/* --- Theming --- */

:root {
  color-scheme: light dark;

  --bg: #ffffff;
  --text: #1a1a1a;
  --text-muted: #555;
  --cell-on: #1a1a1a;
  --cell-off: #f0f0f0;
  --grid-border: #ccc;
  --control-bg: #f5f5f5;
  --control-border: #ccc;
  --focus-ring: #2563eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1a1a;
    --text: #e0e0e0;
    --text-muted: #999;
    --cell-on: #1a1a1a;
    --cell-off: #f0f0f0;
    --grid-border: #444;
    --control-bg: #2a2a2a;
    --control-border: #444;
    --focus-ring: #60a5fa;
  }
}

/* --- Base --- */

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 16px;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: 1rem;
  line-height: 1.6;
}

/* --- Layout --- */

main {
  max-width: 1060px;
  margin: 0 auto;
}

/* --- Typography --- */

h1 {
  font-size: 1.5rem;
  margin: 32px 0 8px;
  text-align: center;
}

h2 {
  font-size: 1.25rem;
  margin: 8px 0 32px;
  text-align: center;
}

a {
  color: var(--focus-ring);
}

blockquote {
  margin: 16px 0;
  padding: 0 0 0 16px;
  border-left: 3px solid var(--grid-border);
  color: var(--text-muted);
}

blockquote cite {
  display: block;
  margin-top: 8px;
  font-style: italic;
}

/* --- Grid --- */

.grid {
  display: grid;
  grid-template-columns: repeat(var(--cols), 20px);
  gap: 1px;
  background: var(--grid-border);
  border: 1px solid var(--grid-border);
  width: fit-content;
  margin: 0 auto;
  overflow-x: auto;
}

.cell {
  width: 20px;
  height: 20px;
  background: var(--cell-off);
}

.cell.on {
  background: var(--cell-on);
}

/* --- Controls --- */

#controls {
  margin: 16px auto 0;
  max-width: 600px;
}

.control-group {
  display: flex;
  align-items: center;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.field {
  display: flex;
  align-items: center;
  gap: 2px;
}

.frame-nav {
  justify-content: center;
  gap: 8px;
}

button,
input,
select,
textarea {
  font-family: inherit;
  font-size: 0.875rem;
  padding: 4px 8px;
  background: var(--control-bg);
  color: var(--text);
  border: 1px solid var(--control-border);
  border-radius: 4px;
}

button {
  cursor: pointer;
}

button:hover {
  filter: brightness(0.95);
}

input[type="number"] {
  width: 60px;
}

input[type="text"],
textarea {
  width: 100%;
}

textarea {
  resize: vertical;
}

/* Focus: visible for keyboard, invisible for mouse */
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--focus-ring);
  outline-offset: 1px;
}

/* --- About section --- */

#about {
  max-width: 640px;
  margin: 32px auto 0;
}