: 8px; top: 0; border-radius: 9px; background: var(--ctl-hover); pointer-events: none; }
.cs-k-hl.slide { transition: transform 0.16s cubic-bezier(0.2, 0.9, 0.3, 1.1), height 0.16s; }
.cs-k-rows { position: relative; }
.cs-k-h { padding: 12px 10px 5px; font: 500 11.5px/16px var(--sans); color: var(--muted); }
.cs-k-row { display: flex; align-items: center; gap: 12px; height: 42px; padding: 0 10px; border-radius: 9px; cursor: pointer; color: var(--ink-2); font: 500 13.5px/18px var(--sans); letter-spacing: -0.1px; }
.cs-k-row[aria-selected] { color: var(--ink); }
.cs-k-row .ic { display: grid; place-items: center; width: 26px; height: 26px; border-radius: 7px; background: var(--frame); color: var(--ink-2); flex: none; font-style: normal; }
.cs-k-row .ic svg { width: 14px; height: 14px; }
.cs-k-row .ic-moon { background: #eef0ff; color: #5b5bd6; }
.cs-k-row .ic-sun { background: rgba(255, 196, 0, 0.14); color: #f5b400; }
.cs-k-row .ic-copy { background: #e8f7ef; color: #16a34a; }
.cs-k-row .ic-github { background: var(--ink); color: var(--bg); }
.cs-k-row .ic-linkedin { background: #0a66c2; color: #fff; }
.cs-k-row .t { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.cs-k-row .m { margin-left: auto; padding-left: 12px; color: var(--muted); font: 400 12px/16px var(--sans); white-space: nowrap; }
.cs-k-row .m svg { width: 14px; height: 14px; display: block; }
.cs-k-row.cur .m { font-size: 0; } .cs-k-row.cur .m::after { content: "this page"; font-size: 12px; }
.cs-k-none { padding: 28px 10px 22px; text-align: center; color: var(--muted); font: 400 13px/18px var(--sans); }
.cs-k-foot { flex: none; display: flex; align-items: center; gap: 16px; height: 38px; padding: 0 16px; background: var(--frame); color: var(--muted); font: 400 11.5px/16px var(--sans); }
.cs-k-foot span { display: inline-flex; align-items: center; gap: 4px; }
.cs-k-foot kbd { background: var(--card); min-width: 18px; height: 18px; }
.cs-k-foot .r { margin-left: auto; }
html.cs-k-lock { overflow: hidden; }
@media (max-width: 640px) { .cs-k-box { top: 10px; } .cs-k-foot { display: none; } .cs-k-in kbd { display: none; } }
:root[data-theme="dark"] .cs-k-scrim { background: rgba(0, 0, 0, 0.5); }
:root[data-theme="dark"] .cs-pop, :root[data-theme="dark"] .cs-k-box { background: #0f0f0f; box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.08), 0 24px 70px rgba(0, 0, 0, 0.5); }
:root[data-theme="dark"] .cs-k-row .ic-moon, :root[data-theme="dark"] .cs-k-row .ic-sun { background: rgba(255, 196, 0, 0.12); color: #fbbf24; }
:root[data-theme="dark"] .cs-k-row .ic-copy { background: rgba(34, 197, 94, 0.14); color: #4ade80; }
:root[data-theme="dark"] .cs-k-hl, :root[data-theme="dark"] .cs-pop a:hover, :root[data-theme="dark"] .cs-pop a:focus-visible { background: #1c1c1c; }
:root[data-theme="dark"] .cs-k kbd { background: #1c1c1c; }
:root[data-theme="dark"] .cs-k-foot { background: #171717; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .cs-k-scrim { background: rgba(0, 0, 0, 0.5); }
  :root:not([data-theme="light"]) .cs-pop, :root:not([data-theme="light"]) .cs-k-box { background: #0f0f0f; box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.08), 0 24px 70px rgba(0, 0, 0, 0.5); }
  :root:not([data-theme="light"]) .cs-k-row .ic-moon, :root:not([data-theme="light"]) .cs-k-row .ic-sun { background: rgba(255, 196, 0, 0.12); color: #fbbf24; }
  :root:not([data-theme="light"]) .cs-k-row .ic-copy { background: rgba(34, 197, 94, 0.14); color: #4ade80; }
  :root:not([data-theme="light"]) .cs-k-hl, :root:not([data-theme="light"]) .cs-pop a:hover, :root:not([data-theme="light"]) .cs-pop a:focus-visible { background: #1c1c1c; }
  :root:not([data-theme="light"]) .cs-k kbd { background: #1c1c1c; }
  :root:not([data-theme="light"]) .cs-k-foot { background: #171717; }
}

.cs-main { padding: 144px 24px 89px; min-height: 100vh; }
.cs-main.has-hero { padding-top: 60px; }
.cs-col { max-width: 600px; margin: 0 auto; }

.cs-title { margin: 0 0 5px; font: 500 15px/22px var(--sans); letter-spacing: -0.26px; text-wrap: pretty; }
.cs-intro p { margin: 0; font: 400 15px/22px var(--sans); letter-spacing: -0.26px; text-wrap: pretty; }
.cs-intro p + p { margin-top: 13px; }

a.cs-link {
  color: inherit; text-decoration: underline; text-decoration-color: var(--link-u);
  text-underline-offset: 2px; transition: text-decoration-color 0.2s;
}
a.cs-link:hover { text-decoration-color: var(--link-u-hover); }

.cs-sec { margin-top: 55px; }
.cs-sec h2 { margin: 0; font: 500 14px/21px var(--sans); letter-spacing: -0.08px; text-wrap: pretty; }
.cs-sec > p, .cs-sec .cs-text p { margin: 5px 0 0; text-wrap: pretty; }
.cs-sec code { font: 12.5px var(--mono); }

.cs-demo { margin-top: 13px; }
.cs-frame {
  position: relative; width: 100%; height: var(--h, 400px);
  overflow: hidden; border-radius: 8px; background: var(--frame);
  touch-action: pan-y;
}
.cs-frame.auto { height: auto; }
.cs-row {
  margin-top: 8px; min-height: 28px;
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
}
.cs-hint { font: 400 13px/18px var(--sans); color: var(--muted); user-select: none; }
.cs-hint b { font-weight: 400; color: var(--ink-2); font-variant-numeric: tabular-nums; }
.cs-ctls { display: flex; align-items: center; gap: 8px; margin-left: auto; }

/* controls */
.cs-btn {
  height: 28px; padding: 0 8px; border: 0; border-radius: 999px; cursor: pointer;
  background: var(--btn); color: var(--btn-ink);
  font: 500 13px/18px var(--sans); letter-spacing: -0.08px; user-select: none; white-space: nowrap;
  transition: opacity 150ms ease, background 150ms ease;
}
.cs-btn.quiet { background: var(--ctl); color: var(--ink-2); }
.cs-btn:active { opacity: 0.7; }
@media (hover: hover) { .cs-btn:hover { opacity: 0.85; } }

.cs-seg {
  position: relative; display: inline-flex; align-items: center; gap: 2px;
  height: 28px; padding: 2px; border-radius: 999px; background: var(--ctl);
}
.cs-seg.bare { background: transparent; }
.cs-seg button {
  position: relative; z-index: 1; height: 100%; padding: 0 8px; border: 0; border-radius: 999px;
  background: transparent; cursor: pointer; white-space: nowrap; user-select: none;
  font: 500 13px/18px var(--sans); letter-spacing: -0.08px; color: var(--ink);
  transition: color 150ms ease;
}
.cs-seg button[aria-pressed="true"] { color: var(--btn-ink); }
.cs-seg .cs-pill {
  position: absolute; top: 2px; bottom: 2px; left: 0; width: 0; border-radius: 999px;
  background: var(--btn); pointer-events: none;
}

.cs-toggle { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; font: 500 13px/18px var(--sans); color: var(--ink-2); user-select: none; border: 0; background: none; padding: 0; }
.cs-toggle i { position: relative; width: 26px; height: 16px; border-radius: 8px; background: var(--frame-2); transition: background 0.2s; }
.cs-toggle i::after { content: ""; position: absolute; top: 2px; left: 2px; width: 12px; height: 12px; border-radius: 6px; background: var(--bg); transition: transform 0.25s cubic-bezier(.34,1.45,.64,1); }
.cs-toggle[aria-pressed="true"] i { background: var(--btn); }
.cs-toggle[aria-pressed="true"] i::after { transform: translateX(10px); }

/* hero: the product running by itself */
.cs-hero { position: relative; max-width: 1200px; margin: 0 auto 40px; height: 72vh; min-height: 420px; max-height: 720px; }
.cs-hero-in { position: relative; width: 100%; height: 100%; overflow: hidden; border-radius: 18px; isolation: isolate; }
.cs-hero-fade { position: absolute; left: 0; right: 0; bottom: 0; height: 34%; pointer-events: none; z-index: 5; background: linear-gradient(to bottom, transparent, var(--bg)); }

/* toast */
.cs-toast {
  position: absolute; left: 50%; bottom: 14px; z-index: 20; transform: translate(-50%, 12px); opacity: 0;
  height: 28px; padding: 0 12px; border-radius: 14px; display: flex; align-items: center;
  background: var(--btn); color: var(--btn-ink); font: 500 12px/16px var(--sans); white-space: nowrap;
  pointer-events: none;
}

/* ending */
.cs-end { margin-top: 55px; }
.cs-next { margin-top: 89px; display: flex; justify-content: space-between; gap: 16px; font: 500 13px/18px var(--sans); }
.cs-next a { color: var(--muted); text-decoration: none; }
.cs-next a:hover { color: var(--ink); }

/* ?embed: the hero alone, filling the frame */
html.cs-embed, html.cs-embed body { background: transparent; overflow: hidden; }
html.cs-embed .cs-bar, html.cs-embed .cs-col, html.cs-embed .cs-hero-fade, html.cs-embed #cs-pixels { display: none; }
html.cs-embed .cs-main, html.cs-embed .cs-main.has-hero { padding: 0; min-height: 0; }
html.cs-embed .cs-hero { max-width: none; height: 100vh; min-height: 0; max-height: none; margin: 0; }
html.cs-embed .cs-hero-in { border-radius: 0; }

#cs-pixels { position: fixed; inset: 0; width: 100vw; height: 100vh; pointer-events: none; z-index: 90; image-rendering: pixelated; }

@media (max-width: 640px) {
  .cs-main { padding: 96px 16px 48px; }
  .cs-main.has-hero { padding-top: 60px; }
  .cs-frame { height: min(var(--h, 400px), 320px); }
  .cs-frame.keep { height: var(--h, 400px); }
  .cs-hero { height: 50vh; min-height: 300px; max-height: 400px; margin-bottom: 8px; }
  .cs-hero-in { border-radius: 12px; }
  .cs-row { flex-wrap: wrap; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; }
}