:root {
    --primary: #0078D7; /* Windows/Trustworthy blue */
    --primary-hover: #005A9E;
    --text-dark: #202124;
    --text-gray: #5F6368;
    --bg-light: #F8F9FA;
    --border: #DADCE0;
    --radius: 4px; /* Sharper corners for software feel */
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Segoe UI", "Microsoft YaHei", sans-serif;
}

body {
    color: var(--text-dark);
    line-height: 1.6;
    background: #fff;
}

a {
    text-decoration: none;
    color: inherit;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navbar */
.navbar {
    position: sticky;
    top: 0;
    background: #fff;
    border-bottom: 1px solid var(--border);
    z-index: 100;
    box-shadow: 0 2px 4px rgba(0,0,0,0.02);
}

.nav-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    font-size: 20px;
    font-weight: bold;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo::before {
    content: '';
    display: inline-block;
    width: 24px;
    height: 24px;
    background: var(--primary);
    border-radius: 4px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 28px;
}

.nav-menu a {
    font-size: 14px;
    color: var(--text-dark);
    font-weight: 500;
}

.nav-menu a:hover, .nav-menu a.active {
    color: var(--primary);
}

/* Buttons */
.btn-primary {
    background: var(--primary);
    color: #fff;
    padding: 8px 24px;
    border-radius: var(--radius);
    font-weight: 500;
    font-size: 14px;
    display: inline-block;
    text-align: center;
    transition: background 0.2s;
}

.btn-primary:hover {
    background: var(--primary-hover);
}

.btn-outline {
    border: 1px solid var(--border);
    color: var(--text-dark);
    background: #fff;
    padding: 8px 24px;
    border-radius: var(--radius);
    font-weight: 500;
    font-size: 14px;
    display: inline-block;
    text-align: center;
    transition: all 0.2s;
}

.btn-outline:hover {
    border-color: var(--text-gray);
    background: var(--bg-light);
}

.btn-large {
    padding: 12px 36px;
    font-size: 16px;
}

.btn-outline-white {
    border: 1px solid #fff;
    color: #fff;
    padding: 12px 36px;
    border-radius: var(--radius);
    font-weight: 500;
    display: inline-block;
}

/* Hero */
.hero {
    padding: 60px 0;
    background: var(--bg-light);
    border-bottom: 1px solid var(--border);
}

.page-hero {
    padding: 40px 0;
}

.hero-inner {
    display: flex;
    align-items: center;
    gap: 40px;
}

.hero-content {
    flex: 1;
}

.security-badge {
    display: inline-block;
    color: #0F9D58;
    background: rgba(15, 157, 88, 0.1);
    padding: 4px 12px;
    border-radius: 2px;
    font-size: 13px;
    font-weight: bold;
    margin-bottom: 16px;
    border: 1px solid rgba(15, 157, 88, 0.2);
}

.hero-content h1 {
    font-size: 40px;
    line-height: 1.3;
    margin-bottom: 20px;
    color: #202124;
}

.hero-content p {
    font-size: 16px;
    color: var(--text-gray);
    margin-bottom: 32px;
    line-height: 1.6;
}

.hero-btns {
    display: flex;
    gap: 16px;
}

.hero-visual {
    flex: 1;
}

.installer-mockup {
    width: 100%;
    border-radius: 6px;
    box-shadow: 0 12px 24px rgba(0,0,0,0.1), 0 1px 3px rgba(0,0,0,0.08);
    border: 1px solid var(--border);
    background: #fff;
}

/* Data */
.data-section {
    padding: 40px 0;
    border-bottom: 1px solid var(--border);
    background: #fff;
}

.data-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    text-align: center;
}

.data-card h3 {
    font-size: 32px;
    color: var(--primary);
    margin-bottom: 4px;
}

.data-card p {
    color: var(--text-gray);
    font-size: 14px;
}

/* Sections */
.section-header {
    text-align: center;
    margin-bottom: 48px;
}

.section-header h2 {
    font-size: 32px;
    margin-bottom: 12px;
    color: #202124;
}

.section-header p {
    font-size: 16px;
    color: var(--text-gray);
}

/* Features */
.features-section {
    padding: 80px 0;
    background: #fff;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.feature-item {
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: #fff;
    transition: box-shadow 0.2s;
}

.feature-item:hover {
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.f-icon {
    font-size: 32px;
    margin-bottom: 16px;
}

.feature-item h4 {
    font-size: 18px;
    margin-bottom: 8px;
}

.feature-item p {
    color: var(--text-gray);
    font-size: 14px;
}

/* Solutions */
.solutions-section {
    padding: 80px 0;
    background: var(--bg-light);
    border-top: 1px solid var(--border);
}

.solutions-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.solution-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.solution-card img {
    width: 100%;
    height: 180px;
    object-fit: cover;
    border-bottom: 1px solid var(--border);
}

.s-content {
    padding: 20px;
}

.s-content h4 {
    font-size: 18px;
    margin-bottom: 8px;
}

.s-content p {
    color: var(--text-gray);
    font-size: 14px;
}

/* Install Steps */
.install-steps {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.step-card {
    background: #fff;
    border: 1px solid var(--border);
    padding: 32px 24px;
    border-radius: var(--radius);
    text-align: center;
    position: relative;
}

.step-num {
    width: 40px;
    height: 40px;
    background: var(--primary);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: bold;
    margin: 0 auto 16px;
}

.step-card h3 {
    font-size: 18px;
    margin-bottom: 12px;
}

.step-card p {
    color: var(--text-gray);
    font-size: 14px;
}

/* Download Grid */
.download-section {
    padding: 60px 0;
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.download-card {
    border: 1px solid var(--border);
    padding: 32px 24px;
    border-radius: var(--radius);
    text-align: center;
    background: #fff;
}

.d-icon {
    font-size: 40px;
    margin-bottom: 16px;
}

.download-card h3 {
    font-size: 20px;
    margin-bottom: 8px;
}

.download-card p {
    color: var(--text-gray);
    font-size: 14px;
    margin-bottom: 24px;
    min-height: 42px;
}

/* Help Section */
.help-section {
    padding: 60px 0;
}

.faq-container {
    max-width: 760px;
    margin: 0 auto;
}

.faq-container h2 {
    font-size: 28px;
    margin-bottom: 32px;
    text-align: center;
}

.faq-item {
    margin-bottom: 24px;
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: #fff;
}

.faq-item h3 {
    font-size: 18px;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.faq-item p {
    color: var(--text-gray);
    font-size: 15px;
}

.faq-item a {
    color: var(--primary);
}

/* CTA */
.cta-section {
    padding: 80px 0;
    background: var(--primary);
    color: #fff;
    text-align: center;
}

.cta-inner h2 {
    font-size: 36px;
    margin-bottom: 16px;
}

.cta-inner p {
    font-size: 18px;
    opacity: 0.9;
    margin-bottom: 32px;
}

.cta-btns {
    display: flex;
    justify-content: center;
    gap: 16px;
}

.cta-btns .btn-primary {
    background: #fff;
    color: var(--primary);
}

/* Footer */
.footer {
    background: #F8F9FA;
    border-top: 1px solid var(--border);
    padding: 60px 0 24px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 48px;
}

.footer-logo {
    font-size: 20px;
    font-weight: bold;
    color: var(--primary);
    margin-bottom: 12px;
}

.brand-col p {
    color: var(--text-gray);
    font-size: 14px;
}

.footer-col h4 {
    font-size: 16px;
    margin-bottom: 20px;
    color: var(--text-dark);
}

.footer-col a {
    display: block;
    color: var(--text-gray);
    margin-bottom: 12px;
    font-size: 14px;
}

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

.footer-bottom {
    border-top: 1px solid var(--border);
    padding-top: 24px;
    text-align: center;
    color: #80868B;
    font-size: 13px;
}

@media (max-width: 900px) {
    .hero-inner {
        flex-direction: column;
    }
    .nav-menu {
        display: none;
    }
    .features-grid, .solutions-grid, .install-steps, .download-grid, .footer-grid {
        grid-template-columns: 1fr;
    }
    .data-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
    }
    .cta-btns {
        flex-direction: column;
    }
}