:root{
    --bg-body: #f6f8fb;
    --bg-page: linear-gradient(180deg,#f7fafc 0%, #eef4f9 100%);
    --card-bg: #ffffff;
    --card-border: rgba(15,23,36,0.06);
    --text-primary: #0f1724;
    --text-muted: #616f7c;
    --accent: #0b5ed7;
    --success: #0f9d58;
    --input-bg: #ffffff;
    --input-border: rgba(15,23,36,0.08);
    --placeholder: rgba(15,23,36,0.4);
    --link-color: #0b5ed7;
    --shadow: 0 6px 20px rgba(15,23,36,0.06);
    --alert-bg: rgba(11,94,215,0.06);
    --alert-text: #0b5ed7;
  }
  
  /* ------------------------
     Dark mode variables
     ------------------------ */
  body.dark-mode {
    --bg-body: #071018;
    --bg-page: linear-gradient(180deg,#071018 0%, #0b1420 100%);
    --card-bg: rgba(255,255,255,0.03);
    --card-border: rgba(255,255,255,0.04);
    --text-primary: #e6eef6;
    --text-muted: #9aa6b2;
    --accent: #4da3ff;
    --success: #0f9d58;
    --input-bg: rgba(255,255,255,0.02);
    --input-border: rgba(255,255,255,0.04);
    --placeholder: rgba(230,238,246,0.45);
    --link-color: #89baff;
    --shadow: 0 6px 20px rgba(2,6,8,0.6);
    --alert-bg: rgba(77,163,255,0.06);
    --alert-text: #aee0ff;
  }
  
  /* Ensure explicit light-mode class too (for toggling) */
  body.light-mode {
    /* uses :root vars */
  }
  
  /* Page background */
  .login-bg {
    background: var(--bg-page);
    min-height: 100vh;
    color: var(--text-primary);
    transition: background-color .25s ease, color .25s ease;
  }
  
  /* Container */
  .login-container {
    padding: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  
  /* Card */
  .login-card {
    width: 380px;
    border-radius: 12px;
    overflow: hidden;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    box-shadow: var(--shadow);
    transition: background-color .22s ease, border-color .22s ease, color .22s ease;
  }
  
  .login-card .card-body {
    padding: 20px;
  }
  
  /* Text colors */
  .login-card .card-title,
  .login-card label,
  .login-card .text-center,
  .login-card .small {
    color: var(--text-primary);
  }
  
  .login-card .text-center.small.muted {
    color: var(--text-muted);
  }
  
  /* Inputs */
  .login-card .form-control {
    background: var(--input-bg);
    border: 1px solid var(--input-border);
    color: var(--text-primary);
    transition: background-color .18s ease, border-color .18s ease, color .18s ease;
  }
  .login-card .form-control::placeholder {
    color: var(--placeholder);
  }
  
  /* Buttons */
  .login-card .btn-primary {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
  }
  .login-card .btn-primary:hover {
    filter: brightness(.96);
  }
  
  /* Theme switcher layout */
  .theme-switcher {
    font-size: .9rem;
    gap: .4rem;
  }
  .theme-switcher .form-check-input {
    width: 2rem;
    height: 1.25rem;
  }
  
  /* Messages / alerts */
  #messages .alert {
    margin-bottom: 0;
    border: 1px solid transparent;
    background: var(--alert-bg);
    color: var(--alert-text);
  }
  
  /* Make link/button contrasts good on dark */
  .login-card .btn, .login-card .form-control, .login-card .alert {
    transition: background-color .18s ease, border-color .18s ease, color .18s ease;
  }
  
  /* Small responsive fix */
  @media (max-width: 480px) {
    .login-card { width: 92%; }
  }
  
  /* Provide specific high contrast for inputs in dark-mode */
  body.dark-mode .login-card .form-control {
    background: var(--input-bg);
    border-color: var(--input-border);
    color: var(--text-primary);
  }
  
  /* Provide accessible focus styles */
  .login-card .form-control:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(11,94,215,0.08);
    border-color: var(--accent);
  }
  
  /* Alerts override for error (danger) to be visible in both modes */
  #messages .alert-danger {
    background: rgba(255,90,90,0.06);
    color: #ffdddd;
    border: 1px solid rgba(255,90,90,0.12);
  }
  body.light-mode #messages .alert-danger {
    background: rgba(255,90,90,0.07);
    color: #641414;
    border: 1px solid rgba(255,90,90,0.12);
  }
  
  /* Success alert visible in both modes */
  #messages .alert-success {
    background: rgba(15,157,88,0.06);
    color: #ddffea;
    border: 1px solid rgba(15,157,88,0.12);
  }
  body.light-mode #messages .alert-success {
    background: rgba(15,157,88,0.06);
    color: #0f6b3e;
    border: 1px solid rgba(15,157,88,0.12);
  }