:root {
  --bg-color: #0b111a;
  --card-bg: rgba(255, 255, 255, 0.03);
  --card-border: rgba(255, 255, 255, 0.08);
  --primary-accent: #3b82f6;
  --secondary-accent: #6366f1;
  --text-main: #f3f4f6;
  --text-dim: #9ca3af;
  --status-active: #10b981;
  --status-pending: #f59e0b;
  --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body.light-mode {
  --bg-color: #f8fafc;
  --card-bg: #ffffff;
  --card-border: #e2e8f0;
  --text-main: #1e293b;
  --text-dim: #64748b;
  --glass-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

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

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  font-family: var(--font-family);
  line-height: 1.6;
  padding: 40px 20px;
}

header {
  text-align: center;
  margin-bottom: 60px;
  position: relative;
}

.controls {
  position: absolute;
  top: 0;
  right: 0;
  display: flex;
  gap: 12px;
}

.btn-ctrl {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  color: var(--text-main);
  padding: 8px 16px;
  border-radius: 12px;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  backdrop-filter: blur(8px);
}

.btn-ctrl:hover {
  background: rgba(255, 255, 255, 0.1);
  transform: translateY(-2px);
}

.btn-ctrl:active {
  transform: scale(0.95);
}

.btn-refresh.loading {
  opacity: 0.7;
  cursor: wait;
}

.btn-refresh.loading i {
  animation: spin 1s linear infinite;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

h1 {
  font-size: 2.5rem;
  letter-spacing: -0.025em;
  background: linear-gradient(to right, #60a5fa, #a78bfa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 10px;
}

p.subtitle {
  color: var(--text-dim);
  font-weight: 600;
}

.secret-refresh {
  cursor: default;
  display: inline-block;
  user-select: none;
  -webkit-user-select: none;
}

.dashboard-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 25px;
  max-width: 1400px;
  margin: 0 auto;
}

.card {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  overflow: hidden;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  display: flex;
  flex-direction: column;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.2);
  border-color: rgba(255, 255, 255, 0.15);
}

.preview-container {
  height: 180px;
  position: relative;
  background: #1a1e26;
  overflow: hidden;
}

.preview-container img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.card:hover .preview-container img {
  transform: scale(1.05);
}

.no-preview {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--text-dim);
  font-size: 0.85rem;
  background: linear-gradient(45deg, #161b22, #0d1117);
}

.card-content {
  padding: 24px;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 15px;
}

.student-name {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-main);
}

.status-badge {
  padding: 4px 10px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.status-active {
  background: rgba(16, 185, 129, 0.1);
  color: var(--status-active);
  border: 1px solid rgba(16, 185, 129, 0.2);
}

.status-pending {
  background: rgba(245, 158, 11, 0.1);
  color: var(--status-pending);
  border: 1px solid rgba(245, 158, 11, 0.2);
}

.url-link {
  font-size: 0.85rem;
  color: var(--text-dim);
  text-decoration: none;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 20px;
  display: block;
}

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

.preview-link {
  text-decoration: none;
  cursor: pointer;
  display: block;
}

.preview-link.disabled {
  pointer-events: none;
  cursor: default;
}

@media (max-width: 768px) {
  .dashboard-grid {
    grid-template-columns: 1fr;
  }
}