:root {
  --bg: #f4f4f4;
  --fg: #222;
  --card-bg: #fff;
  --card-fg: #000;
  --primary: #0066cc;
  --accent: #e0e0e0;
  --shadow: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
  --bg: #121212;
  --fg: #eee;
  --card-bg: #1e1e1e;
  --card-fg: #fff;
  --primary: #3399ff;
  --accent: #333;
  --shadow: rgba(0, 0, 0, 0.3);
}

body {
  margin: 0;
  padding: 0;
  font-family: "Segoe UI", sans-serif;
  background-color: var(--bg);
  color: var(--fg);
  transition: background 0.3s, color 0.3s;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 2em;
}

header {
  text-align: center;
  margin-bottom: 2em;
}

.logo {
  max-width: 80px;
  margin-bottom: 1em;
}

h1 {
  margin: 0.2em 0;
  font-size: 1.8em;
}

.description {
  font-size: 0.95em;
  line-height: 1.6;
  margin-bottom: 1.5em;
}

button#toggleTheme {
  padding: 0.5em 1em;
  font-size: 0.9em;
  border: none;
  background: var(--accent);
  color: var(--fg);
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.3s;
}

button#toggleTheme:hover {
  background: var(--primary);
  color: white;
}

.card-container {
  display: flex;
  flex-direction: column;
  gap: 1em;
  align-items: stretch;
}

.card {
  background-color: var(--card-bg);
  color: var(--card-fg);
  padding: 1em;
  border-radius: 12px;
  text-decoration: none;
  box-shadow: 0 2px 6px var(--shadow);
  transition: transform 0.2s, background 0.2s;
  font-size: 1.1em;
  text-align: center;
}

.card:hover {
  background-color: var(--primary);
  color: white;
  transform: translateY(-2px);
}

footer {
  text-align: center;
  margin-top: 3em;
  font-size: 0.9em;
  color: var(--fg);
  opacity: 0.7;
}