/* ===== 全局重置与基础 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg-primary: #0b0e1a;
    --bg-card: rgba(20, 27, 43, 0.85);
    --bg-glass: rgba(11, 14, 26, 0.7);
    --border-color: rgba(31, 42, 63, 0.6);
    --text-primary: #e0e6f0;
    --text-secondary: #b0c4de;
    --text-heading: #ffffff;
    --accent-blue: #1a73e8;
    --accent-light: #4a9eff;
    --accent-gradient: linear-gradient(135deg, #1a73e8 0%, #0d47a1 100%);
    --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.4);
    --radius-card: 20px;
    --radius-btn: 40px;
    --transition: 0.35s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

a {
    color: var(--accent-light);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: #fff;
    text-decoration: underline;
}

/* ===== 滚动条 ===== */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-blue);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-light);
}

/* ===== 头部导航 ===== */
header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--bg-glass);
    backdrop-filter: blur(16px) saturate(180%);
    -webkit-backdrop-filter: blur(16px) saturate(180%);
    border-bottom: 1px solid var(--border-color);
    transition: background var(--transition);
}

.nav-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0.6rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
}

.logo {
    display: flex;
    align-items: center;
    transition: transform 0.3s ease;
}

.logo:hover {
    transform: scale(1.02);
}

.logo svg {
    filter: drop-shadow(0 2px 8px rgba(26, 115, 232, 0.3));
}

.nav-links {
    display: flex;
    gap: 2.2rem;
    list-style: none;
    align-items: center;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 0.4rem 0;
    position: relative;
    letter-spacing: 0.3px;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-gradient);
    transition: width var(--transition);
    border-radius: 2px;
}

.nav-links a:hover::after,
.nav-links a:focus-visible::after {
    width: 100%;
}

.nav-links a:hover {
    color: #fff;
    text-decoration: none;
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.4rem;
    z-index: 1001;
}

.mobile-menu-toggle span {
    display: block;
    width: 28px;
    height: 2.5px;
    background: var(--text-secondary);
    margin: 6px 0;
    transition: all 0.3s ease;
    border-radius: 2px;
}

.mobile-menu-toggle[aria-expanded="true"] span:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

.mobile-menu-toggle[aria-expanded="true"] span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0);
}

.mobile-menu-toggle[aria-expanded="true"] span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

/* ===== 主内容区 ===== */
main {
    max-width: 1280px;
    margin: 0 auto;
    padding: 2.5rem 2rem 4rem;
}

section {
    margin-bottom: 5rem;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.7s ease forwards;
}

section:nth-child(1) { animation-delay: 0.1s; }
section:nth-child(2) { animation-delay: 0.2s; }
section:nth-child(3) { animation-delay: 0.3s; }
section:nth-child(4) { animation-delay: 0.4s; }
section:nth-child(5) { animation-delay: 0.5s; }
section:nth-child(6) { animation-delay: 0.6s; }
section:nth-child(7) { animation-delay: 0.7s; }
section:nth-child(8) { animation-delay: 0.8s; }
section:nth-child(9) { animation-delay: 0.9s; }

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== 标题样式 ===== */
h1 {
    font-size: 3.2rem;
    font-weight: 800;
    margin-bottom: 1rem;
    color: var(--text-heading);
    line-height: 1.2;
    background: linear-gradient(135deg, #ffffff 0%, #4a9eff 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

h2 {
    font-size: 2.2rem;
    font-weight: 700;
    margin-bottom: 1.2rem;
    color: var(--text-heading);
    border-left: 5px solid var(--accent-blue);
    padding-left: 1.2rem;
    position: relative;
}

h2::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 5px;
    background: var(--accent-gradient);
    border-radius: 3px;
}

h3 {
    font-size: 1.35rem;
    font-weight: 600;
    margin-bottom: 0.6rem;
    color: #d0d8e8;
}

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-size: 1.05rem;
}

/* ===== Hero 区域 ===== */
.hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 3rem;
    flex-wrap: wrap;
    padding: 4rem 0 2rem;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -20%;
    width: 80%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(26, 115, 232, 0.12) 0%, transparent 70%);
    pointer-events: none;
}

.hero-content {
    flex: 1 1 450px;
    position: relative;
    z-index: 1;
}

.hero-content p {
    font-size: 1.15rem;
    line-height: 1.8;
    max-width: 600px;
}

.hero-visual {
    flex: 1 1 350px;
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-visual svg {
    width: 100%;
    max-width: 420px;
    height: auto;
    filter: drop-shadow(0 0 60px rgba(26, 115, 232, 0.25));
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-15px); }
}

.hero-actions {
    display: flex;
    gap: 1.2rem;
    flex-wrap: wrap;
    margin-top: 1.5rem;
}

/* ===== 按钮 ===== */
.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.9rem 2.5rem;
    border-radius: var(--radius-btn);
    font-weight: 600;
    font-size: 1rem;
    transition: all var(--transition);
    cursor: pointer;
    border: none;
    position: relative;
    overflow: hidden;
    letter-spacing: 0.5px;
}

.btn-primary {
    background: var(--accent-gradient);
    color: #fff;
    box-shadow: 0 4px 20px rgba(26, 115, 232, 0.35);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(26, 115, 232, 0.5);
    text-decoration: none;
    color: #fff;
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: transparent;
    border: 2px solid var(--accent-light);
    color: var(--accent-light);
}

.btn-secondary:hover {
    background: var(--accent-light);
    color: #0b0e1a;
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(74, 158, 255, 0.3);
    text-decoration: none;
}

/* ===== 卡片网格 ===== */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.card {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--radius-card);
    padding: 2rem 1.8rem;
    border: 1px solid var(--border-color);
    transition: all var(--transition);
    box-shadow: var(--shadow-card);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent-gradient);
    opacity: 0;
    transition: opacity var(--transition);
}

.card:hover {
    border-color: var(--accent-light);
    transform: translateY(-8px);
    box-shadow: 0 16px 48px rgba(0, 0, 0, 0.5);
}

.card:hover::before {
    opacity: 1;
}

.card h3 {
    font-size: 1.4rem;
    margin-bottom: 0.8rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.card p {
    font-size: 0.95rem;
    margin-bottom: 0;
}

/* ===== 下载区域 ===== */
.download-buttons {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
    margin: 2rem 0;
}

.download-buttons .btn-primary {
    padding: 1rem 3rem;
    font-size: 1.1rem;
}

/* ===== FAQ 手风琴 ===== */
.faq-list details {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border-radius: 16px;
    padding: 1.2rem 1.8rem;
    margin-bottom: 1rem;
    border: 1px solid var(--border-color);
    transition: all var(--transition);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
}

.faq-list details:hover {
    border-color: var(--accent-light);
}

.faq-list details[open] {
    border-color: var(--accent-blue);
    box-shadow: 0 8px 32px rgba(26, 115, 232, 0.15);
}

.faq-list summary {
    font-weight: 600;
    cursor: pointer;
    color: #d0d8e8;
    font-size: 1.05rem;
    padding: 0.2rem 0;
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: color var(--transition);
}

.faq-list summary::-webkit-details-marker {
    display: none;
}

.faq-list summary::after {
    content: '+';
    font-size: 1.5rem;
    font-weight: 300;
    color: var(--accent-light);
    transition: transform 0.3s ease;
}

.faq-list details[open] summary::after {
    content: '−';
    transform: rotate(180deg);
}

.faq-list details[open] summary {
    color: #fff;
}

.faq-list p {
    margin-top: 1rem;
    padding-top: 0.8rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.98rem;
}

/* ===== 有序列表 ===== */
ol {
    padding-left: 1.5rem;
    counter-reset: step;
}

ol li {
    margin-bottom: 1rem;
    padding: 0.8rem 1.2rem;
    background: var(--bg-card);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: all var(--transition);
    list-style: none;
    counter-increment: step;
    position: relative;
    padding-left: 3.5rem;
}

ol li::before {
    content: counter(step);
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    width: 28px;
    height: 28px;
    background: var(--accent-gradient);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.85rem;
}

ol li:hover {
    border-color: var(--accent-light);
    transform: translateX(5px);
}

ol li strong {
    color: var(--accent-light);
}

/* ===== 地址与联系 ===== */
address p {
    margin-bottom: 0.5rem;
    font-style: normal;
}

address a {
    color: var(--accent-light);
    font-weight: 500;
}

address a:hover {
    color: #fff;
}

/* ===== 页脚 ===== */
footer {
    background: #0a0d18;
    border-top: 1px solid var(--border-color);
    padding: 2.5rem 2rem;
    text-align: center;
    position: relative;
}

footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: var(--accent-gradient);
    opacity: 0.3;
}

.footer-content {
    max-width: 1280px;
    margin: 0 auto;
}

footer p {
    color: #7a8ba8;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

footer nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 2.5rem;
    margin-top: 1.2rem;
    flex-wrap: wrap;
}

footer nav a {
    color: #7a8ba8;
    font-size: 0.9rem;
    position: relative;
    padding-bottom: 2px;
}

footer nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--accent-light);
    transition: width var(--transition);
}

footer nav a:hover::after {
    width: 100%;
}

footer nav a:hover {
    color: var(--accent-light);
    text-decoration: none;
}

/* ===== 返回顶部按钮 ===== */
#back-to-top {
    position: fixed;
    bottom: 2.5rem;
    right: 2.5rem;
    background: var(--accent-gradient);
    color: #fff;
    border: none;
    border-radius: 50%;
    width: 52px;
    height: 52px;
    font-size: 1.6rem;
    cursor: pointer;
    box-shadow: 0 6px 24px rgba(26, 115, 232, 0.4);
    transition: all var(--transition);
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transform: scale(0.8);
    pointer-events: none;
}

#back-to-top.show {
    opacity: 1;
    transform: scale(1);
    pointer-events: auto;
}

#back-to-top:hover {
    transform: translateY(-4px) scale(1.05);
    box-shadow: 0 10px 35px rgba(26, 115, 232, 0.55);
}

#back-to-top:active {
    transform: scale(0.95);
}

/* ===== 响应式设计 ===== */
@media (max-width: 1024px) {
    main {
        padding: 2rem 1.5rem;
    }
    
    h1 {
        font-size: 2.6rem;
    }
    
    h2 {
        font-size: 1.9rem;
    }
    
    .hero {
        padding: 2rem 0;
    }
}

@media (max-width: 768px) {
    .nav-container {
        padding: 0.5rem 1.2rem;
    }
    
    .nav-links {
        display: none;
        flex-direction: column;
        width: 100%;
        background: var(--bg-glass);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        padding: 1.2rem 0;
        border-top: 1px solid var(--border-color);
        gap: 0.2rem;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
    }
    
    .nav-links.open {
        display: flex;
    }
    
    .nav-links li {
        width: 100%;
    }
    
    .nav-links a {
        display: block;
        padding: 0.8rem 1.5rem;
        font-size: 1.05rem;
        border-left: 3px solid transparent;
    }
    
    .nav-links a:hover {
        border-left-color: var(--accent-blue);
        background: rgba(26, 115, 232, 0.08);
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    h1 {
        font-size: 2rem;
        line-height: 1.3;
    }
    
    h2 {
        font-size: 1.6rem;
        padding-left: 1rem;
    }
    
    .hero {
        flex-direction: column;
        text-align: center;
        padding: 1.5rem 0;
    }
    
    .hero-content p {
        margin-left: auto;
        margin-right: auto;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .hero-visual svg {
        max-width: 300px;
    }
    
    .card-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .card {
        padding: 1.5rem;
    }
    
    .download-buttons {
        justify-content: center;
    }
    
    .faq-list details {
        padding: 1rem 1.2rem;
    }
    
    ol li {
        padding-left: 3rem;
        padding: 0.7rem 1rem 0.7rem 3rem;
    }
    
    footer {
        padding: 1.8rem 1.2rem;
    }
    
    footer nav ul {
        gap: 1.5rem;
    }
    
    #back-to-top {
        bottom: 1.5rem;
        right: 1.5rem;
        width: 44px;
        height: 44px;
        font-size: 1.3rem;
    }
}

@media (max-width: 480px) {
    main {
        padding: 1.5rem 1rem;
    }
    
    h1 {
        font-size: 1.7rem;
    }
    
    h2 {
        font-size: 1.4rem;
    }
    
    .btn-primary,
    .btn-secondary {
        padding: 0.7rem 1.8rem;
        font-size: 0.9rem;
    }
    
    .hero-visual svg {
        max-width: 240px;
    }
    
    .card {
        padding: 1.2rem;
    }
    
    .faq-list details {
        padding: 0.8rem 1rem;
    }
}

/* ===== 暗色模式（默认） ===== */
@media (prefers-color-scheme: light) {
    :root {
        --bg-primary: #f0f4fa;
        --bg-card: rgba(255, 255, 255, 0.85);
        --bg-glass: rgba(255, 255, 255, 0.75);
        --border-color: rgba(180, 190, 210, 0.5);
        --text-primary: #1a1f2e;
        --text-secondary: #2a3a5e;
        --text-heading: #0b0e1a;
        --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.08);
    }
    
    body {
        background: var(--bg-primary);
        color: var(--text-primary);
    }
    
    header {
        background: var(--bg-glass);
        border-bottom-color: var(--border-color);
    }
    
    .nav-links a {
        color: var(--text-secondary);
    }
    
    .nav-links a:hover {
        color: var(--accent-blue);
    }
    
    h1 {
        background: linear-gradient(135deg, #0b0e1a 0%, #1a73e8 100%);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        background-clip: text;
    }
    
    h2 {
        color: var(--text-heading);
    }
    
    h3 {
        color: #1a1f2e;
    }
    
    p {
        color: var(--text-secondary);
    }
    
    .card {
        background: var(--bg-card);
        border-color: var(--border-color);
    }
    
    .card:hover {
        border-color: var(--accent-blue);
    }
    
    .faq-list details {
        background: var(--bg-card);
        border-color: var(--border-color);
    }
    
    .faq-list summary {
        color: #1a1f2e;
    }
    
    .faq-list details[open] summary {
        color: var(--accent-blue);
    }
    
    .faq-list p {
        border-top-color: var(--border-color);
    }
    
    ol li {
        background: var(--bg-card);
        border-color: var(--border-color);
    }
    
    footer {
        background: #e8ecf2;
        border-top-color: var(--border-color);
    }
    
    footer p {
        color: #5a6a7e;
    }
    
    footer nav a {
        color: #5a6a7e;
    }
    
    #back-to-top {
        background: var(--accent-gradient);
        color: #fff;
    }
}

/* ===== 减少动画偏好 ===== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* ===== 无障碍焦点样式 ===== */
a:focus-visible,
button:focus-visible,
summary:focus-visible {
    outline: 3px solid var(--accent-light);
    outline-offset: 3px;
    border-radius: 4px;
}

/* ===== 打印样式 ===== */
@media print {
    header,
    #back-to-top,
    .hero-visual {
        display: none;
    }
    
    body {
        background: #fff;
        color: #000;
    }
    
    .card,
    .faq-list details,
    ol li {
        border: 1px solid #ccc;
        box-shadow: none;
        background: #fff;
    }
}