:root {
            --primary-color: #1a73e8;
            --dark-color: #0d47a1;
            --accent-color: #ff9800;
            --light-color: #f5f5f5;
            --text-dark: #333;
            --shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
            --success-color: #4caf50;
            --error-color: #f44336;
            --warning-color: #ff9800;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        body {
            background: linear-gradient(135deg, var(--dark-color) 0%, var(--primary-color) 100%);
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            padding: 20px;
        }

        .container {
            background: white;
            border-radius: 15px;
            box-shadow: var(--shadow);
            overflow: hidden;
            width: 100%;
            max-width: 450px;
        }

        .header {
            background: var(--dark-color);
            color: white;
            padding: 2rem;
            text-align: center;
        }

        .header h1 {
            font-size: 1.8rem;
            margin-bottom: 0.5rem;
        }

        .header p {
            opacity: 0.9;
        }

        .form-container {
            padding: 2rem;
        }

        .form-group {
            margin-bottom: 1.5rem;
            position: relative;
        }

        label {
            display: block;
            margin-bottom: 0.5rem;
            font-weight: 500;
            color: var(--text-dark);
        }

        input {
            width: 100%;
            padding: 12px 15px;
            border: 2px solid #e1e5e9;
            border-radius: 8px;
            font-size: 1rem;
            transition: border-color 0.3s;
        }

        input:focus {
            outline: none;
            border-color: var(--primary-color);
        }

        input.error {
            border-color: var(--error-color);
        }

        .btn {
            background: var(--primary-color);
            color: white;
            border: none;
            padding: 12px 20px;
            border-radius: 8px;
            font-size: 1rem;
            font-weight: 500;
            cursor: pointer;
            transition: background 0.3s;
            width: 100%;
            position: relative;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        .btn:hover {
            background: var(--dark-color);
        }

        .btn:disabled {
            background: #cccccc;
            cursor: not-allowed;
        }

        .register-link {
            text-align: center;
            margin-top: 1.5rem;
        }

        .register-link a {
            color: var(--primary-color);
            text-decoration: none;
            font-weight: 500;
        }

        .register-link a:hover {
            text-decoration: underline;
        }

        .message {
            padding: 10px 15px;
            border-radius: 5px;
            margin-bottom: 1rem;
            display: none;
        }

        .error-message {
            background: #ffebee;
            color: var(--error-color);
            border-left: 4px solid var(--error-color);
        }

        .success-message {
            background: #e8f5e9;
            color: var(--success-color);
            border-left: 4px solid var(--success-color);
        }

        .warning-message {
            background: #fff3e0;
            color: var(--warning-color);
            border-left: 4px solid var(--warning-color);
        }

        .loading {
            display: inline-block;
            width: 20px;
            height: 20px;
            border: 3px solid rgba(255,255,255,.3);
            border-radius: 50%;
            border-top-color: #fff;
            animation: spin 1s ease-in-out infinite;
            margin-right: 10px;
        }

        @keyframes spin {
            to { transform: rotate(360deg); }
        }

        .password-toggle {
            position: absolute;
            right: 12px;
            top: 38px;
            cursor: pointer;
            color: #777;
        }

        .forgot-password {
            text-align: right;
            margin-top: 5px;
        }

        .forgot-password a {
            color: var(--primary-color);
            text-decoration: none;
            font-size: 0.9rem;
        }

        .forgot-password a:hover {
            text-decoration: underline;
        }

        @media (max-width: 480px) {
            .container {
                margin: 10px;
            }
            
            .header, .form-container {
                padding: 1.5rem;
            }
        }