:root {
    --primary-color: #0066b8;
    --dark-color: #1e1e1e;
    --light-color: #f5f5f5;
    /* 使用rem单位 */
    --brand-margin-left: 6.25rem; /* 约20px */
    --nav-btn-gap: 30.5rem; /* 约40px */
}

html {
    font-size: 16px; /* 设置基准字体大小 */
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: #333;
    line-height: 1.6;
    /* 移除或调整padding-top，这是造成空白的主要原因 */
    padding-top: 0; /* 改为0，或根据实际导航栏高度调整 */
}

/* 语言切换按钮样式 */
.language-switcher {
    position: absolute;
    right: 0.9375rem; /* 15px -> 0.9375rem */
    top: 50%;
    transform: translateY(-50%);
}

.toggle-btn {
    background-color: transparent;
    border: 1px solid #dee2e6;
    color: #495057;
    padding: 0.375rem 0.75rem; /* 6px 12px -> 0.375rem 0.75rem */
    text-align: center;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    font-size: 0.875rem;
    cursor: pointer;
    border-radius: 0.25rem; /* 4px -> 0.25rem */
    transition: all 0.3s;
}

.toggle-btn:hover {
    background-color: #f8f9fa;
    border-color: #adb5bd;
}

/* 导航栏样式 - 移除边框 */
.navbar {
    background-color: white;
    /* 移除box-shadow，去掉底边边框效果 */
    box-shadow: none;
    padding: 0.5rem 0;
    position: fixed;
    top: 0; /* 确保导航栏紧贴顶部 */
    left: 0;
    right: 0;
    z-index: 1030; /* 确保导航栏在最上层 */
    /* 移除可能的多余边距 */
    margin: 0;
    /* 添加一个轻微的底部边框作为可选替代，如果需要的话 */
    /* border-bottom: 1px solid rgba(0, 0, 0, 0.05); */
}

/* 修复固定定位导航栏导致的内容遮挡问题 */
body {
    /* 如果导航栏高度已知，可以设置相应的padding-top */
    /* padding-top: [导航栏高度]; */
}

/* 或者使用更精确的方法计算导航栏高度 */
.navbar {
    height: auto; /* 或设置为固定高度，如 4rem */
}

/* 计算导航栏高度并设置body的padding-top */
@media (min-width: 768px) {
    body {
        padding-top: 4rem; /* 根据实际导航栏高度调整 */
    }
}

.navbar-brand {
    font-weight: 600;
    margin-right: 2rem;
    margin-left: var(--brand-margin-left);
}

.nav-link {
    color: #333 !important;
    font-weight: 500;
    transition: color 0.2s;
    padding: 0.5rem 0.75rem !important;
}

.nav-link:hover {
    color: var(--primary-color) !important;
}

.navbar-brand {
    display: flex;
    align-items: center;
}

.navbar-logo {
    transition: transform 0.3s ease;
}

.navbar-logo:hover {
    transform: scale(1.1);
}

.brand-text {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.25rem;
}

/* 导航链接容器 */
.nav-links-container {
    margin-left: 0.5rem;
    margin-right: var(--nav-btn-gap);
}

/* 响应式调整 */
@media (max-width: 1200px) {
    :root {
        --brand-margin-left: 1rem;
        --nav-btn-gap: 2rem;
    }
}

@media (max-width: 992px) {
    :root {
        --brand-margin-left: 0.75rem;
        --nav-btn-gap: 1.5rem;
    }
}

@media (max-width: 768px) {
    :root {
        --brand-margin-left: 0.5rem;
        --nav-btn-gap: 1rem;
    }
    
    .language-switcher {
        position: static;
        transform: none;
        margin-top: 0.625rem;
        text-align: center;
    }
    
    .navbar .d-flex {
        flex-direction: row;
        justify-content: flex-start;
        width: 100%;
        margin-top: 0.625rem;
    }
    
    .nav-links-container {
        margin-left: 0;
        margin-right: 0;
    }
    
    .navbar-brand {
        margin-left: 0;
    }
    
    /* 移动端调整body的padding-top */
    body {
        padding-top: 3.5rem; /* 移动端导航栏可能更高 */
    }
}

@media (max-width: 576px) {
    html {
        font-size: 14px;
    }
    
    .nav-link {
        padding: 0.5rem 0.5rem !important;
    }
    
    body {
        padding-top: 3rem; /* 超小屏幕进一步调整 */
    }
}

/* 修复Bootstrap可能带来的默认样式 */
.container {
    padding-left: 0.9375rem;
    padding-right: 0.9375rem;
}

/* 确保导航栏容器没有额外边距 */
.navbar > .container {
    margin-left: auto;
    margin-right: auto;
    padding-left: 0.9375rem;
    padding-right: 0.9375rem;
}

/* 开始区域 */
.start-section {
    background-color: var(--primary-color);
    color: white;
    padding: 80px 0;
}

/* 英雄区域 */
.hero {
    background-color: var(--primary-color);
    color: white;
    padding: 80px 0 100px;
    text-align: center;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 300;
    margin-bottom: 20px;
}

.hero p {
    font-size: 1.5rem;
    font-weight: 300;
    margin-bottom: 30px;
}

/* 按钮基础样式 */
.btn-download {
    background-color: #28a745;
    color: white;
    padding: 12px 30px;
    font-size: 1.2rem;
    border-radius: 2px;
    font-weight: 600;
    margin: 0 10px;
    border: none;
    position: relative;
    overflow: hidden;
    transition: all 0.4s ease;
    z-index: 1;
}

/* 按钮悬停效果 */
.btn-download:hover {
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* 按钮外围边框 */
.btn-download::before {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    border: 2px solid transparent;
    border-radius: 4px;
    opacity: 0;
    transition: opacity 0.3s ease;
    z-index: -1;
}

.btn-download:hover::before {
    opacity: 1;
    border-color: #6f42c1;
}

/* 紫色渐变背景 */
.btn-download::after {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    width: 0;
    height: 100%;
    background: linear-gradient(90deg, #6f42c1, #8e63d2, #6f42c1);
    transition: all 0.1s ease;
    z-index: -1;
    transform: translateX(-50%);
}

.btn-download:hover::after {
    width: 100%;
}

.btn-download:hover {
    outline: 2px solid #007bff; /* 边框颜色 */
    outline-offset: 4px; /* 边框与按钮的间距 */
    transition: outline 0.3s ease; /* 平滑过渡效果 */
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border: 1px solid white;
    padding: 12px 30px;
    font-size: 1.2rem;
    border-radius: 2px;
    font-weight: 600;
}

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

/* 功能区域 */
.feature-section {
    padding: 80px 0;
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.feature-card {
    padding: 30px;
    text-align: center;
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-card h3 {
    margin-bottom: 15px;
    font-weight: 600;
}

/* 深色区域 */
.dark-section {
    background-color: var(--dark-color);
    color: white;
    padding: 80px 0;
}

/* 用户评价logo */
.testimonial-logo {
    height: 40px;
    margin: 20px;
    opacity: 0.7;
    transition: opacity 0.3s;
}

.testimonial-logo:hover {
    opacity: 1;
}

/* 页脚 */
footer {
    background-color: #f5f5f5;
    padding: 40px 0;
    font-size: 0.9rem;
}

/* 弹出框样式 */
.modal-content {
    border: none;
    border-radius: 0;
}

.modal-header {
    border-bottom: none;
    padding-bottom: 0;
}

.modal-title {
    font-weight: 600;
}

.list-group-item {
    border-left: none;
    border-right: none;
}

.list-group-item:first-child {
    border-top: none;
}

/* 响应式调整 */
@media (max-width: 768px) {
    .language-switcher {
        position: static;
        transform: none;
        margin-top: 10px;
        text-align: center;
    }
    
    .navbar .d-flex {
        flex-direction: row;
        justify-content: flex-start;
        width: 100%;
        margin-top: 10px;
    }
    
    .navbar-logo {
        width: 20px;
        height: 20px;
    }
    
    .brand-text {
        font-size: 1.1rem;
    }
    
    .nav-links-container {
        margin-left: 0; /* 移动端不需要左边距 */
        margin-right: 0; /* 移动端不需要右边距 */
    }
    
    /* 移动端调整品牌logo位置 */
    .navbar-brand {
        margin-left: 0;
    }
}