/* ============================================
   纸飞机电脑版 - 主样式表 (pc.css)
   版本: 2.0 | 设计理念: 桌面·高效·沉浸
   ============================================ */

/* ---------- 设计令牌 (品牌统一) ---------- */
:root {
    --primary-color: #24A1DE;
    --primary-dark: #1a7faf;
    --primary-light: #e8f6fd;
    --dark-color: #1a1a2e;
    --text-color: #4A4A4A;
    --text-muted: #7a7a8a;
    --light-bg: #F4F6F9;
    --card-bg: #ffffff;
    --border-color: #E2E8F0;
    --border-light: #f0f2f5;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.10);
    --shadow-primary: 0 8px 24px rgba(36, 161, 222, 0.18);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;
    --transition-fast: 0.18s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    --content-max-width: 1000px;
    --nav-max-width: 1200px;
}

/* ---------- 全局重置 ---------- */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    font-size: 16px;
}

body {
    font-family: var(--font-stack);
    color: var(--text-color);
    line-height: 1.8;
    background-color: #ffffff;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 3px;
    border-radius: 4px;
}

/* ---------- 导航栏 ---------- */
header {
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.92);
    z-index: 1000;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition-smooth);
}

.nav-container {
    max-width: var(--nav-max-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 24px;
    gap: 20px;
}

.logo a {
    font-size: 20px;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 9px;
    letter-spacing: -0.3px;
    transition: opacity var(--transition-fast);
    white-space: nowrap;
}

.logo a:hover {
    opacity: 0.82;
}

.logo img {
    width: 32px;
    height: 32px;
    flex-shrink: 0;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 8px;
    align-items: center;
    flex-wrap: wrap;
}

.nav-links a {
    text-decoration: none;
    color: var(--dark-color);
    font-weight: 500;
    font-size: 15px;
    padding: 8px 16px;
    border-radius: 20px;
    transition: all var(--transition-fast);
    position: relative;
    white-space: nowrap;
}

.nav-links a:hover {
    color: var(--primary-color);
    background-color: var(--primary-light);
}

.nav-links a.active {
    color: #ffffff;
    background-color: var(--primary-color);
    font-weight: 600;
    box-shadow: var(--shadow-primary);
}

/* ---------- 面包屑 ---------- */
.breadcrumb {
    max-width: var(--nav-max-width);
    margin: 12px auto 0;
    padding: 0 24px;
    font-size: 13px;
    color: #999;
    display: flex;
    align-items: center;
    gap: 6px;
}

.breadcrumb a {
    color: #777;
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.breadcrumb span {
    color: #555;
    font-weight: 500;
}

/* ---------- PC Hero 区域 ---------- */
.pc-hero {
    max-width: var(--nav-max-width);
    margin: 30px auto 40px;
    padding: 0 24px;
    display: flex;
    align-items: center;
    gap: 40px;
    flex-wrap: wrap;
}

.pc-hero-content {
    flex: 1 1 400px;
}

.pc-hero-content h1 {
    font-size: 36px;
    font-weight: 800;
    color: var(--dark-color);
    margin-bottom: 16px;
    letter-spacing: -0.6px;
    background: linear-gradient(135deg, #1a1a2e 0%, #24A1DE 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-text {
    font-size: 16px;
    color: #6b7280;
    line-height: 1.8;
    margin-bottom: 24px;
}

.hero-actions {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
}

.btn-hero {
    display: inline-block;
    background: var(--primary-color);
    color: #fff;
    padding: 13px 28px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 700;
    font-size: 15px;
    box-shadow: 0 6px 20px rgba(36, 161, 222, 0.3);
    transition: all var(--transition-smooth);
    white-space: nowrap;
}

.btn-hero:hover {
    background: var(--primary-dark);
    box-shadow: 0 10px 30px rgba(36, 161, 222, 0.4);
    transform: translateY(-2px);
}

.btn-hero-secondary {
    display: inline-block;
    background: #fff;
    color: var(--primary-color);
    padding: 13px 28px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 700;
    font-size: 15px;
    border: 1.5px solid var(--primary-color);
    transition: all var(--transition-smooth);
    white-space: nowrap;
}

.btn-hero-secondary:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* 模拟窗口视觉效果 */
.pc-hero-visual {
    flex: 1 1 400px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.mockup-window {
    background: #ffffff;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg), 0 0 0 1px var(--border-color);
    overflow: hidden;
    width: 100%;
    max-width: 420px;
    transition: transform var(--transition-smooth);
}

.mockup-window:hover {
    transform: translateY(-4px);
    box-shadow: 0 24px 56px rgba(0, 0, 0, 0.12), 0 0 0 1px #cbd5e1;
}

.mockup-titlebar {
    background: #f1f3f5;
    padding: 12px 16px;
    display: flex;
    align-items: center;
    gap: 8px;
    border-bottom: 1px solid var(--border-color);
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    flex-shrink: 0;
}

.dot.red { background: #ff5f57; }
.dot.yellow { background: #febc2e; }
.dot.green { background: #28c840; }

.title-text {
    margin-left: 8px;
    font-size: 12px;
    color: #888;
    font-weight: 500;
}

.mockup-body {
    display: flex;
    height: 280px;
}

.mockup-sidebar {
    width: 90px;
    background: #f8fafc;
    border-right: 1px solid var(--border-light);
    padding: 14px 10px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    align-items: center;
}

.mockup-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: #d0e7f5;
    margin-bottom: 6px;
}

.mockup-line {
    width: 100%;
    height: 8px;
    background: #e2e8f0;
    border-radius: 4px;
}

.mockup-line.short {
    width: 60%;
    align-self: flex-start;
}

.mockup-chat {
    flex: 1;
    padding: 14px 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    justify-content: flex-end;
    background: #ffffff;
}

.mockup-bubble {
    height: 24px;
    border-radius: 10px;
    background: #e8f0fe;
    width: 65%;
}

.mockup-bubble.right {
    background: #24A1DE;
    align-self: flex-end;
    width: 50%;
}

.mockup-bubble.short {
    width: 40%;
}

.mockup-input {
    height: 28px;
    background: #f1f3f5;
    border-radius: 14px;
    margin-top: 6px;
    width: 100%;
}

/* ---------- 通用区块标题 ---------- */
.section-title {
    text-align: center;
    font-size: 28px;
    font-weight: 800;
    color: var(--dark-color);
    margin-bottom: 36px;
    letter-spacing: -0.4px;
    position: relative;
    padding-bottom: 16px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 3px;
    background: var(--primary-color);
    border-radius: 3px;
}

/* ---------- PC 下载卡片网格 ---------- */
.pc-downloads {
    max-width: var(--nav-max-width);
    margin: 50px auto 60px;
    padding: 0 24px;
}

.pc-card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.pc-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px 24px;
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: 16px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-smooth);
    position: relative;
    overflow: hidden;
}

.pc-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-color);
    opacity: 0;
    transition: opacity var(--transition-smooth);
}

.pc-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: #cbd5e1;
}

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

.pc-card-icon {
    display: flex;
    justify-content: center;
}

.pc-card-icon img {
    width: 48px;
    height: 48px;
}

.pc-card h3 {
    font-size: 20px;
    color: var(--dark-color);
    font-weight: 700;
}

.pc-card-desc {
    font-size: 14px;
    color: #6b7280;
    line-height: 1.7;
    flex: 1;
}

.pc-card-meta {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
    font-size: 12px;
    color: #999;
}

.pc-card-meta li {
    background: #f8fafc;
    padding: 4px 12px;
    border-radius: 20px;
    border: 1px solid var(--border-light);
    white-space: nowrap;
}

.pc-card-btns {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.btn-primary {
    display: block;
    background: var(--primary-color);
    color: #fff;
    padding: 12px 20px;
    border-radius: 25px;
    text-decoration: none;
    font-weight: 600;
    font-size: 14px;
    transition: all var(--transition-smooth);
    box-shadow: 0 4px 12px rgba(36, 161, 222, 0.2);
}

.btn-primary:hover {
    background: var(--primary-dark);
    box-shadow: 0 8px 22px rgba(36, 161, 222, 0.35);
    transform: translateY(-1px);
}

.btn-outline {
    display: block;
    background: #fff;
    color: #555;
    padding: 10px 16px;
    border-radius: 20px;
    text-decoration: none;
    font-weight: 500;
    font-size: 13px;
    border: 1px solid #ddd;
    transition: all var(--transition-smooth);
}

.btn-outline:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    background: #f8fafc;
}

/* ---------- 桌面端优势网格 ---------- */
.pc-features {
    max-width: var(--nav-max-width);
    margin: 0 auto 60px;
    padding: 0 24px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 20px;
}

.feature-item {
    background: #f8fafc;
    border-radius: var(--radius-md);
    padding: 24px 20px;
    border: 1px solid var(--border-light);
    transition: all var(--transition-smooth);
    text-align: center;
}

.feature-item:hover {
    background: #ffffff;
    box-shadow: var(--shadow-md);
    border-color: #d0ddf0;
    transform: translateY(-3px);
}

.feature-icon {
    font-size: 36px;
    display: block;
    margin-bottom: 12px;
}

.feature-item h4 {
    font-size: 17px;
    color: var(--dark-color);
    margin-bottom: 8px;
    font-weight: 700;
}

.feature-item p {
    font-size: 14px;
    color: #666;
    line-height: 1.7;
}

/* ---------- 安装步骤时间轴 ---------- */
.install-steps {
    max-width: 700px;
    margin: 0 auto 60px;
    padding: 0 24px;
}

.steps-timeline {
    position: relative;
    padding-left: 40px;
    border-left: 2px dashed var(--border-color);
    margin-left: 20px;
}

.timeline-item {
    position: relative;
    margin-bottom: 32px;
    padding-left: 24px;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-marker {
    position: absolute;
    left: -55px;
    top: 0;
    width: 36px;
    height: 36px;
    background: var(--primary-color);
    color: #fff;
    font-weight: 800;
    font-size: 16px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(36, 161, 222, 0.25);
    z-index: 2;
}

.timeline-content {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 18px 20px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-smooth);
}

.timeline-content:hover {
    box-shadow: var(--shadow-md);
    border-color: #cbd5e1;
}

.timeline-content h4 {
    font-size: 17px;
    color: var(--dark-color);
    margin-bottom: 6px;
    font-weight: 700;
}

.timeline-content p {
    font-size: 14px;
    color: #666;
    line-height: 1.7;
    margin: 0;
}

/* ---------- FAQ 卡片网格 ---------- */
.pc-faq {
    max-width: var(--nav-max-width);
    margin: 0 auto 60px;
    padding: 0 24px;
}

.faq-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

.faq-card {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 22px 20px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-smooth);
}

.faq-card:hover {
    box-shadow: var(--shadow-md);
    border-color: #cbd5e1;
    transform: translateY(-2px);
}

.faq-card h4 {
    font-size: 16px;
    color: var(--dark-color);
    margin-bottom: 10px;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 6px;
}

.faq-card p {
    font-size: 14px;
    color: #666;
    line-height: 1.7;
    margin: 0;
}

/* ---------- CTA 横幅 ---------- */
.cta-banner {
    max-width: 800px;
    margin: 0 auto 50px;
    padding: 32px 24px;
    background: linear-gradient(135deg, #f0f8fd, #e8f4fb);
    border-radius: var(--radius-lg);
    text-align: center;
    border: 1px solid #d0e5f3;
}

.cta-banner p {
    font-size: 17px;
    color: var(--dark-color);
    margin-bottom: 18px;
    font-weight: 500;
}

.cta-banner .btn-hero {
    display: inline-block;
}

/* ---------- 页脚 ---------- */
footer {
    background-color: var(--dark-color);
    color: #b0b0b8;
    padding: 44px 24px 28px;
    font-size: 14px;
    border-top: 3px solid var(--primary-color);
    margin-top: 30px;
}

.footer-container {
    max-width: var(--nav-max-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 36px;
}

.footer-info {
    flex: 1.3;
    min-width: 260px;
}

.footer-info h4,
.footer-links h4 {
    color: #e8e8ec;
    margin-bottom: 14px;
    font-size: 16px;
    font-weight: 700;
    letter-spacing: -0.2px;
    position: relative;
    padding-bottom: 10px;
}

.footer-info h4::after,
.footer-links h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 28px;
    height: 2px;
    background: var(--primary-color);
    border-radius: 2px;
}

.footer-links {
    flex: 1;
    min-width: 180px;
    display: flex;
    flex-direction: column;
    gap: 9px;
}

.footer-links a {
    color: #b0b0b8;
    text-decoration: none;
    font-size: 13px;
    transition: all var(--transition-fast);
    padding: 2px 0;
    display: inline-block;
    width: fit-content;
}

.footer-links a:hover {
    color: #ffffff;
    padding-left: 6px;
}

.copyright {
    width: 100%;
    text-align: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 12px;
    color: #777;
    letter-spacing: 0.3px;
}

/* ---------- 响应式设计 ---------- */
@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        gap: 10px;
        padding: 10px 16px;
    }
    .nav-links {
        gap: 4px;
        justify-content: center;
    }
    .nav-links a {
        font-size: 13px;
        padding: 6px 12px;
    }
    .logo a {
        font-size: 18px;
    }

    .pc-hero {
        flex-direction: column;
        gap: 24px;
    }
    .pc-hero-content h1 {
        font-size: 26px;
    }
    .hero-actions {
        flex-direction: column;
        align-items: flex-start;
    }

    .mockup-window {
        max-width: 100%;
    }

    .section-title {
        font-size: 22px;
    }

    .pc-card-grid {
        grid-template-columns: 1fr;
    }

    .steps-timeline {
        padding-left: 30px;
        margin-left: 10px;
    }
    .timeline-marker {
        left: -43px;
        width: 28px;
        height: 28px;
        font-size: 14px;
    }

    .faq-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .pc-card-meta {
        gap: 8px;
    }
    .pc-card-meta li {
        font-size: 11px;
        padding: 3px 10px;
    }

    .feature-item {
        text-align: left;
    }
}

/* ---------- 动画 ---------- */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(18px); }
    to { opacity: 1; transform: translateY(0); }
}

.pc-card {
    animation: fadeInUp 0.5s ease backwards;
}
.pc-card:nth-child(1) { animation-delay: 0.05s; }
.pc-card:nth-child(2) { animation-delay: 0.1s; }
.pc-card:nth-child(3) { animation-delay: 0.15s; }

.timeline-item {
    animation: fadeInUp 0.5s ease backwards;
}
.timeline-item:nth-child(1) { animation-delay: 0.1s; }
.timeline-item:nth-child(2) { animation-delay: 0.2s; }
.timeline-item:nth-child(3) { animation-delay: 0.3s; }

/* 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;
    }
}