:root {
  --bg-primary: #0a0e14;
  --bg-secondary: #111820;
  --bg-tertiary: #1a2332;
  --border: #1e2a3a;
  --border-light: #2a3a4f;
  --text-primary: #c9d1d9;
  --text-secondary: #6b7d93;
  --text-muted: #4a5a6e;
  --accent: #00d4aa;
  --accent-dim: #00d4aa33;
  --accent-hover: #00f0c0;
  --danger: #ff6b6b;
  --danger-dim: #ff6b6b33;
  --warning: #f0c040;
  --success: #00d4aa;
  --font-body: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --transition: 0.2s ease;
  --max-width: 1200px;
  --nav-height: 64px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--accent); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent-hover); }

/* Navbar */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 14, 20, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  height: var(--nav-height);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
}

.brand-icon { color: var(--accent); }
.brand-accent { color: var(--accent); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
  list-style: none;
}

.nav-link {
  padding: 8px 14px;
  color: var(--text-secondary);
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}

.nav-link:hover, .nav-link.active { color: var(--text-primary); background: var(--bg-tertiary); }
.nav-admin { color: var(--warning) !important; }

.nav-user {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: 8px;
  padding-left: 16px;
  border-left: 1px solid var(--border);
}

.nav-username {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  transition: var(--transition);
}

/* Main */
.main-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 24px 64px;
  min-height: calc(100vh - var(--nav-height) - 60px);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary { background: var(--accent); color: var(--bg-primary); }
.btn-primary:hover { background: var(--accent-hover); color: var(--bg-primary); }

.btn-outline {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}
.btn-outline:hover { background: var(--accent-dim); }

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid transparent;
}
.btn-ghost:hover { color: var(--text-primary); background: var(--bg-tertiary); }

.btn-danger { background: var(--danger); color: white; }
.btn-danger:hover { opacity: 0.85; }

.btn-sm { padding: 6px 12px; font-size: 0.8rem; }
.btn-lg { padding: 14px 28px; font-size: 1rem; }
.btn-block { width: 100%; }

.inline-form { display: inline; }

/* Forms */
.form-group { margin-bottom: 16px; }
.form-group label {
  display: block;
  margin-bottom: 6px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 10px 14px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 0.9rem;
  transition: border-color var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-dim);
}

.form-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  padding-top: 28px;
}

/* Flash */
.flash {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  border-radius: var(--radius);
  margin-bottom: 24px;
  font-size: 0.9rem;
  animation: slideDown 0.3s ease;
}

.flash-success { background: var(--accent-dim); border: 1px solid var(--accent); color: var(--accent); }
.flash-error { background: var(--danger-dim); border: 1px solid var(--danger); color: var(--danger); }

.flash-close {
  background: none;
  border: none;
  color: inherit;
  font-size: 1.2rem;
  cursor: pointer;
  opacity: 0.7;
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Page header */
.page-header { margin-bottom: 32px; }
.page-header h1 { font-size: 2rem; font-weight: 700; margin-bottom: 4px; }
.page-subtitle { color: var(--text-secondary); font-size: 0.95rem; }
.flex-header { display: flex; justify-content: space-between; align-items: flex-start; flex-wrap: wrap; gap: 16px; }

/* Stats */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 16px;
  margin-bottom: 32px;
}

.stat-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-align: center;
  transition: border-color var(--transition);
}

.stat-card:hover { border-color: var(--border-light); }
.stat-value { font-family: var(--font-mono); font-size: 2rem; font-weight: 700; color: var(--accent); }
.stat-label { font-size: 0.85rem; color: var(--text-secondary); margin-top: 4px; }

/* Panels */
.panel {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 24px;
}

.panel-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

/* Challenge cards */
.challenges-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}

.challenge-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all var(--transition);
}

.challenge-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.challenge-card.solved { border-color: var(--accent-dim); }

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.card-title { font-size: 1.15rem; font-weight: 600; margin-bottom: 12px; }

.card-meta {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.category-badge {
  display: inline-block;
  padding: 3px 10px;
  background: var(--bg-tertiary);
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.points-badge {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 600;
}

.solved-badge { color: var(--success); font-size: 0.8rem; font-weight: 600; }
.type-badge {
  font-size: 0.75rem;
  padding: 3px 8px;
  background: #6366f133;
  color: #818cf8;
  border-radius: 20px;
  font-weight: 600;
}

.difficulty {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.diff-easy { color: #4ade80; }
.diff-medium { color: var(--warning); }
.diff-hard { color: var(--danger); }

/* Category filter */
.category-filter {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.filter-btn {
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  transition: all var(--transition);
}

.filter-btn:hover, .filter-btn.active {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-dim);
}

/* Dashboard */
.dashboard-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
  margin-bottom: 32px;
}

.activity-list { list-style: none; }
.activity-item {
  display: flex;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
}
.activity-item:last-child { border-bottom: none; }

.activity-icon {
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-size: 0.8rem;
  flex-shrink: 0;
}
.activity-icon.success { background: var(--accent-dim); color: var(--success); }
.activity-icon.fail { background: var(--danger-dim); color: var(--danger); }

.activity-info a { font-weight: 500; }
.activity-meta { display: block; font-size: 0.8rem; color: var(--text-muted); margin-top: 2px; }

.quick-actions { display: flex; gap: 12px; flex-wrap: wrap; }

/* Challenge detail */
.detail-header { margin-bottom: 32px; }
.detail-header h1 { font-size: 2rem; margin: 12px 0 4px; }
.detail-meta { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.detail-solves { color: var(--text-secondary); font-size: 0.9rem; }

.detail-grid {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 24px;
}

.challenge-description { line-height: 1.8; color: var(--text-primary); }
.challenge-description code {
  font-family: var(--font-mono);
  background: var(--bg-primary);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.9em;
}

.instance-panel { border-color: #6366f144; }
.instance-info { margin-bottom: 16px; }
.instance-status { display: flex; align-items: center; gap: 8px; font-weight: 600; margin-bottom: 8px; }
.instance-status.running { color: var(--success); }
.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--success);
  animation: pulse 2s infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.instance-link { font-family: var(--font-mono); word-break: break-all; }
.instance-expiry { color: var(--text-secondary); font-size: 0.85rem; }
.instance-actions { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.instance-desc { color: var(--text-secondary); margin-bottom: 16px; }

.flag-form input { font-family: var(--font-mono); }
.solved-panel { text-align: center; color: var(--success); font-weight: 600; padding: 32px; }

.hint-details summary {
  cursor: pointer;
  color: var(--warning);
  font-weight: 500;
  padding: 8px 0;
}
.hint-details p { margin-top: 8px; color: var(--text-secondary); }

.submission-list { list-style: none; }
.submission-item {
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}
.submission-item:last-child { border-bottom: none; }
.submission-item code { font-size: 0.85rem; }
.submission-meta { display: block; font-size: 0.75rem; color: var(--text-muted); margin-top: 4px; }
.submission-item.correct code { color: var(--success); }
.submission-item.incorrect code { color: var(--danger); }

/* Leaderboard */
.leaderboard-table .rank-cell { font-family: var(--font-mono); font-weight: 700; width: 60px; }
.score-cell { font-family: var(--font-mono); font-weight: 600; color: var(--accent); }
.top-rank { background: var(--accent-dim); }

/* Profile */
.profile-header {
  display: flex;
  gap: 24px;
  align-items: center;
  margin-bottom: 32px;
}

.profile-avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--accent-dim);
  border: 2px solid var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent);
  flex-shrink: 0;
}

.profile-info h1 { font-size: 1.8rem; margin-bottom: 4px; }
.profile-meta { color: var(--text-secondary); font-size: 0.9rem; }
.profile-bio { margin-top: 8px; color: var(--text-secondary); }

.role-badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
}
.role-badge.admin { background: #f0c04033; color: var(--warning); }

.profile-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

/* Auth */
.auth-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - var(--nav-height) - 120px);
}

.auth-card {
  width: 100%;
  max-width: 420px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 40px;
}

.auth-title { font-size: 1.6rem; font-weight: 700; margin-bottom: 4px; }
.auth-subtitle { color: var(--text-secondary); margin-bottom: 28px; }
.auth-footer { text-align: center; margin-top: 20px; font-size: 0.9rem; color: var(--text-secondary); }

/* Tables */
.table-responsive { overflow-x: auto; }

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.data-table th {
  text-align: left;
  padding: 12px 16px;
  font-weight: 600;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.data-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
}

.data-table tbody tr:hover { background: var(--bg-tertiary); }
.actions-cell { display: flex; gap: 4px; flex-wrap: wrap; align-items: center; }

.status-badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
}
.status-badge.active { background: var(--accent-dim); color: var(--success); }
.status-badge.inactive { background: var(--danger-dim); color: var(--danger); }

/* Admin */
.admin-nav-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
}

.admin-nav-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: all var(--transition);
  color: var(--text-primary);
}

.admin-nav-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.admin-nav-card h3 { margin-bottom: 8px; color: var(--accent); }
.admin-nav-card p { color: var(--text-secondary); font-size: 0.9rem; }

.admin-form .form-actions {
  display: flex;
  gap: 12px;
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
}

.docker-fields {
  padding: 16px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 16px;
}

/* Error */
.error-page {
  text-align: center;
  padding: 80px 24px;
}

.error-code {
  font-family: var(--font-mono);
  font-size: 5rem;
  font-weight: 700;
  color: var(--accent);
  opacity: 0.3;
  line-height: 1;
}

.error-page h1 { font-size: 1.5rem; margin: 16px 0 8px; }
.error-page p { color: var(--text-secondary); margin-bottom: 24px; }

/* Empty states */
.empty-state { color: var(--text-muted); font-size: 0.9rem; }
.empty-state-box {
  text-align: center;
  padding: 48px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  color: var(--text-secondary);
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 24px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* Responsive */
@media (max-width: 768px) {
  .nav-toggle { display: flex; }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px;
    gap: 4px;
  }

  .nav-links.open { display: flex; }
  .nav-user { border-left: none; padding-left: 0; margin-left: 0; }

  .detail-grid { grid-template-columns: 1fr; }
  .page-header h1 { font-size: 1.5rem; }
  .stat-value { font-size: 1.5rem; }
  .profile-header { flex-direction: column; text-align: center; }
}