:root {
  --brand: #2563eb;
  --background: #f9fafb;
  --text: #222;
  --border: #e5e7eb;
  --card: #fff;
}
body {
  font-family: 'Segoe UI', 'Roboto', Arial, sans-serif;
  background: var(--background);
  color: var(--text);
  margin: 0;
  padding: 0;
}
header, nav {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.logo {
  height: 40px;
  vertical-align: middle;
}
nav a {
  color: var(--brand);
  text-decoration: none;
  margin: 0 1rem;
  font-weight: 600;
}
nav a:hover {
  text-decoration: underline;
}
.container {
  max-width: 600px;
  margin: 2rem auto;
  background: var(--card);
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.05);
  padding: 2rem;
}
h1, h2 {
  color: var(--brand);
}
input, select, textarea, button {
  width: 100%;
  padding: 0.75rem;
  margin-bottom: 1rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  background: #fff;
}
button {
  background: var(--brand);
  color: #fff;
  font-weight: bold;
  cursor: pointer;
  border: none;
  transition: background 0.2s;
}
button:hover {
  background: #1e40af;
}
.alert {
  padding: 1rem;
  background: #fef3c7;
  color: #b45309;
  border-radius: 8px;
  margin-bottom: 1rem;
}
.success {
  background: #d1fae5;
  color: #065f46;
}
.dark-mode {
  --brand: #60a5fa;
  --background: #18181b;
  --text: #e5e7eb;
  --border: #374151;
  --card: #23272b;
  background: var(--background);
  color: var(--text);
}
@media (max-width: 700px) {
  .container {
    max-width: 95vw;
    padding: 1rem;
  }
  header, nav {
    flex-direction: column;
    padding: 1rem;
  }
}