.auth-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 2rem;
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e9f2 100%);
}

.auth-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 400px;
}

.auth-card h1 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

.auth-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    color: #666;
    font-size: 0.9rem;
}

.form-group input {
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

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

.auth-button {
    background: var(--gradient);
    color: white;
    border: none;
    padding: 1rem;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.auth-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(41,98,255,0.2);
}

.auth-link {
    text-align: center;
    margin-top: 1.5rem;
    color: #666;
}

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

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

.form-group input[name="invite_code"] {
    letter-spacing: 2px;
    font-family: monospace;
}

.form-group label[for="invite_code"] {
    color: #e91e63;
}

.invite-code-tip {
    margin-top: 0.5rem;
    padding: 0.8rem;
    background: #f5f7fa;
    border-radius: 8px;
    text-align: center;
}

.invite-code-tip p {
    color: #666;
    margin-bottom: 0.5rem;
}

.join-qq-btn {
    display: inline-block;
    background: var(--gradient);
    color: white;
    padding: 0.8rem 1.5rem;
    border-radius: 20px;
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.join-qq-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(41,98,255,0.2);
}

.qq-group-number {
    display: block;
    font-size: 0.8rem;
    margin-top: 0.3rem;
    opacity: 0.9;
}

@media (max-width: 480px) {
    .auth-container {
        padding: 1rem;
    }
    
    .auth-card {
        padding: 1.5rem;
    }
}