.container {
    background-color: #fff;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    width: 320px;
    margin: auto;
    margin-top: 50px;
    font-family: Arial, sans-serif;
}
h2 {
    margin-bottom: 20px;
    font-size: 24px;
    text-align: center;
    color: #333;
}
.form-group {
    margin-bottom: 15px;
}
.form-group label {
    display: block;
    margin-bottom: 5px;
    color: #555;
}
.form-group input {
    width: 100%;
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    box-sizing: border-box;
}
.form-group input[type="submit"] {
    background-color: #007bff;
    color: #fff;
    border: none;
    cursor: pointer;
    padding: 10px;
    font-size: 16px;
}
.form-group input[type="submit"]:hover {
    background-color: #0056b3;
}
.form-group input[type="checkbox"] {
    width: auto;
    margin-right: 5px;
}
.form-group .checkbox-label {
    display: inline-block;
    margin-left: 5px;
    color: #555;
}

.form-group input[type="submit"].loading {
    background-color: #cccccc;
    cursor: not-allowed;
    position: relative;
}

.form-group input[type="submit"].loading::after {
    content: "";
    display: inline-block;
    width: 12px;
    height: 12px;
    margin-left: 10px;
    border: 2px solid #fff;
    border-radius: 50%;
    border-top-color: transparent;
    animation: spin 1s linear infinite;
}

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

.error-message {
    color: #d9534f;
    font-size: 12px;
    margin-top: 5px;
    display: none;
}

input.invalid {
    border: 1px solid #d9534f;
}

.password-requirements {
    font-size: 12px;
    color: #666;
    margin-top: 5px;
}

.form-group input[type="submit"].loading {
    background-color: #cccccc;
    cursor: not-allowed;
    position: relative;
    animation: buttonPulse 1.5s infinite;
}

@keyframes buttonPulse {
    0% { opacity: 1; }
    50% { opacity: 0.7; }
    100% { opacity: 1; }
}