:root {
  color-scheme: light;
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --primary: #2563eb;
  --border: #e2e8f0;
  --accent: #8b5cf6;
}

html[data-bs-theme="dark"] {
  color-scheme: dark;
  --bg: #020617;
  --surface: #111827;
  --text: #f8fafc;
  --muted: #94a3b8;
  --primary: #60a5fa;
  --border: #1f2937;
  --accent: #c084fc;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  overflow-x: hidden;
}

.navbar, .card, .table, .form-control, .form-select, .btn {
  border-radius: 18px;
}

.hero-section {
  min-height: 80vh;
  display: grid;
  align-items: center;
}

.card {
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: 0 20px 45px rgba(15, 23, 42, 0.12);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 24px 55px rgba(37, 99, 235, 0.18);
}

.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  display: none;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: white;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 12px 32px rgba(37, 99, 235, 0.25);
}

.back-to-top.show { display: flex; }

@keyframes floatUp {
  0% { transform: translateY(20px); opacity: 0; }
  100% { transform: translateY(0); opacity: 1; }
}

[data-aos] {
  animation-name: floatUp;
}