:root {
  --bg-color: #f9fafb;
  --text-color: #111;
  --card-bg: #ffffff;
  --card-hover: #f3f4f6;
}

body.dark {
  --bg-color: #0e1624;
  --text-color: #e5e7eb;
  --card-bg: #1e293b;
  --card-hover: #334155;
}

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

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 40px 20px;
  text-align: center;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
}

.logo {
  font-size: 1.8rem;
  font-weight: bold;
}

.theme-toggle {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-color);
  transition: color 0.3s;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 15px;
}

.card {
  background: var(--card-bg);
  padding: 20px;
  border-radius: 14px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  transition: background 0.3s, transform 0.2s;
}

.card:hover {
  background: var(--card-hover);
  transform: translateY(-3px);
}

.card img {
  width: 100%;
  border-radius: 12px;
  margin-top: 10px;
}

.card.wide {
  grid-column: span 2;
}

footer {
  margin-top: 50px;
  font-size: 0.9rem;
  opacity: 0.7;
}

.card-link {
  text-decoration: none;
  color: inherit;
}

.card-link .card {
  cursor: pointer;
}

.card-link .card:hover {
  background: var(--card-hover);
  transform: translateY(-3px);
}