:root {
  --primary: #4a6fa5;
  --primary-dark: #33527e;
  --bg: #f8f9fa;
  --card: #fff;
  --text: #333;
  --muted: #6b7280;
  --line: #dfe3e8;
  --danger: #c62828;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
}

a {
  color: var(--primary);
  text-decoration: none;
}

button,
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  border: 1px solid var(--primary);
  border-radius: 6px;
  padding: 8px 16px;
  background: var(--primary);
  color: #fff;
  font: inherit;
  cursor: pointer;
  gap: 6px;
}

button.secondary,
.button.secondary {
  background: #fff;
  color: var(--primary);
}

button:disabled {
  opacity: .55;
  cursor: not-allowed;
}

.site-header {
  background: #fff;
  border-bottom: 1px solid var(--line);
}

.site-header-inner {
  max-width: 800px;
  margin: 0 auto;
  padding: 12px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.brand {
  color: var(--text);
  font-weight: 700;
}

.nav {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  font-size: 14px;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 18px 16px 36px;
}

.ad-slot {
  min-height: 90px;
  border: 1px dashed #c8cdd3;
  background: #eee;
  color: #777;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 0 18px;
}

.ad-bottom {
  margin-top: 18px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
}

.card,
.panel {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
}

.card h2,
.panel h1,
.panel h2 {
  margin: 0 0 8px;
}

.muted {
  color: var(--muted);
}

.tabs,
.toolbar,
.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 14px;
}

.tab {
  background: #fff;
  color: var(--primary);
}

.tab.active,
.mode.active {
  background: var(--primary);
  color: #fff;
}

.progress {
  height: 12px;
  background: #e5e7eb;
  border-radius: 999px;
  overflow: hidden;
  margin: 8px 0;
}

.progress-bar {
  height: 100%;
  width: 0;
  background: var(--primary);
  transition: width .35s ease;
}

.puzzle-list {
  display: grid;
  gap: 10px;
}

.puzzle-card {
  display: block;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  color: var(--text);
}

.puzzle-card:hover {
  border-color: var(--primary);
}

.badge {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  border-radius: 999px;
  padding: 2px 10px;
  background: #eef2ff;
  color: var(--primary-dark);
  font-size: 13px;
}

.canvas-wrap {
  width: 100%;
  overflow-x: auto;
  text-align: center;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px;
}

canvas {
  max-width: 100%;
  height: auto;
  touch-action: none;
}

.overlay {
  position: fixed;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, .35);
  z-index: 10;
}

.overlay.show {
  display: flex;
}

.overlay-box {
  background: #fff;
  border-radius: 8px;
  padding: 24px 32px;
  font-size: 24px;
  font-weight: 700;
}

.form {
  display: grid;
  gap: 12px;
}

input {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 8px 10px;
  font: inherit;
}

.error {
  color: var(--danger);
}

@media (max-width: 560px) {
  .site-header-inner,
  .nav {
    align-items: flex-start;
  }

  button,
  .button {
    padding: 8px 12px;
  }
}