/* 薯条聊天 Shutiao - 官方网站样式表 */
:root {
    --primary: #1a73e8;
    --primary-dark: #0d47a1;
    --primary-light: #e3f2fd;
    --accent: #00bcd4;
    --gradient-dark: linear-gradient(135deg, #0d1b2a 0%, #1b2838 50%, #162447 100%);
    --gradient-primary: linear-gradient(135deg, #1a73e8 0%, #0d47a1 100%);
    --text-dark: #1a1a2e;
    --text-light: #8892b0;
    --text-white: #ffffff;
    --bg-white: #ffffff;
    --bg-light: #f8f9fa;
    --bg-dark: #0d1b2a;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-full: 50%;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 30px rgba(26, 115, 232, 0.3);
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    --z-navbar: 1000;
}
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; overflow-x: hidden; }
body { font-family: var(--font-family); color: var(--text-dark); background: var(--bg-white); line-height: 1.6; overflow-x: hidden; }
a { text-decoration: none; color: inherit; transition: color var(--transition-fast); }
ul { list-style: none; }
img { max-width: 100%; height: auto; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 var(--spacing-md); }

/* 动画 */
@keyframes fadeInUp { from { opacity: 0; transform: translateY(30px); } to { opacity: 1; transform: translateY(0); } }
@keyframes fadeInLeft { from { opacity: 0; transform: translateX(-30px); } to { opacity: 1; transform: translateX(0); } }
@keyframes fadeInRight { from { opacity: 0; transform: translateX(30px); } to { opacity: 1; transform: translateX(0); } }
@keyframes pulse { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.05); } }
@keyframes float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-10px); } }
@keyframes scrollDown { 0%, 100% { transform: translateY(0); opacity: 1; } 50% { transform: translateY(8px); opacity: 0.5; } }
@keyframes particleFloat { 0%, 100% { transform: translateY(0) rotate(0deg); opacity: 0.3; } 50% { transform: translateY(-20px) rotate(180deg); opacity: 0.6; } }

/* 导航栏 */
.navbar { position: fixed; top: 0; left: 0; right: 0; z-index: var(--z-navbar); padding: var(--spacing-sm) 0; transition: all var(--transition-normal); }
.navbar.scrolled { background: rgba(255, 255, 255, 0.98); box-shadow: var(--shadow-sm); padding: var(--spacing-xs) 0; }
.nav-container { display: flex; align-items: center; justify-content: space-between; }
.nav-logo { display: flex; align-items: center; gap: var(--spacing-xs); }
.logo-img { width: 40px; height: 40px; border-radius: var(--radius-sm); }
.logo-text { font-size: 1.5rem; font-weight: 700; color: var(--text-white); letter-spacing: 0.05em; transition: color var(--transition-fast); }
.navbar.scrolled .logo-text { color: var(--text-dark); }
.nav-menu { display: flex; align-items: center; gap: var(--spacing-lg); }
.nav-link { font-size: 0.95rem; font-weight: 500; color: rgba(255, 255, 255, 0.9); padding: var(--spacing-xs) 0; position: relative; transition: color var(--transition-fast); }
.navbar.scrolled .nav-link { color: var(--text-dark); }
.nav-link::after { content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 2px; background: var(--primary); transition: width var(--transition-fast); }
.nav-link:hover::after, .nav-link.active::after { width: 100%; }
.nav-link:hover, .navbar.scrolled .nav-link:hover { color: var(--primary); }
.nav-link-cta { background: var(--gradient-primary); color: var(--text-white) !important; padding: var(--spacing-xs) var(--spacing-md) !important; border-radius: var(--radius-sm); }
.nav-link-cta::after { display: none; }
.nav-link-cta:hover { box-shadow: var(--shadow-glow); transform: translateY(-2px); }
.nav-toggle { display: none; width: 30px; height: 24px; position: relative; }
.hamburger, .hamburger::before, .hamburger::after { width: 100%; height: 3px; background: var(--text-white); border-radius: 2px; transition: all var(--transition-fast); }
.navbar.scrolled .hamburger, .navbar.scrolled .hamburger::before, .navbar.scrolled .hamburger::after { background: var(--text-dark); }
.hamburger { position: absolute; top: 50%; transform: translateY(-50%); }
.hamburger::before, .hamburger::after { content: ''; position: absolute; left: 0; }
.hamburger::before { top: -8px; }
.hamburger::after { bottom: -8px; }
.nav-toggle.active .hamburger { background: transparent; }
.nav-toggle.active .hamburger::before { top: 0; transform: rotate(45deg); }
.nav-toggle.active .hamburger::after { bottom: 0; transform: rotate(-45deg); }

/* Hero区域 */
.hero { min-height: 100vh; display: flex; align-items: center; position: relative; overflow: hidden; padding: var(--spacing-3xl) 0; }
.hero-bg { position: absolute; inset: 0; background: var(--gradient-dark); z-index: -1; }
.particles { position: absolute; inset: 0; overflow: hidden; }
.particles::before, .particles::after { content: ''; position: absolute; width: 400px; height: 400px; border-radius: var(--radius-full); background: radial-gradient(circle, rgba(26, 115, 232, 0.15) 0%, transparent 70%); animation: particleFloat 8s ease-in-out infinite; }
.particles::before { top: 10%; right: 10%; animation-delay: -2s; }
.particles::after { bottom: 10%; left: 5%; animation-delay: -4s; }
.geometric-lines { position: absolute; inset: 0; background-image: linear-gradient(rgba(26, 115, 232, 0.05) 1px, transparent 1px), linear-gradient(90deg, rgba(26, 115, 232, 0.05) 1px, transparent 1px); background-size: 50px 50px; }
.hero-container { display: grid; grid-template-columns: 1fr 1fr; gap: var(--spacing-2xl); align-items: center; padding-top: var(--spacing-2xl); }
.hero-content { animation: fadeInLeft 0.8s ease-out; }
.hero-title { font-size: clamp(2.5rem, 5vw, 3.5rem); font-weight: 800; color: var(--text-white); line-height: 1.2; margin-bottom: var(--spacing-md); letter-spacing: -0.02em; }
.hero-subtitle { font-size: 1.125rem; color: rgba(255, 255, 255, 0.8); line-height: 1.8; margin-bottom: var(--spacing-xl); max-width: 500px; }
.hero-buttons { display: flex; gap: var(--spacing-md); flex-wrap: wrap; }
.hero-visual { animation: fadeInRight 0.8s ease-out 0.2s both; }
.chat-mockup { background: rgba(255, 255, 255, 0.1); backdrop-filter: blur(20px); border-radius: var(--radius-lg); border: 1px solid rgba(255, 255, 255, 0.2); overflow: hidden; box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25); display: grid; grid-template-columns: 180px 1fr; grid-template-rows: auto 1fr; height: 400px; }
.mockup-header { grid-column: 1 / -1; background: rgba(0, 0, 0, 0.2); padding: var(--spacing-sm); display: flex; align-items: center; gap: var(--spacing-md); }
.mockup-dots { display: flex; gap: 6px; }
.mockup-dots span { width: 12px; height: 12px; border-radius: var(--radius-full); }
.mockup-dots span:first-child { background: #ff5f56; }
.mockup-dots span:nth-child(2) { background: #ffbd2e; }
.mockup-dots span:last-child { background: #27ca40; }
.mockup-title { color: rgba(255, 255, 255, 0.9); font-size: 0.875rem; }
.mockup-sidebar { background: rgba(0, 0, 0, 0.15); padding: var(--spacing-sm); border-right: 1px solid rgba(255, 255, 255, 0.1); }
.sidebar-item { display: flex; align-items: center; gap: var(--spacing-xs); padding: var(--spacing-xs); border-radius: var(--radius-sm); margin-bottom: var(--spacing-xs); cursor: pointer; transition: background var(--transition-fast); }
.sidebar-item:hover, .sidebar-item.active { background: rgba(255, 255, 255, 0.1); }
.avatar { width: 36px; height: 36px; background: var(--gradient-primary); border-radius: var(--radius-sm); display: flex; align-items: center; justify-content: center; color: var(--text-white); font-size: 0.875rem; font-weight: 600; }
.chat-info { display: flex; flex-direction: column; overflow: hidden; }
.chat-name { color: var(--text-white); font-size: 0.8rem; font-weight: 500; }
.chat-preview { color: rgba(255, 255, 255, 0.6); font-size: 0.7rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mockup-content { padding: var(--spacing-md); display: flex; flex-direction: column; gap: var(--spacing-sm); overflow: hidden; }
.message { max-width: 80%; padding: var(--spacing-xs) var(--spacing-sm); border-radius: var(--radius-md); display: flex; flex-direction: column; }
.message-received { background: rgba(255, 255, 255, 0.15); align-self: flex-start; }
.message-sent { background: var(--primary); align-self: flex-end; }
.message-text { color: var(--text-white); font-size: 0.85rem; }
.message-time { color: rgba(255, 255, 255, 0.5); font-size: 0.65rem; align-self: flex-end; margin-top: 4px; }
.scroll-indicator { position: absolute; bottom: var(--spacing-lg); left: 50%; transform: translateX(-50%); display: flex; flex-direction: column; align-items: center; gap: var(--spacing-xs); color: rgba(255, 255, 255, 0.6); font-size: 0.875rem; }
.scroll-arrow { width: 24px; height: 24px; border-right: 2px solid currentColor; border-bottom: 2px solid currentColor; transform: rotate(45deg); animation: scrollDown 2s ease-in-out infinite; }

/* 按钮 */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: var(--spacing-xs); padding: var(--spacing-sm) var(--spacing-lg); font-size: 1rem; font-weight: 600; border-radius: var(--radius-sm); transition: all var(--transition-normal); cursor: pointer; }
.btn-primary { background: var(--gradient-primary); color: var(--text-white); border: none; }
.btn-primary:hover { box-shadow: var(--shadow-glow); transform: translateY(-2px); }
.btn-secondary { background: transparent; color: var(--text-white); border: 2px solid rgba(255, 255, 255, 0.5); }
.btn-secondary:hover { background: rgba(255, 255, 255, 0.1); border-color: var(--text-white); }
.btn-download { background: var(--gradient-primary); color: var(--text-white); width: 100%; }
.btn-download:hover { box-shadow: var(--shadow-glow); transform: translateY(-2px); }
.btn-block { width: 100%; }

/* 语言切换 */
.lang-switch { display: flex; align-items: center; position: relative; }
.lang-btn { display: flex; align-items: center; justify-content: center; gap: 4px; padding: 4px 12px; border-radius: var(--radius-sm); background: rgba(255, 255, 255, 0.15); color: var(--text-white); font-size: 0.8rem; font-weight: 600; letter-spacing: 0.05em; transition: all var(--transition-fast); border: 1px solid rgba(255, 255, 255, 0.3); cursor: pointer; }
.lang-btn:hover { background: rgba(255, 255, 255, 0.25); }
.lang-arrow { transition: transform var(--transition-fast); flex-shrink: 0; }
.lang-btn[aria-expanded="true"] .lang-arrow { transform: rotate(180deg); }
.navbar.scrolled .lang-btn { background: var(--primary-light); color: var(--primary); border-color: var(--primary-light); }
.navbar.scrolled .lang-btn:hover { background: var(--primary); color: var(--text-white); }
.lang-dropdown { position: absolute; top: calc(100% + 6px); right: 0; min-width: 120px; background: var(--bg-white); border-radius: var(--radius-sm); box-shadow: var(--shadow-md); border: 1px solid rgba(0, 0, 0, 0.08); padding: 4px 0; opacity: 0; visibility: hidden; transform: translateY(-8px); transition: all var(--transition-fast); z-index: 100; list-style: none; }
.lang-dropdown.open { opacity: 1; visibility: visible; transform: translateY(0); }
.lang-dropdown li { margin: 0; padding: 0; }
.lang-option { display: block; width: 100%; padding: 8px 16px; font-size: 0.85rem; font-weight: 500; color: var(--text-dark); background: none; border: none; cursor: pointer; text-align: left; transition: background var(--transition-fast); font-family: var(--font-family); }
.lang-option:hover { background: var(--bg-light); }
.lang-option.active { color: var(--primary); font-weight: 600; }

/* 通用区块 */
.section-header { text-align: center; margin-bottom: var(--spacing-2xl); }
.section-tag { display: inline-block; padding: var(--spacing-xs) var(--spacing-md); background: var(--primary-light); color: var(--primary); font-size: 0.875rem; font-weight: 600; border-radius: var(--radius-full); margin-bottom: var(--spacing-md); }
.section-header.light .section-tag { background: rgba(255, 255, 255, 0.2); color: var(--text-white); }
.section-title { font-size: clamp(1.75rem, 4vw, 2.5rem); font-weight: 700; color: var(--text-dark); margin-bottom: var(--spacing-sm); letter-spacing: -0.02em; }
.section-header.light .section-title { color: var(--text-white); }
.section-desc { font-size: 1.125rem; color: var(--text-light); max-width: 600px; margin: 0 auto; }
.section-header.light .section-desc { color: rgba(255, 255, 255, 0.8); }

/* 产品介绍 */
.about { padding: var(--spacing-3xl) 0; background: var(--bg-light); overflow: hidden; }
.about-content { display: grid; grid-template-columns: 1fr 1fr; gap: var(--spacing-2xl); align-items: center; }
.product-showcase { position: relative; overflow: hidden; }
.showcase-screen { background: var(--bg-white); border-radius: var(--radius-lg); box-shadow: var(--shadow-lg); padding: var(--spacing-lg); position: relative; z-index: 2; }
.screen-header { display: flex; align-items: center; gap: var(--spacing-sm); margin-bottom: var(--spacing-md); padding-bottom: var(--spacing-sm); border-bottom: 1px solid var(--bg-light); }
.screen-header span { font-weight: 600; color: var(--text-dark); }
.screen-content { display: flex; flex-direction: column; gap: var(--spacing-sm); }
.feature-card-mini { display: flex; align-items: center; gap: var(--spacing-sm); padding: var(--spacing-sm); background: var(--bg-light); border-radius: var(--radius-sm); }
.feature-card-mini span { font-size: 0.875rem; color: var(--text-dark); }
.showcase-decoration { position: absolute; inset: 0; z-index: 1; }
.deco-circle { position: absolute; width: 200px; height: 200px; border-radius: var(--radius-full); background: var(--gradient-primary); opacity: 0.1; top: -50px; right: -50px; animation: pulse 4s ease-in-out infinite; }
.deco-dots { position: absolute; bottom: -20px; left: -20px; width: 100px; height: 100px; background-image: radial-gradient(circle, var(--primary) 2px, transparent 2px); background-size: 20px 20px; opacity: 0.3; }
.about-text h3 { font-size: 1.75rem; font-weight: 700; color: var(--text-dark); margin-bottom: var(--spacing-md); }
.about-text p { color: var(--text-light); margin-bottom: var(--spacing-md); line-height: 1.8; }
.about-features { margin-top: var(--spacing-lg); }
.about-feature-item { display: flex; gap: var(--spacing-md); margin-bottom: var(--spacing-md); }
.feature-icon { width: 48px; height: 48px; background: var(--primary-light); border-radius: var(--radius-sm); display: flex; align-items: center; justify-content: center; color: var(--primary); flex-shrink: 0; }
.feature-content h4 { font-size: 1rem; font-weight: 600; color: var(--text-dark); margin-bottom: 4px; }
.feature-content p { font-size: 0.875rem; color: var(--text-light); margin-bottom: 0; }

/* 功能特性 */
.features { padding: var(--spacing-3xl) 0; background: var(--bg-white); }
.features-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--spacing-lg); }
.feature-card { background: var(--bg-white); border-radius: var(--radius-md); padding: var(--spacing-xl); box-shadow: var(--shadow-sm); border: 1px solid rgba(0, 0, 0, 0.05); transition: all var(--transition-normal); }
.feature-card:hover { transform: translateY(-8px); box-shadow: var(--shadow-lg); border-color: var(--primary-light); }
.feature-card-icon { margin-bottom: var(--spacing-md); }
.feature-card-title { font-size: 1.25rem; font-weight: 600; color: var(--text-dark); margin-bottom: var(--spacing-sm); }
.feature-card-desc { font-size: 0.95rem; color: var(--text-light); line-height: 1.7; }

/* 客户案例 */
.clients { padding: var(--spacing-3xl) 0; background: var(--bg-white); }
.clients-logos { display: grid; grid-template-columns: repeat(6, 1fr); gap: var(--spacing-md); margin-bottom: var(--spacing-2xl); }
.client-logo { display: flex; align-items: center; justify-content: center; padding: var(--spacing-md); background: var(--bg-light); border-radius: var(--radius-md); transition: all var(--transition-normal); }
.client-logo:hover { background: var(--bg-white); box-shadow: var(--shadow-md); }
.logo-placeholder { font-size: 0.875rem; font-weight: 600; color: var(--text-light); text-align: center; }
.testimonials { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--spacing-lg); }
.testimonial-card { background: var(--bg-white); border-radius: var(--radius-md); padding: var(--spacing-xl); box-shadow: var(--shadow-sm); border: 1px solid rgba(0, 0, 0, 0.05); transition: all var(--transition-normal); }
.testimonial-card:hover { box-shadow: var(--shadow-md); }
.testimonial-content { margin-bottom: var(--spacing-md); }
.testimonial-content p { font-size: 1rem; color: var(--text-dark); line-height: 1.7; font-style: italic; }
.testimonial-content p::before { content: '"'; color: var(--primary); font-size: 1.5rem; }
.testimonial-author { display: flex; align-items: center; gap: var(--spacing-sm); }
.author-avatar { width: 48px; height: 48px; background: var(--gradient-primary); border-radius: var(--radius-full); display: flex; align-items: center; justify-content: center; color: var(--text-white); font-size: 1.25rem; font-weight: 600; }
.author-info { display: flex; flex-direction: column; }
.author-name { font-weight: 600; color: var(--text-dark); }
.author-title { font-size: 0.875rem; color: var(--text-light); }

/* 页脚 */
.footer { background: var(--bg-dark); padding: var(--spacing-2xl) 0 var(--spacing-lg); color: var(--text-white); }
.footer-content { display: grid; grid-template-columns: 1.5fr 2fr; gap: var(--spacing-2xl); margin-bottom: var(--spacing-2xl); }
.footer-brand { max-width: 300px; }
.footer-logo { display: flex; align-items: center; gap: var(--spacing-xs); margin-bottom: var(--spacing-md); }
.footer-logo img { width: 40px; height: 40px; border-radius: var(--radius-sm); }
.footer-logo span { font-size: 1.5rem; font-weight: 700; }
.footer-brand p { color: rgba(255, 255, 255, 0.7); font-size: 0.95rem; line-height: 1.7; margin-bottom: var(--spacing-md); }
.footer-social { display: flex; gap: var(--spacing-sm); }
.footer-social a { width: 40px; height: 40px; background: rgba(255, 255, 255, 0.1); border-radius: var(--radius-sm); display: flex; align-items: center; justify-content: center; color: var(--text-white); transition: all var(--transition-fast); }
.footer-social a:hover { background: var(--primary); }
.footer-links { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--spacing-lg); }
.footer-column h4 { font-size: 1rem; font-weight: 600; margin-bottom: var(--spacing-md); }
.footer-column ul li { margin-bottom: var(--spacing-xs); }
.footer-column a { color: rgba(255, 255, 255, 0.7); font-size: 0.9rem; transition: color var(--transition-fast); }
.footer-column a:hover { color: var(--primary); }
.footer-contact ul li { color: rgba(255, 255, 255, 0.7); font-size: 0.9rem; margin-bottom: var(--spacing-xs); }
.footer-contact ul li span { color: rgba(255, 255, 255, 0.7); }
.footer-bottom { text-align: center; padding-top: var(--spacing-lg); border-top: 1px solid rgba(255, 255, 255, 0.1); }
.footer-bottom p { color: rgba(255, 255, 255, 0.5); font-size: 0.875rem; margin-bottom: var(--spacing-xs); }
.footer-beian { display: flex; align-items: center; justify-content: center; gap: var(--spacing-sm); flex-wrap: wrap; }
.footer-beian a { color: rgba(255, 255, 255, 0.5); font-size: 0.875rem; transition: color var(--transition-fast); }
.footer-beian a:hover { color: var(--primary); }
.beian-divider { color: rgba(255, 255, 255, 0.3); }

/* 回到顶部 */
.back-to-top { position: fixed; bottom: var(--spacing-lg); right: var(--spacing-lg); width: 48px; height: 48px; background: var(--gradient-primary); border-radius: var(--radius-full); display: flex; align-items: center; justify-content: center; color: var(--text-white); box-shadow: var(--shadow-md); opacity: 0; visibility: hidden; transition: all var(--transition-normal); z-index: 999; }
.back-to-top.visible { opacity: 1; visibility: visible; }
.back-to-top:hover { transform: translateY(-4px); box-shadow: var(--shadow-glow); }

/* 响应式设计 */
@media (max-width: 1200px) {
    .clients-logos { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 992px) {
    .hero-container { grid-template-columns: 1fr; text-align: center; }
    .hero-subtitle { margin: 0 auto var(--spacing-xl); }
    .hero-buttons { justify-content: center; }
    .hero-visual { margin-top: var(--spacing-xl); }
    .chat-mockup { max-width: 500px; margin: 0 auto; }
    .about-content { grid-template-columns: 1fr; }
    .about-visual { order: 2; }
    .about-text { order: 1; }
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .testimonials { grid-template-columns: 1fr; }
    .footer-content { grid-template-columns: 1fr; }
    .footer-links { margin-top: var(--spacing-lg); }
}
@media (max-width: 768px) {
    .nav-toggle { display: block; z-index: 1001; }
    .nav-menu { position: fixed; top: 0; right: -100%; width: 240px; height: 100vh; background: var(--bg-white); flex-direction: column; align-items: stretch; padding: 72px 24px 32px; gap: 12px; transition: right var(--transition-normal); box-shadow: var(--shadow-lg); z-index: 1000; }
    .nav-menu.active { right: 0; }
    /* 移动端导航遮罩层 */
    .nav-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.4); z-index: 999; opacity: 0; visibility: hidden; pointer-events: none; transition: opacity 0.3s ease, visibility 0.3s ease; }
    .nav-overlay.active { opacity: 1; visibility: visible; pointer-events: auto; }
    /* 侧滑菜单内的链接深色（白色背景） */
    .nav-link { color: var(--text-dark) !important; font-size: 1rem; padding: 10px 0; border-bottom: 1px solid rgba(0,0,0,0.06); }
    .nav-link:hover, .nav-link.active { color: var(--primary) !important; }
    .nav-link-cta { margin-top: 8px; border-bottom: none; }
    .lang-switch { margin-top: 8px; width: 100%; }
    .lang-btn { background: var(--primary-light); color: var(--primary); border-color: var(--primary-light); width: 100%; justify-content: center; padding: 10px 16px; }
    .lang-btn:hover { background: var(--primary); color: var(--text-white); }
    /* Logo 默认白色（深色背景），滚动后深色（白色背景） */
    .navbar .logo-text { color: var(--text-white); }
    .navbar.scrolled .logo-text { color: var(--text-dark); }
    /* Hamburger 默认白色，滚动后深色 */
    .navbar .hamburger,
    .navbar .hamburger::before,
    .navbar .hamburger::after { background: var(--text-white); }
    .navbar.scrolled .hamburger,
    .navbar.scrolled .hamburger::before,
    .navbar.scrolled .hamburger::after { background: var(--text-dark); }
    /* Hamburger 激活时（X形态）深色，因为旁边是白色侧滑菜单 */
    .nav-toggle.active .hamburger { background: transparent; }
    .nav-toggle.active .hamburger::before,
    .nav-toggle.active .hamburger::after { background: var(--text-dark); }
    .features-grid { grid-template-columns: 1fr; }
    .clients-logos { grid-template-columns: repeat(2, 1fr); }
    .footer-links { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 576px) {
    html { font-size: 14px; }
    .chat-mockup { grid-template-columns: 1fr; height: auto; }
    .mockup-sidebar { display: none; }
    .clients-logos { grid-template-columns: 1fr; }
    .footer-links { grid-template-columns: 1fr; }
    .particles::before, .particles::after { width: 200px; height: 200px; }
    .deco-circle { top: -30px; right: -30px; width: 150px; height: 150px; }
    .deco-dots { bottom: -10px; left: -10px; width: 80px; height: 80px; }
}