/* Fox Hunt flasher.
   Plain CSS, no framework: the page has to work offline in a field from a
   service-worker cache, so every byte is local. */

:root {
  --bg: #fbfaf7;
  --fg: #1c1b19;
  --muted: #5d5a54;
  --line: #ddd8cf;
  --card: #ffffff;
  --accent: #a8420a;
  --accent-fg: #ffffff;
  --ok-bg: #e6f4e6;
  --ok-fg: #1c5c22;
  --bad-bg: #fbe6e4;
  --bad-fg: #8c2016;
  --warn-bg: #fdf3d8;
  --warn-fg: #6b4c05;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #161513;
    --fg: #ece9e3;
    --muted: #a49f96;
    --line: #34312c;
    --card: #201e1b;
    --accent: #e2803f;
    --accent-fg: #1a1512;
    --ok-bg: #16301a;
    --ok-fg: #8fd398;
    --bad-bg: #3a1a17;
    --bad-fg: #f0a49b;
    --warn-bg: #362c12;
    --warn-fg: #e8c877;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0 auto;
  padding: 1.5rem 1.25rem 4rem;
  max-width: 46rem;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", sans-serif;
}

h1 { font-size: 1.6rem; margin: 0 0 .25rem; }
h2 { font-size: 1.15rem; margin: 2.25rem 0 .5rem; }
.lead { color: var(--muted); margin-top: 0; }

section { border-top: 1px solid var(--line); padding-top: .25rem; }
header { padding-bottom: .5rem; }

button {
  font: inherit;
  font-weight: 600;
  padding: .6rem 1rem;
  border: 1px solid var(--line);
  border-radius: .4rem;
  background: var(--card);
  color: var(--fg);
  cursor: pointer;
}
button:hover:not(:disabled) { border-color: var(--accent); }
button:disabled { opacity: .45; cursor: not-allowed; }
button.primary { background: var(--accent); color: var(--accent-fg); border-color: transparent; }

.row { display: flex; flex-wrap: wrap; gap: .6rem; align-items: center; }

input[type=number] {
  font: inherit;
  width: 5.5rem;
  padding: .5rem;
  border: 1px solid var(--line);
  border-radius: .4rem;
  background: var(--card);
  color: var(--fg);
}
label { font-weight: 600; }

.note { color: var(--muted); font-size: .9rem; }

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: .5rem;
  padding: .9rem 1rem;
  margin: .75rem 0;
}

.banner { border-radius: .5rem; padding: .8rem 1rem; margin: .75rem 0; }
.banner.bad  { background: var(--bad-bg);  color: var(--bad-fg); }
.banner.ok   { background: var(--ok-bg);   color: var(--ok-fg); }
.banner.warn { background: var(--warn-bg); color: var(--warn-fg); }

.bar { height: .55rem; background: var(--line); border-radius: .3rem; overflow: hidden; }
.bar > div { height: 100%; width: 0; background: var(--accent); transition: width .2s; }

table { border-collapse: collapse; width: 100%; margin: .5rem 0; }
th, td { text-align: left; padding: .4rem .6rem; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-size: .85rem; text-transform: uppercase; letter-spacing: .03em; color: var(--muted); }

code, .mono { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .9em; }

dl.kv { display: grid; grid-template-columns: max-content 1fr; gap: .2rem .9rem; margin: 0; }
dl.kv dt { color: var(--muted); }
dl.kv dd { margin: 0; }

details { margin: .5rem 0; }
summary { cursor: pointer; font-weight: 600; padding: .35rem 0; }

footer { border-top: 1px solid var(--line); margin-top: 2.5rem; padding-top: 1rem; color: var(--muted); font-size: .85rem; }

.stream { max-height: 14rem; overflow: auto; font-family: ui-monospace, Menlo, monospace; font-size: .82rem; white-space: pre-wrap; }

@media (max-width: 30rem) {
  body { padding: 1rem .8rem 3rem; }
  button { width: 100%; }
  .row { display: block; }
  .row > * { margin-bottom: .5rem; }
}

/* Every action has to show something happening within a frame or two. The slow
   steps here are the device chooser, reading a board over the REPL, and a 23
   second full flash -- all long enough that a page which simply greys a button
   looks broken. */
.status {
  display: flex;
  align-items: center;
  gap: .6rem;
  margin: .75rem 0;
  color: var(--muted);
}

.spinner {
  flex: none;
  width: 1rem;
  height: 1rem;
  border: 2px solid var(--line);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin .8s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

@media (prefers-reduced-motion: reduce) {
  .spinner { animation: none; }
}

.status.done .spinner { border: 2px solid var(--ok-fg); animation: none; }
.bad-text { color: var(--bad-fg); }

/* The zone diagram in the introduction. Someone who has never seen a fox hunt
   needs to grasp "three nested signals, not one" before anything else on this
   page makes sense, and a picture does that faster than a paragraph. */
.diagram {
  display: block;
  width: 100%;
  max-width: 28rem;
  height: auto;
  margin: 1.2rem auto;
}
.diagram circle { fill: none; stroke: var(--accent); }
.diagram .z1 { stroke-opacity: .35; stroke-dasharray: 4 4; }
.diagram .z2 { stroke-opacity: .6; stroke-dasharray: 4 4; }
.diagram .z3 { stroke-opacity: .95; }
.diagram .lbl { font: 11px system-ui, sans-serif; fill: var(--muted); }
.diagram .fox, .diagram .hound { font-size: 22px; }
/* A plain dashed line, deliberately with no arrowhead: an arrow would imply the
   Hound knows which way to go, which is exactly what it cannot do. */
.diagram .sight {
  stroke: var(--muted);
  stroke-width: 1.2;
  stroke-dasharray: 3 3;
  fill: none;
}

h3 { font-size: 1rem; margin: 1.4rem 0 .3rem; }

.warn-text { color: var(--accent); }