/* Layout: a single column between two strips of film sprockets; the encode/decode panel is the working surface */
:root {
  --bg: #f4f1ec;
  --surface: #ffffff;
  --ink: #1d1a17;
  --muted: #6c645b;
  --line: #ddd5ca;
  --amber: #c26a00;
  --amber-soft: #fbe9d0;
  --ok: #2f7d4a;
  --bad: #b3362a;
  --display: "Unbounded", "Arial Black", sans-serif;
  --body: "IBM Plex Sans", "Helvetica Neue", Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131110; --surface: #1d1a18; --ink: #f1ebe3; --muted: #a39a8f; --line: #35302b;
    --amber: #ffb547; --amber-soft: #3a2a14; --ok: #6fcf8f; --bad: #ff8070;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body { background: var(--bg); color: var(--ink); font: 16px/1.55 var(--body); }

.sprockets {
  position: fixed; inset: 0 auto 0 0; width: 28px; pointer-events: none;
  background: radial-gradient(circle at 14px 14px, var(--line) 0 5px, transparent 5.5px) 0 0 / 28px 28px;
  opacity: .9;
}
.page { max-width: 720px; margin: 0 auto; padding: 56px 20px 80px 44px; display: grid; gap: 32px; }

.eyebrow { margin: 0; font: 500 12px var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
h1 { margin: 8px 0 12px; font: 800 clamp(44px, 9vw, 76px)/.95 var(--display); letter-spacing: -.03em; }
h1 span { color: var(--amber); }
.lede { margin: 0; max-width: 58ch; color: var(--muted); font-size: 18px; }

.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--line); }
.tab {
  font: 600 15px var(--body); color: var(--muted); background: none; border: 0; cursor: pointer;
  padding: 10px 16px; border-bottom: 3px solid transparent; margin-bottom: -1px;
}
.tab[aria-selected="true"] { color: var(--ink); border-color: var(--amber); }
.tab:focus-visible, .go:focus-visible, .clear:focus-visible { outline: 2px solid var(--amber); outline-offset: 2px; }

.panel { display: grid; gap: 18px; }
.drop {
  display: grid; place-items: center; gap: 4px; text-align: center; cursor: pointer;
  padding: 40px 20px; border: 2px dashed var(--line); border-radius: 14px; background: var(--surface);
  transition: border-color .15s, background .15s;
}
.drop:hover, .drop.over { border-color: var(--amber); background: var(--amber-soft); }
.drop input { position: absolute; width: 1px; height: 1px; opacity: 0; }
.drop:focus-within { border-color: var(--amber); }
.drop-title { font: 600 18px var(--body); }
.drop-sub { color: var(--muted); font-size: 14px; }

.chosen {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 14px 16px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface);
}
.chip { font: 500 11px var(--mono); letter-spacing: .08em; text-transform: uppercase; color: var(--amber); border: 1px solid currentColor; border-radius: 999px; padding: 2px 8px; }
.chosen-name { font-weight: 600; overflow-wrap: anywhere; min-width: 0; flex: 1; }
.chosen-size { font: 13px var(--mono); color: var(--muted); }
.clear { font: 500 13px var(--body); color: var(--muted); background: none; border: 0; cursor: pointer; text-decoration: underline; }

.options { display: grid; gap: 12px; }
.field { display: grid; gap: 6px; font-weight: 500; }
.field em { font-style: normal; color: var(--muted); font-weight: 400; }
.field input {
  font: 15px var(--body); color: var(--ink); background: var(--surface);
  border: 1px solid var(--line); border-radius: 10px; padding: 11px 12px;
}
.field input:focus { outline: none; border-color: var(--amber); }
.check { display: flex; gap: 10px; align-items: center; color: var(--muted); }
.check input { accent-color: var(--amber); width: 18px; height: 18px; }

.go {
  justify-self: start; font: 600 16px var(--body); color: #1d1a17; background: var(--amber);
  border: 0; border-radius: 10px; padding: 13px 22px; cursor: pointer;
}
.go:disabled { opacity: .45; cursor: not-allowed; }

.work { display: grid; gap: 10px; justify-items: center; }
.work canvas { width: 100%; max-width: 256px; aspect-ratio: 1; image-rendering: pixelated; border-radius: 6px; border: 6px solid var(--ink); }
.meter { width: 100%; height: 6px; background: var(--line); border-radius: 3px; overflow: hidden; }
.meter-fill { height: 100%; width: 0; background: var(--amber); transition: width .2s; }
.status { margin: 0; font: 14px var(--mono); color: var(--muted); text-align: center; }

.explain { border-top: 1px solid var(--line); padding-top: 24px; color: var(--muted); }
.explain h2 { font: 600 18px var(--display); color: var(--ink); margin: 0 0 12px; }
.explain ol { padding-left: 20px; margin: 0 0 12px; display: grid; gap: 8px; }
.explain b { color: var(--ink); }
.note { font-size: 14px; margin: 0; }
code { font: 13px var(--mono); }

.toasts { position: fixed; right: 16px; bottom: 16px; display: grid; gap: 8px; max-width: min(380px, calc(100vw - 32px)); }
.toast { background: var(--surface); border: 1px solid var(--line); border-left: 4px solid var(--ok); border-radius: 10px; padding: 12px 14px; box-shadow: 0 8px 24px rgb(0 0 0 / .15); }
.toast.bad { border-left-color: var(--bad); }

@media (max-width: 520px) {
  .sprockets { display: none; }
  .page { padding: 32px 16px 64px; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }