body {
            margin: 0;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background-color: #f5f7fa;
            color: #333;
        }

        .header {
            background-color: #0b0f1a;
            padding: 20px 40px;
            color: white;
            font-size: 24px;
            font-weight: bold;
            box-shadow: 0 2px 4px rgba(0,0,0,0.2);
        }

        .container {
            max-width: 400px;
            margin: 60px auto;
            background-color: white;
            border-radius: 10px;
            padding: 30px 40px;
            box-shadow: 0 8px 16px rgba(0,0,0,0.05);
        }

        h2 {
            margin-top: 0;
            color: #0b0f1a;
        }

        label {
            font-weight: 600;
            display: block;
            margin-bottom: 6px;
            color: #333;
        }

        input[type="text"],
        input[type="password"] {
            width: 100%;
            padding: 10px;
            border: 1px solid #ccc;
            border-radius: 6px;
            margin-bottom: 20px;
            font-size: 14px;
        }

        input[type="checkbox"] {
            margin-right: 6px;
        }

        .form-check {
            margin-bottom: 20px;
            font-size: 12px;
        }

        input[type="submit"] {
            background-color: #30d158; /* operational green */
            color: white;
            border: none;
            padding: 12px 20px;
            border-radius: 6px;
            cursor: pointer;
            font-weight: bold;
            transition: background-color 0.2s ease;
        }

        input[type="submit"]:hover {
            background-color: #28b84f;
        }

        /* Flash popup styling */
        .flash-popup {
            position: fixed;
            top: 20px;
            right: 20px;
            z-index: 9999;
        }

        .flash-message {
            background-color: #ff4d4f;
            color: white;
            padding: 14px 20px;
            margin-bottom: 10px;
            border-radius: 8px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.15);
            font-weight: bold;
            position: relative;
            animation: fadeInSlide 0.3s ease-out;
        }

        .flash-message .close-btn {
            position: absolute;
            top: 8px;
            right: 12px;
            background: none;
            border: none;
            color: white;
            font-size: 16px;
            cursor: pointer;
        }

        @keyframes fadeInSlide {
            0% {
                opacity: 0;
                transform: translateY(-10px);
            }
            100% {
                opacity: 1;
                transform: translateY(0);
            }
        }