:root {
  --bg: #ffffff;
  --bg-card: #f6f8fa;
  --text: #1f2328;
  --text-muted: #57606a;
  --accent: #2e8555;
  --accent-hover: #29784c;
  --border: #d0d7de;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2rem;
  border-bottom: 1px solid var(--border);
}

.logo-link {
  display: flex;
  align-items: center;
}

.logo {
  height: 36px;
  width: auto;
}

.nav-link {
  color: var(--text);
  text-decoration: none;
  font-weight: 500;
}

.nav-link:hover {
  color: var(--accent);
}

.main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 3rem 2rem;
}

.hero {
  text-align: center;
  margin-bottom: 3rem;
}

.hero-title {
  font-size: 2rem;
  font-weight: 700;
  margin: 0 0 0.75rem;
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--text-muted);
  margin: 0;
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
}

.labs {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.lab-card {
  background: var(--bg-card);
  border-radius: 8px;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--border);
}

.lab-card-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 0.5rem;
}

.lab-card-description {
  color: var(--text-muted);
  font-size: 0.9375rem;
  line-height: 1.5;
  margin: 0 0 1.25rem;
  flex-grow: 1;
}

.lab-card-link {
  display: inline-block;
  background: var(--accent);
  color: #ffffff;
  text-decoration: none;
  font-weight: 600;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  text-align: center;
  transition: background 0.15s;
}

.lab-card-link:hover {
  background: var(--accent-hover);
}