:root {
  --bg: #f4f4f4;
  --surface: #ffffff;
  --fg: #1a1a1a;
  --muted: #5f5f5f;
  --border: #d6d6d6;
  --accent: #1a1a1a;
  --accent-fg: #ffffff;
  --accent-soft: #e6e6e6;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.06), 0 4px 16px rgb(0 0 0 / 0.06);
  --page-shadow: drop-shadow(0 0 1px rgb(0 0 0 / 0.35)) drop-shadow(0 4px 10px rgb(0 0 0 / 0.08));
  --radius: 10px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #161616;
    --surface: #222222;
    --fg: #ececec;
    --muted: #a3a3a3;
    --border: #3a3a3a;
    --accent: #ececec;
    --accent-fg: #161616;
    --accent-soft: #333333;
    --shadow: 0 1px 2px rgb(0 0 0 / 0.4), 0 4px 16px rgb(0 0 0 / 0.3);
    --page-shadow: drop-shadow(0 0 1px rgb(0 0 0 / 0.8)) drop-shadow(0 4px 10px rgb(0 0 0 / 0.4));
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #161616;
  --surface: #222222;
  --fg: #ececec;
  --muted: #a3a3a3;
  --border: #3a3a3a;
  --accent: #ececec;
  --accent-fg: #161616;
  --accent-soft: #333333;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.4), 0 4px 16px rgb(0 0 0 / 0.3);
  --page-shadow: drop-shadow(0 0 1px rgb(0 0 0 / 0.8)) drop-shadow(0 4px 10px rgb(0 0 0 / 0.4));
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

.topbar {
  max-width: 960px;
  margin: 0 auto;
  padding: 12px 16px 0;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--fg);
  font-weight: 700;
  font-size: 18px;
  text-decoration: none;
}

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 8px 16px 32px;
}

h1 { font-size: clamp(24px, 4vw, 34px); line-height: 1.2; margin: 16px 0 8px; text-wrap: balance; }
h2 { font-size: 18px; margin: 0 0 8px; }
p { margin: 0 0 12px; }

.howto { margin: 0 0 24px; padding-left: 22px; color: var(--muted); }
.howto li { margin: 2px 0; }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr));
  gap: 16px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}

.row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin: 8px 0; }
.row.between { justify-content: space-between; }
.row.end { justify-content: flex-end; margin-top: 16px; }

button, .button {
  appearance: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 40px;
  padding: 8px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--fg);
  font: inherit;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  user-select: none;
}
button:hover, .button:hover { border-color: var(--muted); }
button:disabled { opacity: 0.4; cursor: default; }
button:focus-visible, .button:focus-visible, textarea:focus-visible, input:focus-visible, summary:focus-visible {
  outline: 2px solid var(--fg);
  outline-offset: 2px;
}
.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.primary:hover { border-color: var(--accent); opacity: 0.88; }
button[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--fg); }

textarea, input[type="text"] {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--fg);
  font: inherit;
}
textarea { resize: vertical; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 13px; word-break: break-all; }
input[type="range"] { accent-color: var(--fg); }

.fine { font-size: 13px; color: var(--muted); margin: 8px 0 0; }
.hint { color: var(--muted); margin: 12px auto; max-width: 64ch; text-align: center; text-wrap: balance; }
.error, .warning {
  border-left: 3px solid var(--fg);
  border-radius: 4px;
  background: var(--accent-soft);
  color: var(--fg);
  padding: 10px 12px;
  font-size: 14px;
}
.error::before, .warning::before { content: "⚠ "; font-weight: 700; }
.warning { margin: 8px 0; }

.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap;
}

/* drawing */
.toolbar { display: flex; flex-wrap: wrap; gap: 8px 16px; margin-bottom: 12px; align-items: center; justify-content: center; }
.group { display: flex; gap: 4px; align-items: center; }
.sizes button { width: 40px; padding: 0; }
.sizes i { display: block; width: var(--d); height: var(--d); border-radius: 50%; background: currentColor; }
.strip-control { gap: 8px; font-size: 14px; font-weight: 500; }
.strip-control input { width: 120px; }
.strip-control output { min-width: 40px; color: var(--muted); font-variant-numeric: tabular-nums; }

.stage { display: flex; justify-content: center; }
canvas.pixels {
  display: block;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  filter: var(--page-shadow);
}
canvas.drawing { touch-action: none; cursor: crosshair; }

/* The row under the canvas is as wide as the canvas (--stage-w is set by script), but not cramped. */
.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 12px;
  align-items: center;
  justify-content: flex-end;
  width: min(100%, max(var(--stage-w, 100%), 440px));
  margin: 12px auto 0;
}
.actions.wrap { justify-content: center; }
.status { display: flex; flex-direction: column; flex: 1 1 260px; min-width: 0; }
.note { font-size: 13px; font-weight: 600; }
.note::before { content: "⚠ "; }
.meter { font-size: 13px; color: var(--muted); font-variant-numeric: tabular-nums; }
.meter > span { display: block; }
.meter .part { white-space: nowrap; }
.meter[data-level="warn"], .meter > [data-level="warn"] { color: var(--fg); font-weight: 600; }
.meter[data-level="danger"], .meter > [data-level="danger"] { color: var(--fg); font-weight: 700; text-decoration: underline wavy; }

/* unfolding: the folded-away part swings out from behind the page, around the fold */
.page { position: relative; perspective: 1000px; }
.flap {
  position: absolute;
  top: 0;
  height: 100%;
  backface-visibility: hidden;
  transition: transform 1.2s cubic-bezier(0.3, 0.6, 0.25, 1);
}
.flap canvas { display: block; width: 100%; height: 100%; image-rendering: pixelated; image-rendering: crisp-edges; }
.flap::after {
  content: "";
  position: absolute;
  inset: 0;
  background: rgb(0 0 0 / 0.45);
  transition: opacity 1.2s ease-in;
}
.flap.left { transform-origin: 100% 50%; transform: rotateY(-180deg); }
.flap.right { transform-origin: 0 50%; transform: rotateY(180deg); }
.flap.open { transform: rotateY(0deg); }
.flap.open::after { opacity: 0; }

/* dialogs */
dialog {
  width: min(600px, calc(100vw - 24px));
  max-height: calc(100vh - 24px);
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--surface);
  color: var(--fg);
  box-shadow: 0 10px 40px rgb(0 0 0 / 0.25);
}
dialog::backdrop { background: rgb(0 0 0 / 0.45); }
.dialog { padding: 18px; }
.dialog.small { max-width: 420px; }
#confirm { width: min(420px, calc(100vw - 24px)); }

.send-grid { display: grid; grid-template-columns: auto 1fr; gap: 16px; align-items: start; margin-bottom: 12px; }
@media (max-width: 560px) { .send-grid { grid-template-columns: 1fr; } }
.preview { margin: 0; display: grid; justify-items: center; gap: 6px; }
.preview figcaption { font-size: 13px; color: var(--muted); }
.settings { display: grid; gap: 14px; }
.settings label, .label { display: grid; gap: 4px; font-size: 14px; font-weight: 500; }
.range { display: flex; gap: 8px; align-items: center; }
.range input { flex: 1; }
.range output { min-width: 48px; font-variant-numeric: tabular-nums; color: var(--muted); }
.more { margin-top: 8px; }
.more summary { cursor: pointer; font-weight: 500; padding: 4px 0; }