/* Login Screen */
    #loginScreen {
        display: flex;
        justify-content: center;
        align-items: center;
        min-height: 100vh;
    }
    
    .login-container {
        background: white;
        padding: 40px;
        border-radius: 15px;
        box-shadow: 0 15px 35px rgba(0,0,0,0.2);
        width: 90%;
        max-width: 400px;
    }
    
    .login-container h1 {
        text-align: center;
        color: #333;
        margin-bottom: 30px;
    }
    
    .form-group {
        margin-bottom: 20px;
    }
    
    .form-group label {
        display: block;
        margin-bottom: 8px;
        color: #555;
        font-weight: 500;
    }
    
    .form-group input {
        width: 100%;
        padding: 12px;
        border: 2px solid #e0e0e0;
        border-radius: 8px;
        font-size: 15px;
        transition: border 0.3s;
    }
    
    .form-group input:focus {
        outline: none;
        border-color: #667eea;
    }
    
    .btn-login {
        width: 100%;
        padding: 14px;
        background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        color: white;
        border: none;
        border-radius: 8px;
        font-size: 17px;
        font-weight: 600;
        cursor: pointer;
        transition: transform 0.2s;
    }
    
    .btn-login:hover {
        transform: translateY(-2px);
    }
    
    .btn-login:disabled {
        opacity: 0.6;
        cursor: not-allowed;
    }
    
    .error-message {
        color: #e74c3c;
        text-align: center;
        margin-top: 15px;
        font-size: 15px;
    }