:root {
  font-family: system-ui, Avenir, Helvetica, Arial, sans-serif;
  line-height: 1.5;
  font-weight: 400;

  color-scheme: light dark;
  color: rgba(255, 255, 255, 0.87);
  background-color: #242424;

  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;

  /* --- Glassmorphism Design System (from Nonograms) --- */
  --bg-gradient: radial-gradient(circle at center, #444 0%, #000000 100%);
  --glass-bg: rgba(255, 255, 255, 0.1);
  --glass-border: rgba(255, 255, 255, 0.2);
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  --text-color: #ffffff;
  --text-strong: #ffffff;
  --text-secondary: rgba(255, 255, 255, 0.85);
  --text-muted: rgba(255, 255, 255, 0.7);
  --accent-cyan: #00f2fe;
  --accent-purple: #4facfe;
  --primary-accent: #00f2fe;
  --title-glow: rgba(0, 255, 255, 0.2);
  --toggle-bg: rgba(255, 255, 255, 0.08);
  --toggle-border: rgba(255, 255, 255, 0.2);
  --toggle-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
  --toggle-btn-border: rgba(255, 255, 255, 0.2);
  --toggle-hover-border: #ffffff;
  --toggle-active-shadow: 0 0 10px rgba(0, 242, 255, 0.3);
  --panel-bg: rgba(255, 255, 255, 0.1);
  --panel-border: rgba(255, 255, 255, 0.1);
  --panel-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
  --button-bg: rgba(255, 255, 255, 0.1);
  --button-border: rgba(255, 255, 255, 0.2);
  --button-text: #ffffff;
  --button-hover-bg: rgba(255, 255, 255, 0.25);
  --button-hover-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
  --button-active-shadow: 0 0 20px rgba(79, 172, 254, 0.4);
  --cube-edge-color: #333333;
  --title-gradient: linear-gradient(45deg, #00f2fe, #4facfe);
}

:root[data-theme="light"] {
  --bg-gradient: radial-gradient(circle at center, #ffffff 0%, #cccccc 100%);
  --glass-bg: rgba(255, 255, 255, 0.75);
  --glass-border: rgba(15, 23, 42, 0.12);
  --glass-shadow: 0 8px 32px 0 rgba(15, 23, 42, 0.12);
  --text-color: #0f172a;
  --text-strong: #0f172a;
  --text-secondary: rgba(15, 23, 42, 0.7);
  --text-muted: rgba(15, 23, 42, 0.6);
  --accent-cyan: #0ea5e9;
  --accent-purple: #6366f1;
  --primary-accent: #0ea5e9;
  --title-glow: rgba(14, 165, 233, 0.35);
  --toggle-bg: rgba(255, 255, 255, 0.85);
  --toggle-border: rgba(15, 23, 42, 0.12);
  --toggle-shadow: 0 8px 20px rgba(15, 23, 42, 0.12);
  --toggle-btn-border: rgba(15, 23, 42, 0.18);
  --toggle-hover-border: rgba(15, 23, 42, 0.5);
  --toggle-active-shadow: 0 0 12px rgba(14, 165, 233, 0.25);
  --panel-bg: rgba(255, 255, 255, 0.7);
  --panel-border: rgba(15, 23, 42, 0.12);
  --panel-shadow: 0 12px 24px rgba(15, 23, 42, 0.12);
  --button-bg: rgba(255, 255, 255, 0.85);
  --button-border: rgba(15, 23, 42, 0.16);
  --button-text: #0f172a;
  --button-hover-bg: rgba(255, 255, 255, 1);
  --button-hover-shadow: 0 6px 18px rgba(15, 23, 42, 0.18);
  --button-active-shadow: 0 0 18px rgba(14, 165, 233, 0.25);
  --cube-edge-color: #000000;
  --title-gradient: linear-gradient(45deg, #0ea5e9, #6366f1);
}

a {
  font-weight: 500;
  color: #646cff;
  text-decoration: inherit;
}
a:hover {
  color: #535bf2;
}

body {
  margin: 0;
  display: flex;
  min-width: 320px;
  height: 100vh;
  flex-direction: column;
  background: var(--bg-gradient);
  background-attachment: fixed;
  color: var(--text-color);
  overflow: hidden;
}

h1 {
  font-size: 3.2em;
  line-height: 1.1;
}

button {
  border-radius: 8px;
  border: 1px solid transparent;
  padding: 0.6em 1.2em;
  font-size: 1em;
  font-weight: 500;
  font-family: inherit;
  background-color: #1a1a1a;
  cursor: pointer;
  transition: border-color 0.25s;
}
button:hover {
  border-color: #646cff;
}
button:focus,
button:focus-visible {
  outline: 4px auto -webkit-focus-ring-color;
}

.card {
  padding: 2em;
}

#app {
  width: 100%;
  height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* Glassmorphism utility class */
.glass-panel {
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-radius: 16px;
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow);
}

/* Button Styles */
button.btn-neon {
  background: var(--button-bg);
  border: 1px solid var(--button-border);
  color: var(--button-text);
  padding: 10px 20px;
  font-size: 0.95rem;
  border-radius: 30px;
  cursor: pointer;
  transition: all 0.3s ease;
  backdrop-filter: blur(4px);
  font-weight: 500;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  outline: none;
}

button.btn-neon:hover {
  background: var(--button-hover-bg);
  transform: translateY(-2px);
  box-shadow: var(--button-hover-shadow);
  border-color: var(--toggle-hover-border);
}

button.btn-neon.active {
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-purple));
  border-color: transparent;
  box-shadow: var(--button-active-shadow);
  font-weight: 700;
  color: #fff;
}

button.btn-neon.icon-only {
  padding: 10px;
  border-radius: 50%;
  width: 40px;
  height: 40px;
}

@media (prefers-color-scheme: light) {
  :root {
    color: #213547;
    background-color: #ffffff;
  }
  a:hover {
    color: #747bff;
  }
  button {
    background-color: #f9f9f9;
  }
}