:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --secondary: #64748b;
  --bg: #f8fafc;
  --card: #ffffff;
  --border: #e2e8f0;
  --text: #0f172a;
  --text-muted: #64748b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.95);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

.header a.brand {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
}

.nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav a {
  color: var(--secondary);
  text-decoration: none;
  font-size: 0.9375rem;
}

.nav a:hover {
  color: var(--text);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 1rem;
  font-size: 0.9375rem;
  font-weight: 500;
  border-radius: 0.5rem;
  border: none;
  cursor: pointer;
  text-decoration: none;
  transition: background 0.2s;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover:not(:disabled) {
  background: var(--primary-dark);
}

.btn-secondary {
  background: #e2e8f0;
  color: #334155;
}

.btn-secondary:hover:not(:disabled) {
  background: #cbd5e1;
}

/* Card */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  padding: 1.5rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}

.card:hover {
  box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
}

/* Form */
.input {
  width: 100%;
  padding: 0.5rem 1rem;
  font-size: 1rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  margin-top: 0.25rem;
}

.input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.2);
}

label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: #374151;
  margin-bottom: 0.25rem;
}

.form-group {
  margin-bottom: 1rem;
}

/* Grid */
.grid {
  display: grid;
  gap: 1.5rem;
}

.grid-3 {
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}

/* Utility */
.text-muted { color: var(--text-muted); }
.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-4 { margin-top: 1rem; }
.mt-6 { margin-top: 1.5rem; }
.mb-4 { margin-bottom: 1rem; }
.line-clamp-2 {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* Alert */
.alert {
  padding: 0.75rem 1rem;
  border-radius: 0.5rem;
  margin-bottom: 1rem;
}

.alert-error {
  background: #fef2f2;
  color: #b91c1c;
}

.alert-success {
  background: #f0fdf4;
  color: #166534;
}