/* QR Studio — precision-instrument UI */

:root {
  --bg: #f4f4f2;
  --surface: #ffffff;
  --surface-2: #ececea;
  --ink: #16161a;
  --ink-2: #55555e;
  --ink-3: #8a8a92;
  --line: #dcdcd8;
  --accent: #1a56db;
  --accent-ink: #ffffff;
  --accent-hover: #1447b8;
  --danger: #b42318;
  --warn-bg: #fef3f2;
  --warn-line: #fecdca;
  --ok: #067647;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(16, 16, 20, 0.06), 0 4px 16px rgba(16, 16, 20, 0.06);
  --font: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101013;
    --surface: #1a1a20;
    --surface-2: #232329;
    --ink: #f2f2f4;
    --ink-2: #b5b5bd;
    --ink-3: #7d7d86;
    --line: #33333b;
    --accent: #6d9bff;
    --accent-ink: #0d1526;
    --accent-hover: #8ab0ff;
    --danger: #ff8a80;
    --warn-bg: #2a1715;
    --warn-line: #5c2b25;
    --ok: #5fd3a5;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 4px 16px rgba(0, 0, 0, 0.35);
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

.skip-link {
  position: absolute;
  left: 12px;
  top: -48px;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 8px 14px;
  border-radius: 6px;
  z-index: 10;
  transition: top 0.15s ease;
  text-decoration: none;
  font-weight: 600;
}
.skip-link:focus { top: 12px; }

/* ---------- Header / footer ---------- */

.site-header {
  padding: 20px 24px 0;
  max-width: 1180px;
  width: 100%;
  margin: 0 auto;
}

.brand { display: flex; align-items: center; gap: 12px; }

.brand-mark {
  width: 34px; height: 34px;
  border-radius: 8px;
  background:
    linear-gradient(var(--ink), var(--ink)) 6px 6px / 8px 8px no-repeat,
    linear-gradient(var(--ink), var(--ink)) 20px 6px / 8px 8px no-repeat,
    linear-gradient(var(--ink), var(--ink)) 6px 20px / 8px 8px no-repeat,
    linear-gradient(var(--ink), var(--ink)) 20px 20px / 8px 8px no-repeat,
    var(--surface);
  border: 1px solid var(--line);
  flex: none;
}

.brand-name {
  margin: 0;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
}

.brand-tag {
  margin: 0;
  font-size: 0.8rem;
  color: var(--ink-3);
}

.site-footer {
  padding: 18px 24px 28px;
  text-align: center;
  color: var(--ink-3);
  font-size: 0.8rem;
}

/* ---------- Layout ---------- */

.layout {
  flex: 1;
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 20px 24px;
  display: grid;
  grid-template-columns: minmax(340px, 460px) 1fr;
  gap: 20px;
  align-items: start;
}

.pane-controls { display: flex; flex-direction: column; gap: 16px; }

.pane-preview {
  position: sticky;
  top: 20px;
}

/* ---------- Cards ---------- */

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
}

.card-title {
  margin: 0 0 14px;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-3);
}

/* ---------- Tabs ---------- */

.tabs {
  display: flex;
  gap: 4px;
  background: var(--surface-2);
  padding: 4px;
  border-radius: 8px;
  margin-bottom: 16px;
}

.tab {
  flex: 1;
  border: 0;
  background: transparent;
  color: var(--ink-2);
  font: inherit;
  font-weight: 600;
  font-size: 0.9rem;
  padding: 9px 12px;
  border-radius: 6px;
  cursor: pointer;
  min-height: 44px;
  transition: background 0.12s ease, color 0.12s ease;
}

.tab:hover { color: var(--ink); }

.tab[aria-selected="true"] {
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 1px 3px rgba(16, 16, 20, 0.12);
}

/* ---------- Fields ---------- */

.mode-fields { display: flex; flex-direction: column; gap: 14px; }

.field { display: flex; flex-direction: column; gap: 6px; min-width: 0; }

.field-row {
  display: flex;
  gap: 12px;
  align-items: flex-end;
  flex-wrap: wrap;
}

.field-row .field { flex: 1; min-width: 120px; }

.field-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--ink-2);
}

.label-hint { font-weight: 400; color: var(--ink-3); }

.field-input {
  font: inherit;
  color: var(--ink);
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  min-height: 44px;
  width: 100%;
  transition: border-color 0.12s ease, box-shadow 0.12s ease;
}

textarea.field-input { resize: vertical; line-height: 1.45; }

.field-input:focus-visible {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent);
}

.field-input[aria-invalid="true"] {
  border-color: var(--danger);
}

.field-error {
  margin: 0;
  font-size: 0.82rem;
  color: var(--danger);
}

/* ---------- Color + range fields ---------- */

.color-field {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px 10px;
  min-height: 44px;
}

.color-field input[type="color"] {
  width: 34px; height: 34px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: none;
  cursor: pointer;
}

.color-hex {
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--ink-2);
}

.range-field { display: flex; align-items: center; gap: 12px; min-height: 44px; }

.range-field input[type="range"] { flex: 1; accent-color: var(--accent); min-height: 32px; }

.range-value {
  font-family: var(--mono);
  font-size: 0.85rem;
  min-width: 2ch;
  text-align: right;
  color: var(--ink-2);
}

.contrast-warning {
  margin: 4px 0 0;
  padding: 10px 12px;
  background: var(--warn-bg);
  border: 1px solid var(--warn-line);
  border-radius: 8px;
  color: var(--danger);
  font-size: 0.84rem;
}

/* ---------- Preview ---------- */

.card-preview {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.preview-box {
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 8px;
  min-height: 300px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  overflow: hidden;
}

#preview-canvas {
  image-rendering: pixelated;
  max-width: 100%;
  height: auto;
  border-radius: 2px;
}

#preview-canvas.pulse { animation: pulse 0.18s ease-out; }

@keyframes pulse {
  from { opacity: 0.55; transform: scale(0.985); }
  to { opacity: 1; transform: scale(1); }
}

@media (prefers-reduced-motion: reduce) {
  #preview-canvas.pulse { animation: none; }
  .tab, .field-input, .btn { transition: none; }
}

.preview-message {
  margin: 0;
  max-width: 40ch;
  text-align: center;
  color: var(--ink-2);
  font-size: 0.95rem;
}

/* ---------- Capacity ---------- */

.capacity { display: flex; flex-direction: column; gap: 6px; }

.capacity-bar {
  height: 6px;
  border-radius: 3px;
  background: var(--surface-2);
  overflow: hidden;
}

.capacity-fill {
  height: 100%;
  width: 0;
  background: var(--ok);
  border-radius: 3px;
  transition: width 0.2s ease;
}

.capacity-fill.is-hot { background: var(--danger); }

.capacity-text {
  margin: 0;
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--ink-3);
}

/* ---------- Actions ---------- */

.actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  font: inherit;
  font-weight: 650;
  font-size: 0.95rem;
  border-radius: 8px;
  padding: 12px 20px;
  min-height: 48px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background 0.12s ease, border-color 0.12s ease, opacity 0.12s ease;
}

.btn:disabled { opacity: 0.45; cursor: not-allowed; }

.btn-primary {
  flex: 1;
  background: var(--accent);
  color: var(--accent-ink);
}

.btn-primary:not(:disabled):hover { background: var(--accent-hover); }

.btn-secondary {
  background: transparent;
  color: var(--ink);
  border-color: var(--line);
}

.btn-secondary:not(:disabled):hover { border-color: var(--ink-3); }

.btn-ghost {
  background: transparent;
  color: var(--ink-2);
  border-color: var(--line);
  padding: 8px 14px;
  min-height: 44px;
  font-size: 0.85rem;
}

.btn-ghost:hover { color: var(--ink); border-color: var(--ink-3); }

.btn.is-flashed { border-color: var(--ok); }

.btn:focus-visible, .tab:focus-visible, input[type="color"]:focus-visible,
input[type="range"]:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ---------- Responsive ---------- */

@media (max-width: 880px) {
  .layout {
    grid-template-columns: 1fr;
    padding: 14px 16px;
  }
  .pane-preview { position: static; order: -1; }
  .site-header { padding: 16px 16px 0; }
  .preview-box { min-height: 240px; padding: 16px; }
}