/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

/* 动态背景 */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 50%, rgba(120, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 255, 255, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 40% 80%, rgba(120, 119, 198, 0.2) 0%, transparent 50%);
    animation: float 6s ease-in-out infinite;
    z-index: -1;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

.container {
    width: 100%;
    max-width: 420px;
    padding: 20px;
}

.login-box {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 20px;
    padding: 40px;
    box-shadow: 
        0 8px 32px rgba(31, 38, 135, 0.37),
        inset 0 1px 0 rgba(255, 255, 255, 0.3);
    transform: translateY(0);
    transition: all 0.3s ease;
}

.login-box:hover {
    transform: translateY(-5px);
    box-shadow: 
        0 15px 40px rgba(31, 38, 135, 0.4),
        inset 0 1px 0 rgba(255, 255, 255, 0.3);
}

.login-header {
    text-align: center;
    margin-bottom: 30px;
}

.login-header h2 {
    color: #4a5568;
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 8px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.login-header p {
    color: #718096;
    font-size: 14px;
    opacity: 0.8;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #4a5568;
    font-weight: 500;
    font-size: 14px;
}

.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    font-size: 16px;
    background: rgba(255, 255, 255, 0.8);
    transition: all 0.3s ease;
    outline: none;
}

.form-group input:focus {
    border-color: #667eea;
    background: rgba(255, 255, 255, 0.95);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.15);
}

.captcha-container {
    display: flex;
    gap: 10px;
    align-items: center;
}

.captcha-container input {
    flex: 1;
}

#captchaImage {
    width: 120px;
    height: 40px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
}

#captchaImage:hover {
    border-color: #667eea;
    transform: scale(1.05);
}

.error-message {
    color: #e53e3e;
    font-size: 14px;
    margin-bottom: 15px;
    padding: 10px;
    background: rgba(254, 178, 178, 0.2);
    border-radius: 8px;
    border-left: 4px solid #e53e3e;
    display: none;
}

.error-message.show {
    display: block;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.login-btn {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.login-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.login-btn:hover::before {
    left: 100%;
}

.login-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.login-btn:active {
    transform: translateY(0);
}

/* 响应式设计 */
@media (max-width: 480px) {
    .container {
        padding: 10px;
    }
    
    .login-box {
        padding: 30px 20px;
    }
    
    .login-header h2 {
        font-size: 24px;
    }
    
    .captcha-container {
        flex-direction: column;
        align-items: stretch;
    }
    
    #captchaImage {
        width: 100%;
        height: 50px;
    }
}

@media (max-width: 360px) {
    .login-box {
        padding: 25px 15px;
    }
    
    .form-group input {
        padding: 10px 12px;
        font-size: 14px;
    }
    
    .login-btn {
        padding: 12px;
        font-size: 14px;
    }
}

/* 加载动画 */
.loading {
    position: relative;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid transparent;
    border-top: 2px solid white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}