body {
    background-color: var(--light-bg);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 48rem; /* 768px */
    margin: 0 auto;
    padding: 0 clamp(0.75rem, 3vw, 1rem);
}

/* 头部 */
.page-header {
    background: var(--card-bg);
    padding: clamp(0.75rem, 3vw, 1rem) 0;
    margin-bottom: clamp(0.5rem, 2vw, 1rem);
    border-bottom: 0.0625rem solid var(--border-color); /* 1px */
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.page-title {
    font-size: clamp(1.25rem, 4vw, 1.5rem);
    font-weight: 600;
    color: var(--text-primary);
}

.homepage_btn {
    color: var(--primary-color);
}


/* 主要内容 */
.main-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: calc(100vh - 7.5rem);
    padding: 1rem 0;
}

/* 表单卡片 */
.form-container {
    background: var(--card-bg);
    border-radius: clamp(0.5rem, 2vw, 0.75rem);
    padding: clamp(1rem, 4vw, 1.5rem);
    margin-bottom: clamp(1rem, 4vw, 1.5rem);
    box-shadow: 0 0.125rem clamp(0.25rem, 1vw, 0.5rem) rgba(0,0,0,0.08);
    width: 100%;
    max-width: 25rem;
}

/* 页面切换 */
.form-tabs {
    display: flex;
    border-bottom: 0.0625rem solid var(--border-color);
}

.form-tab {
    flex: 1;
    text-align: center;
    padding: clamp(0.75rem, 3vw, 1rem) 0;
    font-size: clamp(0.875rem, 3.5vw, 1rem);
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    border-bottom: 0.125rem solid transparent;
    transition: all 0.3s ease;
}

.form-tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

/* 表单页面 */
.form-page {
    display: none;
}

.form-page.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(0.625rem); }
    to { opacity: 1; transform: translateY(0); }
}

.form-header {
    text-align: center;
    margin-bottom: clamp(0.5rem, 6vw, 0.8rem);
}

.form-logo {
    font-size: clamp(2.5rem, 10vw, 3rem);
    margin-bottom: 0.75rem;
    color: var(--primary-color);
}

.form-title {
    font-size: clamp(1.25rem, 5vw, 1.5rem);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.form-subtitle {
    font-size: clamp(0.875rem, 3.5vw, 1rem);
    color: var(--text-secondary);
}

/* 表单组 */
.form-group {
    margin-bottom: clamp(0.75rem, 3vw, 1rem);
}

.form-label {
    display: block;
    font-size: clamp(0.75rem, 3vw, 0.875rem);
    font-weight: 500;
    margin-bottom: clamp(0.25rem, 1vw, 0.375rem);
    color: var(--text-primary);
}

.form-input {
    width: 100%;
    padding: clamp(0.625rem, 2.5vw, 0.75rem) clamp(0.75rem, 3vw, 1rem);
    border: 0.125rem solid var(--border-color); /* 2px */
    border-radius: clamp(0.375rem, 1.5vw, 0.5rem);
    font-size: clamp(0.875rem, 3.5vw, 1rem);
    background: var(--card-bg);
    transition: all 0.2s ease;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.1875rem rgba(0, 122, 255, 0.1); /* 3px */
}

.input-group {
    position: relative;
}

.input-icon {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
}

.input-icon + .form-input {
    padding-left: 3rem;
}

.password-toggle {
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 1.25rem;
}

.password-toggle:hover {
    color: var(--text-primary);
}

/* 短信验证码 */
.sms-group {
    display: flex;
    gap: clamp(0.5rem, 2vw, 0.75rem);
}

.sms-input {
    flex: 1;
}

.sms-btn {
    padding: 0 clamp(0.75rem, 3vw, 1rem);
    background-color: var(--card-bg);
    border: 0.125rem solid var(--primary-color); /* 2px */
    color: var(--primary-color);
    border-radius: clamp(0.375rem, 1.5vw, 0.5rem);
    font-size: clamp(0.75rem, 3vw, 0.875rem);
    cursor: pointer;
    transition: all 0.2s ease;
    white-space: nowrap;
    font-weight: 600;
}

.sms-btn:hover:not(:disabled) {
    background-color: var(--primary-color);
    color: white;
}

.sms-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    border-color: var(--border-color);
    color: var(--text-secondary);
}

/* 复选框 */
.checkbox-group {
    display: flex;
    align-items: center;
    margin-bottom: clamp(1rem, 4vw, 1.5rem);
}

.checkbox {
    appearance: none;
    width: clamp(1.125rem, 4.5vw, 1.25rem);
    height: clamp(1.125rem, 4.5vw, 1.25rem);
    border: 0.125rem solid var(--border-color); /* 2px */
    border-radius: 0.25rem;
    cursor: pointer;
    position: relative;
    margin-right: 0.5rem;
}

.checkbox:checked {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}

.checkbox:checked::after {
    content: "✓";
    color: white;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 0.75rem;
}

.checkbox-label {
    font-size: clamp(0.75rem, 3vw, 0.875rem);
    color: var(--text-secondary);
    cursor: pointer;
}

/* 忘记密码链接 */
.forgot-password {
    font-size: clamp(0.75rem, 3vw, 0.875rem);
    color: var(--primary-color);
    text-decoration: none;
    margin-left: auto;
}

.forgot-password:hover {
    text-decoration: underline;
}

/* 按钮 */
.form-actions {
    display: flex;
    flex-direction: column;
    gap: clamp(0.75rem, 3vw, 1rem);
    margin-top: clamp(1rem, 4vw, 1.5rem);
}

.btn {
    padding: clamp(0.75rem, 3vw, 1rem) clamp(1rem, 4vw, 1.5rem);
    border: none;
    border-radius: clamp(0.375rem, 1.5vw, 0.5rem);
    font-size: clamp(0.875rem, 3.5vw, 1rem);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: center;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: #0056cc;
    transform: translateY(-0.0625rem); /* -1px */
    box-shadow: 0 0.25rem 0.75rem rgba(0, 122, 255, 0.3); /* 0 4px 12px */
}

.btn-secondary {
    background: var(--card-bg);
    color: var(--primary-color);
    border: 0.125rem solid var(--primary-color); /* 2px */
}

.btn-secondary:hover {
    background: rgba(0, 122, 255, 0.1);
}

.btn-back {
    background: var(--light-bg);
    color: var(--text-primary);
    border: 0.0625rem solid var(--border-color); /* 1px */
}

.btn-back:hover {
    background: #e5e5ea;
}

.btn-submit {
    background: var(--success-color);
    color: white;
}

.btn-submit:hover {
    background: #2d9c4b;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
}

/* 第三方登录 */
.social-login {
    margin-top: clamp(1.5rem, 6vw, 2rem);
    text-align: center;
}

.social-divider {
    display: flex;
    align-items: center;
    margin-bottom: clamp(1rem, 4vw, 1.5rem);
}

.social-divider::before,
.social-divider::after {
    content: "";
    flex: 1;
    height: 0.0625rem; /* 1px */
    background-color: var(--border-color);
}

.social-divider-text {
    padding: 0 1rem;
    font-size: clamp(0.75rem, 3vw, 0.875rem);
    color: var(--text-secondary);
}

.social-buttons {
    display: flex;
    justify-content: center;
    gap: clamp(1rem, 4vw, 1.5rem);
}

.social-btn {
    width: clamp(2.5rem, 10vw, 3rem);
    height: clamp(2.5rem, 10vw, 3rem);
    border-radius: 50%;
    background: var(--card-bg);
    border: 0.0625rem solid var(--border-color); /* 1px */
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.25rem;
    transition: all 0.2s ease;
}

.social-btn:hover {
    transform: translateY(-0.125rem); /* -2px */
    box-shadow: 0 0.25rem 0.75rem rgba(0, 0, 0, 0.1); /* 0 4px 12px */
}

.social-btn.wechat {
    color: #07C160;
}

.social-btn.qq {
    color: #12B7F5;
}

.social-btn.weibo {
    color: #E6162D;
}

/* 协议条款 */
.agreement {
    font-size: clamp(0.625rem, 2.5vw, 0.75rem);
    color: var(--text-secondary);
    text-align: center;
    margin-top: clamp(1.5rem, 6vw, 2rem);
    line-height: 1.6;
}

.agreement a {
    color: var(--primary-color);
    text-decoration: none;
}

.agreement a:hover {
    text-decoration: underline;
}

/* 错误提示 */
.error-message {
    color: var(--accent-color);
    font-size: clamp(0.625rem, 2.5vw, 0.75rem);
    margin-top: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.success-message {
    color: var(--success-color);
    font-size: clamp(0.625rem, 2.5vw, 0.75rem);
    margin-top: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* 成功页面 */
.success-page {
    text-align: center;
    padding: clamp(1rem, 4vw, 1.5rem) 0;
}

.success-icon {
    font-size: clamp(3rem, 12vw, 4rem);
    color: var(--success-color);
    margin-bottom: clamp(1rem, 4vw, 1.5rem);
}

.success-title {
    font-size: clamp(1.25rem, 5vw, 1.5rem);
    font-weight: 600;
    margin-bottom: clamp(0.75rem, 3vw, 1rem);
}

.success-description {
    font-size: clamp(0.875rem, 3.5vw, 1rem);
    color: var(--text-secondary);
    margin-bottom: clamp(1.5rem, 6vw, 2rem);
}

/* 加载动画 */
.loader {
    display: inline-block;
    width: 1.25rem;
    height: 1.25rem;
    border: 0.125rem solid rgba(255, 255, 255, 0.3); /* 2px */
    border-radius: 50%;
    border-top-color: white;
    animation: spin 0.8s linear infinite;
}

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

/* 针对 iPhone 6 的特殊修复 */
/* iPhone 6 屏幕宽度为 375px (23.4375rem) */
@media only screen 
and (max-device-width: 23.4375rem) /* 375px */
and (max-device-height: 41.6875rem) /* 667px */
and (-webkit-min-device-pixel-ratio: 2) {
    /* 修复容器溢出 */
    .container {
        width: 100%;
        padding: 0 0.75rem; /* 12px */
        overflow-x: hidden;
    }
    
    /* 修复头部 */
    .page-header {
        padding: 0.75rem 0; /* 12px */
        margin-bottom: 0.5rem; /* 8px */
    }
    
    .page-title {
        font-size: 1.125rem; /* 18px */
    }
    
    /* 修复主要内容区域 */
    .main-content {
        min-height: calc(100vh - 6.25rem); /* 100px */
        padding: 0.5rem 0; /* 8px */
    }
    
    /* 修复表单卡片 */
    .form-container {
        padding: 1rem;
        margin-bottom: 1rem;
        max-width: 100%;
    }
    .form-tab {
        padding: 0.3rem 0;
        font-size: 1.2rem;
        font-weight:bold;
    }
    
    /* 修复表单元素 */
    .form-group {
        margin-bottom: 0.75rem;
    }
    
    .form-label {
        font-size: 1rem;
        margin-bottom: 0.25rem;
    }
    
    .form-input {
        padding: 0.625rem 0.75rem;
        font-size: 0.875rem;
        border: 0.0625rem solid var(--border-color);
    }
    
    .input-icon {
        left: 0.5rem;
        font-size: 0.875rem;
    }
    
    .input-icon + .form-input {
        padding-left: 2rem;
    }
    
    .password-toggle {
        right: 0.5rem;
        font-size: 1.125rem;
    }
    
    /* 修复短信验证码 */
    .sms-group {
        gap: 0.5rem;
    }
    
    .sms-btn {
        padding: 0 0.75rem;
        font-size: 0.75rem;
        min-width: 6.25rem;
    }
    
    /* 修复按钮 */
    .btn {
        padding: 0.75rem 1rem;
        font-size: 0.875rem;
    }
    
    .form-actions {
        gap: 0.75rem;
        margin-top: 1.25rem;
    }
    
    /* 修复社交按钮 */
    .social-buttons {
        gap: 1rem;
    }
    
    .social-btn {
        width: 2.75rem;
        height: 2.75rem;
        font-size: 1.125rem;
    }
    
    /* 修复成功页面 */
    .success-icon {
        font-size: 3rem;
        margin-bottom: 1.25rem;
    }
    
    .success-title {
        font-size: 1.125rem;
    }
    
    .success-description {
        font-size: 0.875rem;
    }
}

/* iPhone 6 Plus 修复 */
@media only screen and (min-device-width: 25.875rem) and (max-device-width: 46rem) and (-webkit-min-device-pixel-ratio: 3) {
    .container {
        max-width: 25.875rem;
    }
}

/* 针对 iOS 10-12 的特殊修复 */
@supports (-webkit-touch-callout: none) and (not (translate: none)) {
    /* 修复不支持现代 CSS 的旧版 iOS */
    .form-input:focus {
        box-shadow: none;
        border-width: 0.125rem;
    }
    
    .btn:hover {
        transform: none;
    }
}