/* 全局重置和基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #ff6b6b;
    --secondary-color: #4ecdc4;
    --text-dark: #2d3436;
    --text-light: #636e72;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #dfe6e9;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --max-width: 1200px;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
    overflow-x: hidden;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* 头部导航样式 */
.header {
    background-color: var(--bg-white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
}

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

.logo {
    font-size: 1.25rem;
    color: var(--primary-color);
    font-weight: 700;
    line-height: 1.4;
}

.logo strong {
    font-size: inherit;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
    font-size: 0.95rem;
}

.nav-menu a:hover {
    color: var(--primary-color);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--text-dark);
    transition: all 0.3s ease;
}

/* 主要内容区域 */
main {
    min-height: calc(100vh - 200px);
}

/* 英雄区域 */
.hero-section {
    padding: 3rem 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
}

.hero-content h1 {
    font-size: 2rem;
    margin-bottom: 1rem;
    font-weight: 700;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.hero-content h2 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    font-weight: 600;
    opacity: 0.95;
}

.lead {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    line-height: 1.8;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    padding: 0 1rem;
}

.hero-image {
    margin-top: 2rem;
}

.hero-image img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
    width: 100%;
    max-width: 600px;
}

/* 特点区域 */
.features-section {
    padding: 4rem 0;
    background-color: var(--bg-light);
}

.features-section h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-dark);
    font-weight: 700;
}

.features-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.feature-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

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

.feature-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
    font-weight: 600;
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.8;
    font-size: 1rem;
}

/* 下载区域 */
.download-section {
    padding: 4rem 0;
    background-color: var(--bg-white);
}

.download-section h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-dark);
    font-weight: 700;
}

.download-content {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    align-items: center;
}

.download-text {
    flex: 1;
}

.download-text h3 {
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
    font-weight: 600;
}

.download-text p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 1.5rem;
    font-size: 1.05rem;
}

.download-benefits {
    list-style: none;
    padding-left: 0;
}

.download-benefits li {
    padding: 0.75rem 0;
    padding-left: 2rem;
    position: relative;
    color: var(--text-dark);
    font-size: 1rem;
    line-height: 1.6;
}

.download-benefits li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: bold;
    font-size: 1.2rem;
}

.download-image {
    flex: 1;
    width: 100%;
}

.download-image img {
    width: 100%;
    max-width: 500px;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

/* 阅读步骤区域 */
.reading-section {
    padding: 4rem 0;
    background-color: var(--bg-light);
}

.reading-section h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-dark);
    font-weight: 700;
}

.reading-steps {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.step-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    position: relative;
    transition: transform 0.3s ease;
}

.step-card:hover {
    transform: translateY(-3px);
}

.step-number {
    display: inline-block;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-radius: 50%;
    text-align: center;
    line-height: 50px;
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 1.5rem;
}

.step-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
    font-weight: 600;
}

.step-card p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 1.5rem;
    font-size: 1rem;
}

.step-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: 8px;
}

/* FAQ区域 */
.faq-section {
    padding: 4rem 0;
    background-color: var(--bg-white);
}

.faq-section h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-dark);
    font-weight: 700;
}

.faq-list {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.faq-item {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.faq-item h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
    font-weight: 600;
}

.faq-item p {
    color: var(--text-light);
    line-height: 1.8;
    font-size: 1rem;
}

/* 内容区域 */
.content-section {
    padding: 4rem 0;
    background-color: var(--bg-light);
}

.content-section h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-dark);
    font-weight: 700;
}

.content-text {
    max-width: 900px;
    margin: 0 auto 2rem;
}

.content-text p {
    margin-bottom: 1.5rem;
    color: var(--text-dark);
    line-height: 1.8;
    font-size: 1.05rem;
    text-align: justify;
}

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

.content-image img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 700px;
}

/* 页脚 */
.footer {
    background-color: var(--text-dark);
    color: white;
    padding: 2.5rem 0;
    text-align: center;
}

.footer p {
    margin-bottom: 0.75rem;
    font-size: 0.95rem;
    line-height: 1.6;
}

.footer-note {
    font-size: 0.85rem;
    opacity: 0.8;
    margin-bottom: 0;
}

/* 图片优化 */
img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* 响应式设计 - 平板 */
@media (min-width: 768px) {
    .logo {
        font-size: 1.5rem;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }

    .hero-content h2 {
        font-size: 1.75rem;
    }

    .lead {
        font-size: 1.2rem;
    }

    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .download-content {
        flex-direction: row;
        align-items: flex-start;
    }

    .reading-steps {
        grid-template-columns: repeat(2, 1fr);
    }

    .faq-list {
        grid-template-columns: repeat(2, 1fr);
    }

    .nav-menu {
        gap: 2.5rem;
    }
}

/* 响应式设计 - 桌面 */
@media (min-width: 1024px) {
    .container {
        padding: 0 40px;
    }

    .hero-section {
        padding: 5rem 0;
    }

    .hero-content h1 {
        font-size: 3rem;
    }

    .hero-content h2 {
        font-size: 2rem;
    }

    .lead {
        font-size: 1.3rem;
    }

    .features-grid {
        grid-template-columns: repeat(4, 1fr);
    }

    .reading-steps {
        grid-template-columns: repeat(4, 1fr);
    }

    .features-section,
    .download-section,
    .reading-section,
    .faq-section,
    .content-section {
        padding: 5rem 0;
    }
}

/* 移动端菜单 */
@media (max-width: 767px) {
    .menu-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--bg-white);
        width: 100%;
        text-align: center;
        transition: left 0.3s ease;
        box-shadow: var(--shadow);
        padding: 2rem 0;
        gap: 1rem;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-menu li {
        width: 100%;
    }

    .nav-menu a {
        display: block;
        padding: 1rem;
        width: 100%;
    }

    .hero-section {
        padding: 2rem 0;
    }

    .hero-content h1 {
        font-size: 1.75rem;
    }

    .hero-content h2 {
        font-size: 1.25rem;
    }

    .lead {
        font-size: 1rem;
        padding: 0 0.5rem;
    }

    .features-section,
    .download-section,
    .reading-section,
    .faq-section,
    .content-section {
        padding: 2.5rem 0;
    }

    .features-section h2,
    .download-section h2,
    .reading-section h2,
    .faq-section h2,
    .content-section h2 {
        font-size: 1.75rem;
        margin-bottom: 2rem;
    }

    .feature-card,
    .step-card,
    .faq-item {
        padding: 1.5rem;
    }

    .content-text p {
        font-size: 1rem;
        text-align: left;
    }
}

/* 性能优化 - 减少重绘和重排 */
.feature-card,
.step-card,
.faq-item {
    will-change: transform;
}

/* 可访问性改进 */
a:focus,
button:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* 打印样式 */
@media print {
    .header,
    .footer,
    .menu-toggle {
        display: none;
    }
}