* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', Arial, sans-serif;
    background: #f5f7fa;
    color: #333;
    line-height: 1.5;
    font-size: 13px;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.login-box {
    background: #fff;
    padding: 32px;
    border-radius: 6px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    width: 380px;
    border: 1px solid #e8eaed;
}

.login-header {
    text-align: center;
    margin-bottom: 24px;
}

.login-header h2 {
    color: #202124;
    font-size: 20px;
    font-weight: 500;
    margin-bottom: 6px;
}

.login-header p {
    color: #5f6368;
    font-size: 13px;
    margin: 0;
}

.login-header i {
    color: #1a73e8;
    font-size: 32px;
    margin-bottom: 12px;
    display: block;
}

.form-group {
    margin-bottom: 16px;
}

.form-group label {
    font-weight: 500;
    color: #202124;
    font-size: 12px;
    margin-bottom: 5px;
    display: block;
}

.form-control {
    border-radius: 4px;
    border: 1px solid #dadce0;
    padding: 10px 12px;
    font-size: 13px;
    transition: border-color 0.2s;
}

.form-control:focus {
    border-color: #1a73e8;
    outline: none;
    box-shadow: 0 0 0 2px rgba(26, 115, 232, 0.1);
}

.form-control::placeholder {
    color: #9aa0a6;
}

.btn-login {
    background: #1a73e8;
    border: none;
    padding: 10px;
    font-size: 13px;
    font-weight: 500;
    border-radius: 4px;
    width: 100%;
    transition: background 0.2s;
}

.btn-login:hover {
    background: #1557b0;
}

.btn-login i {
    margin-right: 6px;
}

.captcha-box {
    display: flex;
    align-items: center;
    gap: 8px;
}

.captcha-box input {
    flex: 1;
}

.captcha-box img {
    cursor: pointer;
    border-radius: 4px;
    border: 1px solid #dadce0;
    height: 38px;
}

.text-center {
    text-align: center;
}

.mt-3 {
    margin-top: 16px;
}

.text-muted {
    color: #5f6368;
    font-size: 12px;
    text-decoration: none;
    transition: color 0.2s;
}

.text-muted:hover {
    color: #1a73e8;
}

.btn-loading {
    position: relative;
    pointer-events: none;
}

.btn-loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 16px;
    height: 16px;
    margin: -8px 0 0 -8px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s linear infinite;
}

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