:root {
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --primary: #6366f1;
  --primary-hover: #4f46e5;
  --shadow: 0 8px 24px rgba(15, 23, 42, 0.08);
}

[data-theme="dark"] {
  --bg: #0f172a;
  --surface: #1e293b;
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --border: #334155;
  --primary: #818cf8;
  --primary-hover: #a5b4fc;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'Cairo', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background 0.3s, color 0.3s;
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 1.25rem; }

/* Header */
.app-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky; top: 0; z-index: 10;
  backdrop-filter: blur(8px);
}
.app-header .container { display: flex; align-items: center; gap: 1rem; }
.back-link {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 700;
  font-size: 0.9rem;
  padding: 0.5rem 0.75rem;
  border-radius: 0.5rem;
  transition: background 0.2s;
}
.back-link:hover { background: var(--bg); }
.brand { display: flex; align-items: center; gap: 0.75rem; flex: 1; }
.logo { font-size: 2rem; }
.brand h1 { font-size: 1.4rem; font-weight: 900; }
.brand p { font-size: 0.8rem; color: var(--text-muted); font-weight: 600; }
.theme-btn {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 9999px;
  width: 44px; height: 44px;
  font-size: 1.2rem;
  cursor: pointer;
  transition: transform 0.2s, background 0.2s;
}
.theme-btn:hover { transform: scale(1.1); }

/* Main */
.main { flex: 1; padding: 2rem 1.25rem; display: flex; flex-direction: column; gap: 1.5rem; }

.controls { display: flex; flex-wrap: wrap; gap: 0.75rem; justify-content: center; }
.btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: 0.75rem;
  font-family: inherit;
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.15s, background 0.2s, box-shadow 0.2s;
}
.btn.primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
}
.btn.primary:hover { background: var(--primary-hover); transform: translateY(-2px); }
.btn.ghost {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border);
}
.btn.ghost:hover { background: var(--bg); transform: translateY(-2px); }
.btn kbd {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  background: rgba(255,255,255,0.25);
  padding: 0.15rem 0.4rem;
  border-radius: 0.25rem;
}

/* Palette */
.palette {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.75rem;
  min-height: 60vh;
  border-radius: 1rem;
  overflow: hidden;
  box-shadow: var(--shadow);
}
@media (max-width: 768px) {
  .palette { grid-template-columns: 1fr; min-height: auto; }
  .swatch { min-height: 110px; }
}
.swatch {
  position: relative;
  cursor: pointer;
  border-radius: 0.75rem;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  padding: 1rem;
  transition: transform 0.25s ease;
  overflow: hidden;
}
.swatch:hover { transform: scale(1.02); }
.swatch .hex {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  font-size: 1rem;
  padding: 0.4rem 0.65rem;
  border-radius: 0.5rem;
  background: rgba(255,255,255,0.85);
  color: #0f172a;
  letter-spacing: 0.5px;
  user-select: all;
}
.swatch .lock-btn {
  background: rgba(255,255,255,0.85);
  border: none;
  width: 38px; height: 38px;
  border-radius: 50%;
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.15s, background 0.2s;
}
.swatch .lock-btn:hover { transform: scale(1.15); }
.swatch.locked .lock-btn { background: #fbbf24; }
.swatch.dark-text .hex,
.swatch.dark-text .lock-btn { background: rgba(15,23,42,0.85); color: #fff; }

.hint {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--text);
  color: var(--bg);
  padding: 0.75rem 1.5rem;
  border-radius: 9999px;
  font-weight: 700;
  font-size: 0.9rem;
  box-shadow: var(--shadow);
  opacity: 0;
  transition: opacity 0.3s, transform 0.3s;
  pointer-events: none;
  z-index: 100;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* Footer */
.app-footer {
  border-top: 1px solid var(--border);
  padding: 1.25rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}
.app-footer a { color: var(--primary); text-decoration: none; font-weight: 700; }
.app-footer a:hover { text-decoration: underline; }