:root {
  /* Base Variables */
  --border-radius: 0.5rem;
  --transition-speed: 0.3s;
  --font-family-sans: 'Inter', system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;

  /* DTU Brand Colors */
  --dtu-red: #990000;
  --dtu-orange: #FC7634;
  --dtu-navy: #030F4F;
  --dtu-blue: #2F3EEA;
  --dtu-green: #1FD082;
  --dtu-yellow: #F6D04D;

  /* Default Theme (Light) */
  --bg-body: #f8f9fa;
  --bg-surface: #ffffff;
  --bg-surface-rgb: 255, 255, 255;
  --bg-surface-secondary: #e9ecef;
  --text-main: #212529;
  --text-muted: #6c757d;

  /* Brand Mappings */
  --primary-color: var(--dtu-red);
  --primary-hover: #7a0000;
  /* Darker red */
  --primary-gradient: linear-gradient(90deg, var(--dtu-orange) 0%, var(--dtu-red) 100%);

  --border-color: #dee2e6;
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.1);
  --card-bg: #ffffff;
}

[data-theme="dark"] {
  /* Dark Theme Overrides */
  --bg-body: #0a0a0a;
  /* Very dark grey, almost black */
  --bg-surface: #1a1a1a;
  --bg-surface-rgb: 26, 26, 26;
  --bg-surface-secondary: #2d2d2d;
  --text-main: #e0e0e0;
  --text-muted: #a0a0a0;

  --primary-color: var(--dtu-orange);
  /* Orange pops better on dark */
  --primary-hover: #ff9159;
  --primary-gradient: linear-gradient(90deg, var(--dtu-orange) 0%, var(--dtu-red) 100%);

  --border-color: #404040;
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.5);
  --card-bg: #1a1a1a;
}

body {
  background-color: var(--bg-body);
  color: var(--text-main);
  font-family: var(--font-family-sans);
  transition: background-color var(--transition-speed), color var(--transition-speed);
}

a {
  color: var(--primary-color);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--primary-hover);
  text-decoration: underline;
}

/* Bootstrap Overrides for Theming */
.bg-light {
  background-color: var(--bg-body) !important;
}

.bg-white {
  background-color: var(--bg-surface) !important;
}

.text-muted {
  color: var(--text-muted) !important;
}

.card {
  background-color: var(--card-bg);
  border-color: var(--border-color);
  color: var(--text-main);
}

/* Custom Components */
/* Premium Button Styles */
.btn {
  border-radius: 50px;
  /* Pill shape */
  font-weight: 600;
  letter-spacing: 0.02em;
  padding: 0.5rem 1.25rem;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-sm);
  border: none;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn:active {
  transform: translateY(0);
}

.btn-sm {
  padding: 0.25rem 0.75rem;
  font-size: 0.875rem;
}

.btn-primary {
  background: var(--primary-gradient);
  color: white;
  border: none;
}

.btn-primary:hover {
  background: linear-gradient(90deg, var(--dtu-red) 0%, var(--dtu-orange) 100%);
  /* Reverse gradient on hover */
  color: white;
}

.btn-outline-primary {
  background: transparent;
  border: 2px solid var(--primary-color);
  color: var(--primary-color);
  box-shadow: none;
}

.btn-outline-primary:hover {
  background: var(--primary-color);
  color: var(--bg-surface);
  border-color: var(--primary-color);
}

/* Action Buttons (Success/Warning/Danger) */
.btn-success {
  background: var(--dtu-green);
  color: white;
}

.btn-warning {
  background: var(--dtu-yellow);
  color: #212529;
}

.btn-danger {
  background: var(--dtu-red);
  color: white;
}

.btn-info {
  background: var(--dtu-blue);
  color: white;
}

.clickable-card {
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
  border: 1px solid var(--border-color);
}

.clickable-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.nav-link {
  color: var(--text-main);
}

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

.nav-link.active {
  font-weight: bold;
  color: var(--primary-color) !important;
  border-bottom: 2px solid var(--primary-color);
}

/* Login Page Specifics */
.login-page {
  background: var(--primary-gradient);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.login-card {
  max-width: 400px;
  width: 100%;
  padding: 2rem;
  background: var(--bg-surface);
  border-radius: 10px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

.login-footer {
  position: absolute;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  color: rgba(255, 255, 255, 0.8);
}

/* Navbar Styling */
.navbar {
  background-color: var(--bg-surface) !important;
  border-bottom: 1px solid var(--border-color);
}

.navbar-light .navbar-nav .nav-link {
  color: var(--text-main);
}

.dropdown-menu {
  background-color: var(--bg-surface);
  border-color: var(--border-color);
}

.dropdown-item {
  color: var(--text-main);
}

.dropdown-item:hover {
  background-color: var(--bg-surface-secondary);
  color: var(--text-main);
}

/* Premium Visual Polish */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-main);
}

.card {
  border: none;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  overflow: hidden;
  /* For image zoom effects */
}

.clickable-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

/* Glassmorphism Utility */
.glass {
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.18);
}

[data-theme="dark"] .glass {
  background: rgba(30, 30, 30, 0.7);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

/* Gradient Text Utility */
.text-gradient {
  background: linear-gradient(45deg, var(--primary-color), var(--primary-hover));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Navbar Polish */
.navbar {
  backdrop-filter: blur(10px);
  background-color: rgba(var(--bg-surface-rgb), 0.9) !important;
  /* Requires RGB vars, falling back to solid for now */
  box-shadow: var(--shadow-sm);
}

/* Badge Polish */
.badge {
  font-weight: 600;
  letter-spacing: 0.05em;
  padding: 0.5em 0.8em;
}

/* Spacing Utilities */
.btn-group-gap>* {
  margin-right: 0.5rem;
}

.btn-group-gap>*:last-child {
  margin-right: 0;
}

/* Ensure form elements inside button groups also respect spacing */
form.d-inline {
  margin-right: 0.5rem;
}

form.d-inline:last-child {
  margin-right: 0;
}

.dropdown-divider {
  border-top-color: var(--border-color);
}