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

body {
  font-family: "Segoe UI", system-ui, sans-serif;
  background: #0f0f1a;
  color: #e0e0e0;
  min-height: 100vh;
}

header {
  text-align: center;
  padding: 3rem 1rem 2rem;
}

h1 {
  font-size: 2.5rem;
  font-weight: 600;
  background: linear-gradient(135deg, #fff, #a0a0ff);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.subtitle {
  color: #888;
  margin-top: 0.5rem;
}

main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem 3rem;
}

.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
  justify-content: center;
}

.tag-filter {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #ccc;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.9rem;
  transition: all 0.2s;
}

.tag-filter:hover {
  background: rgba(255, 255, 255, 0.1);
}

.tag-filter.active {
  background: rgba(100, 100, 200, 0.3);
  border-color: rgba(100, 100, 200, 0.5);
  color: #fff;
}

.simulations-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
}

.simulation-card {
  background: rgba(20, 20, 35, 0.8);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 12px;
  overflow: hidden;
  transition: transform 0.2s, box-shadow 0.2s;
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  display: block;
}

.simulation-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
}

.simulation-card .thumbnail {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #1a1a2e;
  object-fit: cover;
}

.simulation-card .content {
  padding: 1.25rem;
}

.simulation-card h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.simulation-card p {
  font-size: 0.9rem;
  color: #999;
  line-height: 1.5;
  margin-bottom: 1rem;
}

.simulation-card .tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag {
  font-size: 0.75rem;
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.difficulty {
  font-size: 0.75rem;
  color: #666;
  margin-top: 0.75rem;
  text-transform: capitalize;
}

@media (max-width: 640px) {
  h1 {
    font-size: 1.75rem;
  }

  .simulations-grid {
    grid-template-columns: 1fr;
  }
}