/* ==========================================================================
   基础重置与变量
   ========================================================================== */
:root {
    --primary-color: #1F69E0;
    --primary-hover: #1554b8;
    --text-main: rgba(13, 13, 13, 0.9);
    --text-regular: rgba(13, 13, 13, 0.66);
    --text-light: #7B7B7B;
    --bg-main: #FFFFFF;
    --bg-secondary: #F8FAFB;
    --bg-card: #EAEAEA;
    --border-color: #D6EDFF;
    --font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    --nav-height: 64px;
    --content-width: 1200px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-family: var(--font-family);
    color: var(--text-main);
    background-color: var(--bg-main);
    -webkit-font-smoothing: antialiased;
}

body {
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

ul {
    list-style: none;
}

.section-container {
    max-width: var(--content-width);
    margin: 0 auto;
    padding: 80px 24px;
}

/* ==========================================================================
   导航栏 (Navbar)
   ========================================================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: var(--nav-height);
    background-color: transparent;
    border-bottom: 1px solid transparent;
    transition: background-color 0.3s ease, border-color 0.3s ease;
    z-index: 1000;
    display: flex;
    justify-content: center;
}

/* 滚动离开首屏后才出现毛玻璃底，首屏保持沉浸透明 */
.navbar.scrolled {
    background-color: rgba(244, 247, 254, 0.8);
    backdrop-filter: blur(10px);
    border-bottom-color: rgba(31, 105, 224, 0.06);
}

.navbar-inner {
    width: 100%;
    max-width: var(--content-width);
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.navbar-left {
    display: flex;
    align-items: center;
    gap: 48px;
    flex: 1;
}

.navbar-right {
    display: flex;
    justify-content: flex-end;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-tabs {
    display: flex;
    gap: 32px;
}

.nav-tab {
    font-size: 14px;
    color: var(--text-regular);
    font-weight: 500;
    position: relative;
    padding: 8px 0;
}

.nav-tab:hover, .nav-tab.active {
    color: var(--text-main);
}

.nav-tab.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--text-main);
    border-radius: 2px;
}

.btn-login {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-main);
    padding: 6px 16px;
    border-radius: 6px;
    background-color: transparent;
}

.btn-login:hover {
    background-color: rgba(0, 0, 0, 0.05);
}

/* ==========================================================================
   首屏 (Hero)
   ========================================================================== */
.hero {
    position: relative;
    text-align: center;
    padding: 120px 24px 80px;
    background: linear-gradient(180deg, #F4F7FE 0%, #FFFFFF 100%);
    overflow: hidden;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.hero::before {
    content: '';
    position: absolute;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(31,105,224,0.15) 0%, rgba(31,105,224,0) 70%);
    top: -150px;
    left: -150px;
    border-radius: 50%;
    z-index: 1;
}

.hero::after {
    content: '';
    position: absolute;
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(107,207,244,0.12) 0%, rgba(107,207,244,0) 70%);
    bottom: -200px;
    right: -200px;
    border-radius: 50%;
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 32px;
}

.hero-logo-wrapper {
    margin-bottom: 16px;
    position: relative;
    display: inline-block;
}

.hero-logo {
    animation: none;
}

.hero-title {
    font-size: 56px;
    font-weight: 600;
    line-height: 1.2;
    letter-spacing: 0.02em;
    margin-bottom: 16px;
    color: var(--text-main);
}

.hero-subtitle {
    font-size: 24px;
    font-weight: 400;
    color: var(--text-main);
    letter-spacing: 0.02em;
}

.hero-actions {
    margin-top: 28px;
    display: flex;
    align-items: center;
    gap: 16px;
}

.btn-download {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 64px;
    background: #0D0D0D !important;
    color: #FFFFFF !important;
    font-size: 16px;
    font-weight: 600;
    border-radius: 12px;
    border: none;
    transition: background 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
}

.btn-download:hover {
    background: #1a1a1a !important;
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.28);
    color: #FFFFFF !important;
}

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

.btn-free-use {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 64px;
    background: #FFFFFF;
    color: var(--text-main);
    font-size: 16px;
    font-weight: 600;
    border-radius: 12px;
    border: none;
    transition: background 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
}

.btn-free-use:hover {
    background: #F8F8F8;
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.14);
}

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

.hero-platforms {
    margin-top: 48px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.platform-icons {
    display: flex;
    gap: 16px;
    flex-wrap: nowrap;
    justify-content: center;
    max-width: 1200px;
    width: 100%;
}

.platform-card {
    width: 260px;
    min-height: 90px;
    height: auto;
    background: #FFFFFF;
    border-radius: 16px;
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: flex-start;
    gap: 16px;
    padding: 24px 20px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.12);
    transition: transform 0.3s ease, box-shadow 0.3s ease, filter 0.3s ease, opacity 0.3s ease;
    cursor: pointer;
    box-sizing: border-box;
    flex-shrink: 0;
}

.platform-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 16px 32px rgba(0,0,0,0.16);
}

.platform-card.coming-soon {
    filter: grayscale(100%);
    opacity: 0.5;
    cursor: default;
    box-shadow: 0 4px 12px rgba(0,0,0,0.04);
}

.platform-card.coming-soon:hover {
    transform: none;
    box-shadow: 0 4px 12px rgba(0,0,0,0.04);
}

.platform-card.coming-soon .platform-desc {
    max-height: 60px;
    opacity: 1;
    margin-top: 6px;
}

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

.platform-content {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    text-align: left;
    flex: 1;
}

.platform-name {
    font-size: 18px;
    color: #000000;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 8px;
    line-height: 1.2;
}

.platform-badge {
    font-size: 10px;
    background: #1F69E0;
    color: #FFFFFF;
    padding: 2px 6px;
    border-radius: 4px;
    font-weight: 500;
    line-height: 1;
}

.platform-badge.recommend {
    background: #E5A953;
    color: #FFFFFF;
}

.platform-desc {
    font-size: 12px;
    color: #333333;
    line-height: 1.4;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, opacity 0.3s ease, margin-top 0.3s ease;
}

.platform-card:hover .platform-desc {
    max-height: 60px;
    opacity: 1;
    margin-top: 6px;
}

.macos-options {
    display: flex;
    flex-direction: row;
    gap: 8px;
    width: 100%;
}

.dl-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    padding: 4px 10px;
    background-color: #E8F0FE;
    color: #1F69E0;
    text-decoration: none;
    font-size: 11px;
    font-weight: 500;
    border-radius: 6px;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.dl-btn:hover {
    background-color: #D0E2FC;
    color: #1555B5;
    text-decoration: none;
}

/* ==========================================================================
   产品介绍 (Product)
   ========================================================================== */
.section-product {
    background-color: var(--bg-main);
    text-align: center;
}

.section-label {
    display: inline-block;
    font-size: 18px;
    font-weight: 600;
    color: #FFFFFF;
    background-color: #000000;
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 8px 16px;
    border-radius: 8px;
    transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.section-label.active {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.25);
}

.section-title {
    font-size: 42px;
    font-weight: 600;
    margin-bottom: 24px;
    transition: color 0.3s ease;
    cursor: pointer;
}

.section-desc {
    font-size: 18px;
    color: var(--text-regular);
    max-width: 700px;
    margin: 0 auto 64px;
}

.feature-showcase {
    display: flex;
    flex-direction: column;
    gap: 80px;
    align-items: center;
    max-width: 1000px;
    margin: 0 auto;
}

.feature-row {
    display: flex;
    align-items: center;
    gap: 64px;
    text-align: left;
    width: 100%;
    transition: all 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.feature-row.fade-in-up.visible {
    opacity: 0.4;
    filter: grayscale(60%);
    transform: scale(0.98);
}

.feature-row.fade-in-up.visible.active {
    opacity: 1;
    filter: grayscale(0%);
    transform: scale(1);
}

.feature-row:nth-child(even) {
    flex-direction: row-reverse;
}

.feature-text {
    flex: 1;
    padding: 24px;
}

.feature-text h3 {
    font-size: 28px;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-main);
}

.feature-num {
    color: var(--primary-color);
    font-weight: 700;
    font-size: 32px;
}

.feature-text p {
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-regular);
}

.feature-media {
    flex: 1.2;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 12px 32px rgba(0,0,0,0.08);
    background-color: var(--bg-card);
    display: flex;
    align-items: center;
    justify-content: center;
}

.feature-media video {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 16px;
}

/* ==========================================================================
   使用教程 (Tutorial)
   ========================================================================== */
.section-tutorial {
    background-color: var(--bg-secondary);
}

.tutorial-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin-top: 40px;
}

.tutorial-card {
    background-color: var(--bg-main);
    border-radius: 16px;
    padding: 32px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.02);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
    cursor: pointer;
}

.tutorial-card::before,
.tutorial-card::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    z-index: 0;
    filter: blur(16px);
    opacity: 0.5;
    transition: transform 0.8s cubic-bezier(0.25, 0.8, 0.25, 1),
                filter 0.8s cubic-bezier(0.25, 0.8, 0.25, 1),
                opacity 0.8s cubic-bezier(0.25, 0.8, 0.25, 1);
}

.tutorial-card:nth-child(1) {
    background-color: #FFFFFF;
}
.tutorial-card:nth-child(1)::before {
    width: 150px;
    height: 150px;
    background: radial-gradient(circle, rgba(107,207,244,0.15) 0%, rgba(107,207,244,0) 70%);
    top: -50px;
    right: -50px;
}
.tutorial-card:nth-child(1)::after {
    width: 100px;
    height: 100px;
    background: radial-gradient(circle, rgba(31,105,224,0.1) 0%, rgba(31,105,224,0) 70%);
    bottom: 20px;
    right: 10%;
}

.tutorial-card:nth-child(2) {
    background-color: #FFFFFF;
}
.tutorial-card:nth-child(2)::before {
    width: 180px;
    height: 180px;
    background: radial-gradient(circle, rgba(31,105,224,0.15) 0%, rgba(31,105,224,0) 70%);
    bottom: -60px;
    left: -40px;
}
.tutorial-card:nth-child(2)::after {
    width: 120px;
    height: 120px;
    background: radial-gradient(circle, rgba(107,207,244,0.12) 0%, rgba(107,207,244,0) 70%);
    top: -30px;
    right: -30px;
}

.tutorial-card:nth-child(3) {
    background-color: #FFFFFF;
}
.tutorial-card:nth-child(3)::before {
    width: 120px;
    height: 120px;
    background: radial-gradient(circle, rgba(46,204,113,0.15) 0%, rgba(46,204,113,0) 70%);
    top: 20px;
    right: -20px;
}
.tutorial-card:nth-child(3)::after {
    width: 140px;
    height: 140px;
    background: radial-gradient(circle, rgba(46,204,113,0.1) 0%, rgba(46,204,113,0) 70%);
    bottom: -40px;
    left: -20px;
}

.tutorial-card:nth-child(4) {
    background-color: #FFFFFF;
}
.tutorial-card:nth-child(4)::before {
    width: 160px;
    height: 160px;
    background: radial-gradient(circle, rgba(245,166,35,0.15) 0%, rgba(245,166,35,0) 70%);
    bottom: -40px;
    right: -40px;
}
.tutorial-card:nth-child(4)::after {
    width: 120px;
    height: 120px;
    background: radial-gradient(circle, rgba(245,166,35,0.1) 0%, rgba(245,166,35,0) 70%);
    top: -30px;
    left: -20px;
}

.tutorial-card-inner {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.tutorial-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 24px rgba(0,0,0,0.06);
}

.tutorial-card:hover::before {
    transform: scale(1.6) translate(-6px, 6px);
    filter: blur(8px);
    opacity: 0.9;
}
.tutorial-card:hover::after {
    transform: scale(1.4) translate(6px, -6px);
    filter: blur(6px);
    opacity: 0.85;
}

.tutorial-card h3 {
    font-size: 20px;
    margin-bottom: 16px;
}

.tutorial-card p {
    font-size: 14px;
    color: var(--text-regular);
    margin-bottom: 16px;
}

.tutorial-date {
    font-size: 12px !important;
    color: var(--text-light) !important;
}

.tutorial-more {
    font-size: 14px;
    color: var(--primary-color);
    font-weight: 500;
    margin-top: auto;
}

.tutorial-card-empty {
    background-color: transparent;
    border: 2px dashed #E0E0E0;
    align-items: center;
    justify-content: center;
    box-shadow: none;
}

.tutorial-card-empty:hover {
    transform: none;
    box-shadow: none;
    border-color: #CCC;
}

.empty-placeholder {
    text-align: center;
    color: var(--text-light);
}

.empty-placeholder svg {
    margin-bottom: 12px;
}

/* ==========================================================================
   官方资源 (Resources)
   ========================================================================== */
.section-resources {
    background-color: var(--bg-main);
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin-top: 40px;
}

.resource-card {
    display: flex;
    align-items: center;
    padding: 32px;
    background-color: var(--bg-secondary);
    border-radius: 16px;
    gap: 24px;
}

.resource-card:hover {
    background-color: #F0F4F8;
}

.resource-icon {
    width: 64px;
    height: 64px;
    background-color: #FFFFFF;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.04);
}

.resource-text {
    flex: 1;
}

.resource-text h3 {
    font-size: 18px;
    margin-bottom: 4px;
}

.resource-text p {
    font-size: 14px;
    color: var(--text-regular);
}

.resource-arrow {
    color: var(--text-light);
    transition: transform 0.3s ease;
}

.resource-card:hover .resource-arrow {
    transform: translateX(4px);
    color: var(--primary-color);
}

/* ==========================================================================
   底部 (Footer)
   ========================================================================== */
.site-footer {
    background-color: #F5F5F5;
    padding: 48px 24px 36px;
    font-size: 14px;
    color: var(--text-regular);
}

.footer-inner {
    max-width: var(--content-width);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 0;
}

.footer-top {
    padding-bottom: 28px;
}

.footer-section-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-main);
    margin-bottom: 16px;
}

.footer-report {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.footer-report-row {
    display: flex;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 4px;
    font-size: 13px;
    line-height: 1.6;
}

.footer-report-label {
    color: var(--text-regular);
}

.footer-report-value {
    color: var(--text-main);
    font-weight: 600;
    font-size: 14px;
}

.footer-report-link {
    color: var(--primary-color);
    font-weight: 500;
}

.footer-report-link:hover {
    text-decoration: underline;
}

.footer-col-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 18px;
    border: 1px solid #D6D6D6;
    border-radius: 6px;
    background-color: #FFFFFF;
    font-size: 13px;
    font-weight: 500;
    color: var(--text-main);
    width: fit-content;
    margin-top: 6px;
    transition: background-color 0.2s ease, border-color 0.2s ease;
    cursor: pointer;
}

.footer-col-btn:hover {
    background-color: #F0F0F0;
    border-color: #BFBFBF;
}

.footer-report-dropdown {
    position: relative;
    display: inline-block;
}

.footer-dropdown-menu {
    display: none;
    position: absolute;
    bottom: 100%;
    left: 0;
    margin-bottom: 8px;
    background-color: #FFFFFF;
    border: 1px solid #E0E0E0;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    min-width: 240px;
    z-index: 100;
    padding: 8px 0;
}

.footer-report-dropdown:hover .footer-dropdown-menu {
    display: block;
}

.footer-dropdown-menu a {
    display: block;
    padding: 8px 16px;
    color: var(--text-main);
    font-size: 13px;
    text-decoration: none;
    transition: background-color 0.2s ease, color 0.2s ease;
    white-space: nowrap;
}

.footer-dropdown-menu a:hover {
    background-color: #F5F5F5;
    color: var(--primary-color);
}

.footer-divider {
    height: 1px;
    background-color: #E0E0E0;
}

.footer-bottom {
    padding-top: 24px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-legal-row {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    font-size: 12px;
    color: var(--text-light);
    line-height: 1.8;
}

.footer-legal-link {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    color: var(--text-regular);
    transition: color 0.2s ease;
}

.footer-legal-link:hover {
    color: var(--primary-color);
}

.footer-legal-sep {
    color: #D6D6D6;
    user-select: none;
}

.footer-legal-text {
    color: var(--text-regular);
}

.footer-copyright {
    font-size: 12px;
    color: var(--text-light);
}

/* ==========================================================================
   教程弹窗 (Tutorial Modal)
   ========================================================================== */
body.modal-open {
    overflow: hidden;
}

.tutorial-modal {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 2000;
    align-items: center;
    justify-content: center;
}

.tutorial-modal.active {
    display: flex;
}

.tutorial-modal-overlay {
    position: absolute;
    inset: 0;
    background: rgba(0, 0, 0, 0.45);
    backdrop-filter: blur(4px);
}

.tutorial-modal-container {
    position: relative;
    width: 90%;
    max-width: 780px;
    max-height: 85vh;
    background: #FFFFFF;
    border-radius: 16px;
    box-shadow: 0 24px 64px rgba(0, 0, 0, 0.18);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    animation: modalSlideUp 0.3s ease;
}

@keyframes modalSlideUp {
    from { opacity: 0; transform: translateY(24px); }
    to   { opacity: 1; transform: translateY(0); }
}

.tutorial-modal-header {
    display: flex;
    justify-content: flex-end;
    padding: 16px 20px 0;
    flex-shrink: 0;
}

.tutorial-modal-close {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-light);
    padding: 4px;
    border-radius: 6px;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.tutorial-modal-close:hover {
    background-color: #F0F0F0;
    color: var(--text-main);
}

.tutorial-modal-body {
    padding: 8px 40px 40px;
    overflow-y: auto;
    line-height: 1.8;
    font-size: 15px;
    color: var(--text-main);
}

.tutorial-modal-body h1 {
    font-size: 26px;
    margin: 24px 0 16px;
}

.tutorial-modal-body h2 {
    font-size: 22px;
    margin: 28px 0 12px;
    padding-bottom: 8px;
    border-bottom: 1px solid #EAEAEA;
}

.tutorial-modal-body h3 {
    font-size: 18px;
    margin: 20px 0 8px;
}

.tutorial-modal-body p {
    margin: 8px 0;
}

.tutorial-modal-body img {
    max-width: 100%;
    border-radius: 8px;
    margin: 12px 0;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}

.tutorial-modal-body code {
    background: #F3F4F6;
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 13px;
}

.tutorial-modal-body pre {
    background: #F3F4F6;
    padding: 16px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 12px 0;
}

.tutorial-modal-body pre code {
    background: none;
    padding: 0;
}

.tutorial-modal-body ul,
.tutorial-modal-body ol {
    padding-left: 24px;
    margin: 8px 0;
}

.tutorial-modal-body li {
    margin: 4px 0;
    list-style: disc;
}

.tutorial-modal-body ol li {
    list-style: decimal;
}

.tutorial-modal-body blockquote {
    border-left: 3px solid var(--primary-color);
    padding: 8px 16px;
    margin: 12px 0;
    background: #F8FAFB;
    border-radius: 0 8px 8px 0;
    color: var(--text-regular);
}

.tutorial-modal-loading {
    text-align: center;
    padding: 48px 0;
    color: var(--text-light);
    font-size: 14px;
}

/* ==========================================================================
   动画与交互 (Animations)
   ========================================================================== */
.fade-in-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94), transform 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ==========================================================================
   响应式设计 (Responsive)
   ========================================================================== */
/* 平板 */
@media (max-width: 992px) {
    .section-container {
        padding: 64px 24px;
    }

    .hero-title {
        font-size: 40px;
    }

    .section-title {
        font-size: 36px;
    }

    .feature-showcase {
        gap: 64px;
    }

    .feature-row, .feature-row:nth-child(even) {
        flex-direction: column;
        gap: 32px;
        text-align: center;
    }

    .feature-text h3 {
        justify-content: center;
    }

    .tutorial-grid, .resource-grid {
        grid-template-columns: 1fr;
    }

    .footer-legal-row {
        flex-direction: column;
        gap: 4px;
    }

    .footer-legal-sep {
        display: none;
    }
}

/* 移动端 */
@media (max-width: 768px) {
    .section-container {
        padding: 56px 20px;
    }

    .navbar-left {
        gap: 24px;
    }

    .nav-tabs {
        display: none; /* 移动端隐藏导航，实际项目中可替换为汉堡菜单 */
    }

    .hero {
        padding: 100px 20px 64px;
    }

    .hero-content {
        gap: 24px;
    }

    .hero-title {
        font-size: 32px;
    }

    .hero-subtitle {
        font-size: 20px;
    }

    /* 按钮纵向堆叠、全宽，移动端层次更清晰且不会换行 */
    .hero-actions {
        flex-direction: column;
        width: 100%;
        max-width: 400px;
        gap: 12px;
    }

    .btn-download, .btn-free-use {
        width: 100%;
        padding: 14px 24px;
    }

    .section-title {
        font-size: 28px;
        margin-bottom: 16px;
    }

    .section-desc {
        font-size: 16px;
        margin-bottom: 48px;
    }

    .feature-showcase {
        gap: 56px;
    }

    .feature-text {
        padding: 0;
    }

    .feature-text h3 {
        font-size: 22px;
    }

    .feature-num {
        font-size: 26px;
    }

    .feature-text p {
        font-size: 15px;
    }

    .resource-card {
        padding: 24px 20px;
        gap: 16px;
    }

    .resource-icon {
        width: 52px;
        height: 52px;
    }

    .tutorial-modal-body {
        padding: 8px 20px 28px;
    }

    .platform-icons {
        flex-wrap: wrap;
        justify-content: center;
    }

    .platform-labels {
        display: none;
    }

    .footer-report-row {
        flex-direction: column;
        gap: 2px;
    }
}

/* 小屏手机 */
@media (max-width: 480px) {
    .hero-title {
        font-size: 28px;
    }

    .hero-subtitle {
        font-size: 18px;
    }

    .section-title {
        font-size: 24px;
    }
}

/* 下载按钮加载状态 */
.platform-card.dl-loading,
.dl-btn.dl-loading {
    opacity: 0.6;
    pointer-events: none;
    position: relative;
}
.platform-card.dl-loading::after,
.dl-btn.dl-loading::after {
    content: '';
    display: inline-block;
    width: 14px;
    height: 14px;
    margin-left: 6px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: dl-spin 0.6s linear infinite;
    vertical-align: middle;
}
@keyframes dl-spin {
    to { transform: rotate(360deg); }
}