/* ===== CSS Variables ===== */
:root {
    --blue: #4285F4;
    --red: #EA4335;
    --yellow: #FBBC05;
    --green: #34A853;
    --dark: #202124;
    --dark2: #303134;
    --gray: #5F6368;
    --gray-light: #9AA0A6;
    --gray-bg: #F8F9FA;
    --white: #FFFFFF;
    --shadow: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: all 0.3s ease;
}

/* ===== Reset ===== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Google Sans', Roboto, 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
    color: var(--dark);
    line-height: 1.7;
    background: var(--white);
    overflow-x: hidden;
}
a { color: var(--blue); text-decoration: none; transition: var(--transition); }
a:hover { color: #1a73e8; }
img { max-width: 100%; display: block; }
ul { list-style: none; }

/* ===== Layout ===== */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.section { padding: 80px 0; }
.section-header { text-align: center; margin-bottom: 56px; }
.section-header h2 { font-size: 2rem; font-weight: 700; margin-bottom: 12px; color: var(--dark); }
.section-header p { font-size: 1.05rem; color: var(--gray); max-width: 700px; margin: 0 auto; }

/* ===== Badge ===== */
.badge {
    display: inline-block;
    background: linear-gradient(135deg, var(--blue), #1a73e8);
    color: var(--white);
    font-size: 0.8rem;
    font-weight: 600;
    padding: 4px 14px;
    border-radius: 20px;
    margin-bottom: 16px;
    letter-spacing: 0.5px;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    justify-content: center;
}
.btn-primary {
    background: var(--blue);
    color: var(--white);
    box-shadow: 0 2px 8px rgba(66,133,244,0.3);
}
.btn-primary:hover {
    background: #1a73e8;
    color: var(--white);
    box-shadow: 0 4px 16px rgba(66,133,244,0.4);
    transform: translateY(-2px);
}
.btn-outline {
    background: transparent;
    color: var(--blue);
    border: 2px solid var(--blue);
}
.btn-outline:hover {
    background: var(--blue);
    color: var(--white);
}
.btn-lg { padding: 16px 36px; font-size: 1.05rem; border-radius: var(--radius); }
.btn-block { width: 100%; }

/* ===== Header ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid transparent;
    transition: var(--transition);
}
.header.scrolled {
    border-bottom-color: #e8eaed;
    box-shadow: 0 1px 6px rgba(0,0,0,0.06);
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}
.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--dark);
}
.nav { display: flex; gap: 8px; }
.nav a {
    padding: 8px 16px;
    color: var(--gray);
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: 20px;
    transition: var(--transition);
}
.nav a:hover, .nav a.active {
    color: var(--blue);
    background: rgba(66,133,244,0.08);
}
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}
.menu-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--dark);
    border-radius: 2px;
    transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 120px 24px 80px;
    background: linear-gradient(135deg, #E8F0FE 0%, #F0F4FF 30%, #FFF 60%, #FEF7E0 100%);
    overflow: hidden;
}
.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(circle at 20% 30%, rgba(66,133,244,0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(234,67,53,0.06) 0%, transparent 40%),
        radial-gradient(circle at 60% 80%, rgba(52,168,83,0.06) 0%, transparent 40%),
        radial-gradient(circle at 30% 70%, rgba(251,188,5,0.06) 0%, transparent 40%);
    pointer-events: none;
}
.hero-content { position: relative; z-index: 1; max-width: 850px; }
.hero h1 {
    font-size: 2.8rem;
    font-weight: 800;
    line-height: 1.3;
    margin-bottom: 16px;
    background: linear-gradient(135deg, var(--blue), var(--dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.hero-subtitle {
    font-size: 1.15rem;
    color: var(--gray);
    margin-bottom: 12px;
    font-weight: 500;
}
.hero-desc {
    font-size: 1rem;
    color: var(--gray);
    line-height: 1.8;
    margin-bottom: 32px;
}
.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 20px;
}
.hero-meta {
    font-size: 0.85rem;
    color: var(--gray-light);
}

/* ===== Stats ===== */
.stats {
    background: var(--dark);
    padding: 48px 0;
}
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
    text-align: center;
}
.stat-number {
    font-size: 2.2rem;
    font-weight: 800;
    color: var(--blue);
    margin-bottom: 4px;
}
.stat-label {
    font-size: 0.9rem;
    color: var(--gray-light);
}

/* ===== Features ===== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}
.feature-card {
    background: var(--white);
    border: 1px solid #e8eaed;
    border-radius: var(--radius);
    padding: 32px;
    transition: var(--transition);
}
.feature-card:hover {
    border-color: var(--blue);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}
.feature-icon {
    width: 56px;
    height: 56px;
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}
.feature-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--dark);
}
.feature-card p {
    font-size: 0.92rem;
    color: var(--gray);
    line-height: 1.7;
    margin-bottom: 16px;
}
.feature-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}
.feature-tags li {
    padding: 4px 12px;
    background: var(--gray-bg);
    color: var(--gray);
    font-size: 0.8rem;
    border-radius: 16px;
    font-weight: 500;
}

/* ===== Security Section ===== */
.security-section { background: var(--gray-bg); }
.security-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}
.security-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 32px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}
.security-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}
.security-icon {
    font-size: 2rem;
    margin-bottom: 16px;
}
.security-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--dark);
}
.security-card p {
    font-size: 0.92rem;
    color: var(--gray);
    line-height: 1.7;
}

/* ===== Integration Section ===== */
.integration-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}
.integration-card {
    text-align: center;
    padding: 32px 20px;
    background: var(--white);
    border: 1px solid #e8eaed;
    border-radius: var(--radius);
    transition: var(--transition);
}
.integration-card:hover {
    border-color: var(--blue);
    box-shadow: var(--shadow);
    transform: translateY(-3px);
}
.integration-icon {
    font-size: 2.4rem;
    margin-bottom: 14px;
}
.integration-card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--dark);
}
.integration-card p {
    font-size: 0.88rem;
    color: var(--gray);
    line-height: 1.6;
}

/* ===== Platform Section ===== */
.platform-section { background: var(--gray-bg); }
.platform-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}
.platform-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 28px 20px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
}
.platform-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-6px);
}
.platform-icon { margin-bottom: 16px; }
.platform-card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--dark);
}
.platform-card p {
    font-size: 0.88rem;
    color: var(--gray);
    line-height: 1.6;
    margin-bottom: 12px;
    flex: 1;
}
.platform-version {
    display: block;
    font-size: 0.8rem;
    color: var(--gray-light);
    margin-bottom: 16px;
}
.platform-card .btn { width: 100%; }

/* ===== Advantages Section ===== */
.advantages-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.advantage-item {
    text-align: center;
    padding: 32px 20px;
}
.advantage-icon {
    font-size: 2.4rem;
    margin-bottom: 16px;
}
.advantage-item h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--dark);
}
.advantage-item p {
    font-size: 0.9rem;
    color: var(--gray);
    line-height: 1.7;
}

/* ===== Developer Section ===== */
.developer-section { background: var(--dark); color: var(--white); }
.developer-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: center;
}
.developer-text h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--white);
}
.developer-text .highlight { color: var(--blue); }
.developer-text p {
    color: var(--gray-light);
    margin-bottom: 24px;
    font-size: 1rem;
    line-height: 1.7;
}
.developer-features { list-style: none; }
.developer-features li {
    padding: 8px 0;
    color: #dadce0;
    font-size: 0.95rem;
}

/* DevTools Mockup */
.devtools-mockup {
    background: #1e1e1e;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: 0 8px 40px rgba(0,0,0,0.4);
}
.devtools-header {
    display: flex;
    gap: 0;
    background: #2d2d2d;
    padding: 0;
    border-bottom: 1px solid #404040;
}
.devtools-tab {
    padding: 10px 16px;
    font-size: 0.8rem;
    color: #999;
    cursor: pointer;
    border-bottom: 2px solid transparent;
}
.devtools-tab.active {
    color: var(--blue);
    border-bottom-color: var(--blue);
    background: #1e1e1e;
}
.devtools-body { padding: 16px; font-family: 'Consolas', 'Monaco', monospace; font-size: 0.82rem; }
.code-line { padding: 3px 0; color: #d4d4d4; }
.code-line.indent { padding-left: 20px; }
.code-line.indent2 { padding-left: 40px; }
.code-line.highlight-line { background: rgba(66,133,244,0.12); border-left: 2px solid var(--blue); padding-left: 38px; }
.tag { color: #569cd6; }
.attr { color: #9cdcfe; }
.val { color: #ce9178; }

/* ===== Download Section ===== */
.download-section { background: linear-gradient(135deg, #E8F0FE, #F0F4FF); }
.download-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}
.download-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 28px 20px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
}
.download-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}
.download-icon { margin-bottom: 16px; }
.download-card h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--dark);
}
.download-card p {
    font-size: 0.88rem;
    color: var(--gray);
    margin-bottom: 12px;
}
.download-info {
    display: block;
    font-size: 0.8rem;
    color: var(--gray-light);
    margin-bottom: 4px;
}
.download-info:last-of-type { margin-bottom: 16px; }
.download-card .btn { width: 100%; margin-top: auto; }

/* ===== FAQ Section ===== */
.faq-section { background: var(--gray-bg); }
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
    background: var(--white);
    border-radius: var(--radius-sm);
    margin-bottom: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
}
.faq-question {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: 18px 24px;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--dark);
    text-align: left;
    transition: var(--transition);
}
.faq-question:hover { color: var(--blue); }
.faq-arrow {
    flex-shrink: 0;
    transition: transform 0.3s ease;
    color: var(--gray-light);
}
.faq-item.active .faq-arrow { transform: rotate(180deg); color: var(--blue); }
.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.3s ease;
}
.faq-item.active .faq-answer {
    max-height: 500px;
    padding: 0 24px 18px;
}
.faq-answer p {
    font-size: 0.9rem;
    color: var(--gray);
    line-height: 1.8;
}

/* ===== SEO Section ===== */
.seo-section { background: var(--white); }
.seo-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}
.seo-card {
    background: var(--gray-bg);
    border-radius: var(--radius-sm);
    padding: 24px;
    transition: var(--transition);
}
.seo-card:hover {
    box-shadow: var(--shadow);
    transform: translateY(-2px);
}
.seo-card h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--dark);
}
.seo-card p {
    font-size: 0.85rem;
    color: var(--gray);
    line-height: 1.7;
}

/* ===== Footer ===== */
.footer {
    background: var(--dark);
    color: var(--gray-light);
    padding: 60px 0 30px;
}
.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
    margin-bottom: 40px;
}
.footer-col h4 {
    color: var(--white);
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 16px;
}
.footer-col a {
    display: block;
    color: var(--gray-light);
    font-size: 0.88rem;
    padding: 4px 0;
    transition: var(--transition);
}
.footer-col a:hover { color: var(--blue); }
.footer-bottom {
    border-top: 1px solid var(--dark2);
    padding-top: 24px;
    text-align: center;
}
.footer-seo p {
    font-size: 0.82rem;
    color: #5F6368;
    line-height: 1.8;
    max-width: 900px;
    margin: 0 auto 16px;
}
.footer-links {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin-bottom: 12px;
}
.footer-links a { color: var(--gray-light); font-size: 0.85rem; }
.footer-links a:hover { color: var(--blue); }
.copyright {
    font-size: 0.82rem;
    color: #5F6368;
}

/* ===== Back to Top ===== */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    background: var(--blue);
    color: var(--white);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 16px rgba(66,133,244,0.3);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: var(--transition);
    z-index: 999;
}
.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}
.back-to-top:hover {
    background: #1a73e8;
    box-shadow: 0 6px 24px rgba(66,133,244,0.4);
}

/* ===== Animations ===== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
    .features-grid,
    .security-grid { grid-template-columns: repeat(2, 1fr); }
    .platform-grid,
    .download-grid { grid-template-columns: repeat(2, 1fr); }
    .integration-grid { grid-template-columns: repeat(3, 1fr); }
    .advantages-grid { grid-template-columns: repeat(2, 1fr); }
    .seo-grid { grid-template-columns: repeat(2, 1fr); }
    .developer-content { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
    .nav {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 16px 24px;
        border-bottom: 1px solid #e8eaed;
        box-shadow: var(--shadow-lg);
    }
    .nav.active { display: flex; }
    .menu-toggle { display: flex; }
    .hero h1 { font-size: 2rem; }
    .hero-subtitle { font-size: 1rem; }
    .hero-desc { font-size: 0.9rem; }
    .hero-desc br { display: none; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
    .features-grid,
    .security-grid { grid-template-columns: 1fr; }
    .integration-grid { grid-template-columns: repeat(2, 1fr); }
    .platform-grid,
    .download-grid { grid-template-columns: 1fr; }
    .advantages-grid { grid-template-columns: 1fr; }
    .seo-grid { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
    .section { padding: 56px 0; }
    .section-header h2 { font-size: 1.5rem; }
    .section-header p { font-size: 0.92rem; }
    .developer-visual { display: none; }
}

@media (max-width: 480px) {
    .hero { padding: 100px 16px 60px; min-height: auto; }
    .hero h1 { font-size: 1.6rem; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .stat-number { font-size: 1.6rem; }
    .integration-grid { grid-template-columns: 1fr; }
    .hero-actions { flex-direction: column; align-items: center; }
    .btn-lg { width: 100%; justify-content: center; }
}