/* 全局变量：模仿 Google Material / NotebookLM 配色 */
:root {
    --bg-color: #ffffff;
    --text-primary: #1f1f1f;
    --text-secondary: #444746;
    --accent-blue: #1a73e8;
    --border-color: #e0e3e7;
    --badge-bg: #000000;
    --badge-text: #ffffff;
    
    /* 渐变色 */
    --gradient-start: #a8c7fa;
    --gradient-mid: #d3e3fd;
    --gradient-end: #ffffff;
    
    /* 字体栈 */
    --font-family: "Google Sans", "Roboto", "Segoe UI", Arial, sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.5;
    overflow-x: hidden;
}

/* 顶部极光背景 */
.aurora-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 400px;
    background: linear-gradient(135deg, #e8f0fe 0%, #e2f6f3 50%, #ffffff 100%);
    opacity: 0.8;
    z-index: -1;
    mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
    -webkit-mask-image: linear-gradient(to bottom, black 0%, transparent 100%);
}

/* 导航栏 */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 32px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 20px;
    font-weight: 500;
    color: var(--text-primary);
}

.menu-icon {
    display: flex;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
}

.menu-icon .bar {
    width: 20px;
    height: 2px;
    background-color: var(--text-primary);
}

/* 主容器 */
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

/* 头部大标题 */
.hero {
    text-align: center;
    margin-top: 60px;
    margin-bottom: 60px;
}

.hero-title {
    font-size: 64px;
    line-height: 1.1;
    font-weight: 500;
    letter-spacing: -1px; /* 调整字间距 */
}

.hero-subtitle {
    margin-top: 12px;
    font-size: 20px;
    color: var(--text-secondary);
    font-weight: 400;
    letter-spacing: 0.5px;
}

.gradient-text {
    background: linear-gradient(90deg, #4285f4, #34a853, #7cb342);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-weight: 500;
}

/* 优势展示 */
.features {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 16px 24px;
    margin-top: 32px;
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #f8f9fa 0%, #ffffff 100%);
    border: 1px solid var(--border-color);
    padding: 10px 20px;
    border-radius: 50px;
    font-size: 15px;
    color: var(--text-secondary);
    transition: all 0.2s ease;
}

.feature-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    border-color: #c8ccd0;
}

.feature-icon {
    width: 20px;
    height: 20px;
    color: #34a853;
    flex-shrink: 0;
}

.feature-text {
    font-weight: 500;
}

/* 下载按钮组 */
.download-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
    margin-bottom: 100px;
}

.store-badge {
    display: flex;
    align-items: center;
    background-color: var(--badge-bg);
    color: var(--badge-text);
    padding: 8px 24px;
    border-radius: 12px;
    text-decoration: none;
    width: 260px;
    height: 64px;
    transition: transform 0.2s, opacity 0.2s;
}

.store-badge:hover {
    transform: translateY(-2px);
    opacity: 0.9;
}

.badge-icon {
    width: 32px;
    height: 32px;
    margin-right: 16px;
}

.badge-text {
    display: flex;
    flex-direction: column;
    justify-content: center;
    line-height: 1.1;
}

.badge-small {
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    opacity: 0.8; /* 增加一点透明度区分层级 */
    margin-bottom: 2px;
}

.badge-large {
    font-size: 18px; /* 中文稍大一点更清晰 */
    font-weight: 500; /* 中文不需要太粗 */
    letter-spacing: 1px;
}

/* FAQ 区域 */
.faq-section {
    margin-bottom: 100px;
}

.section-title {
    font-size: 32px;
    font-weight: 400;
    margin-bottom: 16px;
    letter-spacing: -0.5px;
}

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

.section-desc {
    color: var(--text-secondary);
    font-size: 16px;
    margin-bottom: 40px;
}

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

.accordion {
    border-top: 1px solid var(--border-color);
}

.accordion-item {
    border-bottom: 1px solid var(--border-color);
}

.accordion-header {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 0;
    background: none;
    border: none;
    font-size: 18px;
    color: var(--accent-blue);
    cursor: pointer;
    text-align: left;
    font-family: inherit;
}

.icon-chevron {
    width: 10px;
    height: 10px;
    border-right: 2px solid var(--accent-blue);
    border-bottom: 2px solid var(--accent-blue);
    transform: rotate(45deg);
    transition: transform 0.3s;
    margin-left: 12px;
}

.accordion-item.active .icon-chevron {
    transform: rotate(-135deg);
}

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    color: var(--text-secondary);
    font-size: 16px;
    line-height: 1.6;
}

.accordion-content p {
    padding-bottom: 24px;
}

/* 安全展示区域 */
.security-section {
    margin-bottom: 80px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.security-visual {
    position: relative;
    width: 240px;
    height: 240px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 20px;
}

.ring {
    position: absolute;
    border-radius: 50%;
    border: 1px solid #e8f0fe;
}

.ring-1 {
    width: 160px;
    height: 160px;
    border-color: #c2e7ff;
}

.ring-2 {
    width: 240px;
    height: 240px;
    border-color: #f0f4f8;
}

.lock-icon {
    width: 80px;
    height: 80px;
    background: #f8f9fa;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    z-index: 2;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.item-icon {
    position: absolute;
    width: 40px;
    height: 40px;
    background: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.item-icon.left {
    left: 20px;
    top: 50%;
}

.item-icon.right {
    right: 20px;
    top: 50%;
}

/* 页脚 */
.footer {
    border-top: 1px solid var(--border-color);
    padding: 32px 0;
    text-align: center;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    margin: 0 12px;
}

.footer-links a:hover {
    color: var(--accent-blue);
    text-decoration: underline;
}

/* 移动端适配 */
@media (max-width: 600px) {
    .container {
        padding: 16px;
    }
    
    .hero-title {
        font-size: 42px;
    }
    
    .download-group {
        gap: 16px;
    }
    
    .store-badge {
        width: 100%;
        max-width: 320px;
    }
    
    .accordion-header {
        font-size: 16px;
    }
}