body {
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      margin: 0;
      font-family: "Poppins", sans-serif;
      background: linear-gradient(135deg, #e0f2fe, #dbeafe, #f0f9ff);
      transition: background .3s, color .3s;
    }

    /* Dark Mode */
    body.dark-mode {
      background: #1f2937;
      color: #f9fafb;
    }

    .form-card-3d {
      background: rgba(255, 255, 255, 0.9);
      backdrop-filter: blur(12px);
      padding: 25px 20px;
      border-radius: 16px;
      box-shadow: 0 6px 18px rgba(59,130,246,0.12);
      width: 300px; /* largeur réduite */
      text-align: center;
      transition: .3s;
    }
    body.dark-mode .form-card-3d {
      background: rgba(55,65,81,0.9);
      color: #f9fafb;
    }

    .form-header i {
      font-size: 46px;
      color: #2563eb;
      margin-bottom: 10px;
    }
    body.dark-mode .form-header i {
      color: #60a5fa;
    }

    .form-header h1 {
      margin: 0;
      font-weight: 700;
      font-size: 1.4rem;
      color: #1e3a8a;
    }
    body.dark-mode .form-header h1 {
      color: #93c5fd;
    }

    .form-header p {
      margin: 6px 0 16px;
      font-size: 0.85rem;
      color: #4b5563;
    }
    body.dark-mode .form-header p {
      color: #d1d5db;
    }

    .form-group {
      position: relative;
      margin-bottom: 10px;
    }
    .form-group i {
      position: absolute;
      top: 50%;
      left: 10px;
      transform: translateY(-50%);
      color: #60a5fa;
      font-size: 14px;
    }

    .form-control {
      width: 85%; /* largeur réduite */
      padding: 10px 10px 10px 34px; /* padding réduit */
      border-radius: 8px;
      border: 1px solid #d1d5db;
      font-size: 13px;
      outline: none;
      transition: .3s;
    }
    .form-control:focus {
      border-color: #3b82f6;
      box-shadow: 0 0 4px rgba(59,130,246,0.25);
    }
    body.dark-mode .form-control {
      background: #374151;
      border: 1px solid #4b5563;
      color: #f9fafb;
    }

    .btn-3d {
      width: 92%; /* aligné sur la largeur input */
      padding: 11px;
      background: linear-gradient(135deg, #2563eb, #3b82f6);
      border: none;
      color: white;
      font-weight: 600;
      border-radius: 10px;
      cursor: pointer;
      margin-top: 12px;
      transition: 0.3s;
      font-size: 14px;
    }
    .btn-3d:hover {
      background: linear-gradient(135deg, #1e40af, #2563eb);
      transform: scale(1.02);
    }

    .secure-note {
      margin-top: 14px;
      font-size: 0.75rem;
      color: #16a34a;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 5px;
    }

    /* Toggle Dark Mode */
    .toggle-dark {
      position: absolute;
      top: 18px;
      right: 18px;
      background: #fff;
      border-radius: 50%;
      padding: 8px;
      cursor: pointer;
      box-shadow: 0 4px 10px rgba(0,0,0,0.1);
      transition: .3s;
      font-size: 14px;
      color: #2563eb;
    }
    body.dark-mode .toggle-dark {
      background: #374151;
      color: #f9fafb;
    }
    .toggle-dark:hover {
      transform: scale(1.1);
      background: #3b82f6;
      color: #fff;
    }