/* ========================================
   RankFlow SEO Service Website
   Style: Light, Warm, Professional
   ======================================== */

/* ---------- CSS Variables ---------- */
:root {
    --bg: #FAF8F5;
    --bg-alt: #F4F1EC;
    --bg-card: #FFFFFF;
    --fg: #1F1E1C;
    --fg-muted: #5C5951;
    --fg-light: #8A867C;
    --accent: #B87333;
    --accent-hover: #9A5F28;
    --accent-soft: rgba(184, 115, 51, 0.1);
    --jade: #3A8F72;
    --jade-soft: rgba(58, 143, 114, 0.1);
    --border: #E5E0D6;
    --border-dark: #D0C9BC;

    --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;

    --shadow: 0 1px 3px rgba(31, 30, 28, 0.04);
    --shadow-md: 0 4px 12px rgba(31, 30, 28, 0.05);
    --shadow-lg: 0 8px 24px rgba(31, 30, 28, 0.06);

    --radius: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;

    --transition: 180ms ease;
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.65;
    color: var(--fg);
    background-color: var(--bg);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

input, textarea, select {
    font-family: inherit;
    font-size: 1rem;
}

ul, ol {
    list-style: none;
}

/* ---------- Typography ---------- */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.35;
    color: var(--fg);
    letter-spacing: -0.01em;
}

h1 {
    font-size: clamp(2rem, 5vw, 2.75rem);
    font-weight: 700;
    letter-spacing: -0.02em;
}

h2 {
    font-size: clamp(1.5rem, 4vw, 2rem);
}

h3 {
    font-size: 1.125rem;
    font-weight: 600;
}

p {
    color: var(--fg-muted);
}

.text-accent {
    color: var(--accent);
}

/* ---------- Layout ---------- */
.container {
    width: 100%;
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 20px;
}

@media (min-width: 768px) {
    .container { padding: 0 32px; }
}

.section {
    padding: 72px 0;
}

@media (min-width: 768px) {
    .section { padding: 96px 0; }
}

.section-header {
    text-align: center;
    max-width: 560px;
    margin: 0 auto 48px;
}

.section-title {
    margin-bottom: 12px;
}

.section-desc {
    font-size: 1rem;
    line-height: 1.7;
}

/* ---------- Navigation ---------- */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(250, 248, 245, 0.9);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
}

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

.nav-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
    font-size: 1.0625rem;
    color: var(--fg);
}

.nav-logo-icon {
    width: 28px;
    height: 28px;
    background: var(--accent);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.nav-logo-icon svg {
    width: 16px;
    height: 16px;
    color: white;
}

.nav-menu {
    display: none;
    align-items: center;
    gap: 32px;
}

@media (min-width: 1024px) {
    .nav-menu { display: flex; }
}

.nav-link {
    font-size: 0.9375rem;
    color: var(--fg-muted);
}

.nav-link:hover {
    color: var(--fg);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    color: var(--fg);
}

@media (min-width: 1024px) {
    .nav-toggle { display: none; }
}

/* Mobile Menu */
.mobile-menu {
    display: none;
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg);
    padding: 20px;
    z-index: 999;
}

.mobile-menu.active {
    display: block;
}

.mobile-menu-link {
    display: block;
    padding: 14px 0;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--fg);
    border-bottom: 1px solid var(--border);
}

/* ---------- Buttons ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-weight: 500;
    font-size: 0.875rem;
    padding: 10px 20px;
    border-radius: var(--radius);
    transition: all var(--transition);
    white-space: nowrap;
}

.btn-primary {
    background: var(--accent);
    color: white;
}

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

.btn-secondary {
    background: var(--fg);
    color: white;
}

.btn-secondary:hover {
    background: #3A3937;
}

.btn-outline {
    background: transparent;
    color: var(--fg);
    border: 1px solid var(--border-dark);
}

.btn-outline:hover {
    background: var(--bg-alt);
    border-color: var(--fg-muted);
}

.btn-lg {
    padding: 14px 28px;
    font-size: 0.9375rem;
}

.btn-sm {
    padding: 8px 16px;
    font-size: 0.8125rem;
}

/* ---------- Hero Section ---------- */
.hero {
    padding-top: 108px;
    padding-bottom: 72px;
    background: var(--bg);
}

.hero-inner {
    display: grid;
    gap: 48px;
    align-items: center;
}

@media (min-width: 1024px) {
    .hero-inner {
        grid-template-columns: 1fr 1fr;
        gap: 64px;
    }
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    margin-bottom: 20px;
}

.hero-desc {
    font-size: 1.0625rem;
    margin-bottom: 32px;
    max-width: 480px;
    line-height: 1.75;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    margin-bottom: 48px;
}

.hero-stats {
    display: flex;
    gap: 40px;
    padding-top: 28px;
    border-top: 1px solid var(--border);
}

.hero-stat-value {
    font-size: 1.625rem;
    font-weight: 700;
    color: var(--fg);
}

.hero-stat-label {
    font-size: 0.875rem;
    color: var(--fg-light);
    margin-top: 4px;
}

/* Hero Visual */
.hero-visual {
    position: relative;
}

.hero-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: 24px;
    box-shadow: var(--shadow-md);
}

.hero-card-header {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 20px;
}

.hero-card-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--border);
}

.hero-card-dot:nth-child(3) {
    background: var(--jade);
}

.hero-card-title {
    margin-left: auto;
    font-size: 0.8125rem;
    color: var(--fg-light);
}

.hero-card-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-bottom: 14px;
}

.hero-card-stat {
    background: var(--bg-alt);
    border-radius: var(--radius);
    padding: 18px;
}

.hero-card-stat-label {
    font-size: 0.8125rem;
    color: var(--fg-light);
    margin-bottom: 6px;
}

.hero-card-stat-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--fg);
}

.hero-card-stat-change {
    font-size: 0.8125rem;
    color: var(--jade);
    margin-top: 6px;
}

.hero-card-chart {
    background: var(--bg-alt);
    border-radius: var(--radius);
    padding: 18px;
}

.hero-card-chart-label {
    font-size: 0.8125rem;
    color: var(--fg-light);
    margin-bottom: 14px;
}

.hero-card-bars {
    display: flex;
    align-items: flex-end;
    gap: 6px;
    height: 60px;
}

.hero-card-bar {
    flex: 1;
    background: var(--accent);
    border-radius: 4px 4px 0 0;
}

/* ---------- About Section ---------- */
.about {
    background: var(--bg-card);
}

.about-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 768px) {
    .about-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 24px;
    }
}

.about-card {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 28px;
}

.about-card-icon {
    width: 44px;
    height: 44px;
    background: var(--accent-soft);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 18px;
}

.about-card-icon svg {
    width: 22px;
    height: 22px;
    color: var(--accent);
}

.about-card-title {
    font-size: 1.0625rem;
    margin-bottom: 8px;
}

.about-card-desc {
    font-size: 0.9375rem;
    line-height: 1.65;
}

/* ---------- Services Section ---------- */
.services {
    background: var(--bg);
}

.services-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 768px) {
    .services-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }
}

@media (min-width: 1024px) {
    .services-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.service-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 26px;
}

.service-card-icon {
    width: 42px;
    height: 42px;
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 18px;
}

.service-card-icon svg {
    width: 20px;
    height: 20px;
    color: white;
}

.service-card-icon.ecommerce { background: var(--fg); }
.service-card-icon.local { background: var(--jade); }
.service-card-icon.technical { background: #6B5B95; }
.service-card-icon.content { background: var(--accent); }

.service-card-title {
    font-size: 1rem;
    margin-bottom: 8px;
}

.service-card-desc {
    font-size: 0.875rem;
    margin-bottom: 14px;
    line-height: 1.6;
}

.service-card-link {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--fg-muted);
}

/* ---------- Process Section ---------- */
.process {
    background: var(--bg-card);
}

.process-grid {
    display: grid;
    gap: 32px;
}

@media (min-width: 768px) {
    .process-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 36px;
    }
}

.process-step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: var(--accent-soft);
    color: var(--accent);
    font-weight: 600;
    font-size: 1rem;
    border-radius: 50%;
    margin-bottom: 18px;
}

.process-step-title {
    font-size: 1.125rem;
    margin-bottom: 10px;
}

.process-step-desc {
    font-size: 0.9375rem;
    margin-bottom: 18px;
    line-height: 1.65;
}

.process-step-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.process-tag {
    background: var(--bg);
    border: 1px solid var(--border);
    font-size: 0.8125rem;
    padding: 5px 12px;
    border-radius: 100px;
    color: var(--fg-muted);
}

/* ---------- Pricing Section ---------- */
.pricing {
    background: var(--bg);
}

.pricing-grid {
    display: grid;
    gap: 20px;
    max-width: 920px;
    margin: 0 auto;
}

@media (min-width: 768px) {
    .pricing-grid {
        grid-template-columns: repeat(3, 1fr);
        align-items: stretch;
    }
}

.pricing-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 28px;
    display: flex;
    flex-direction: column;
}

.pricing-card.featured {
    border-color: var(--accent);
    position: relative;
}

.pricing-card.featured::before {
    content: '推荐';
    position: absolute;
    top: -10px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--accent);
    color: white;
    font-size: 0.75rem;
    font-weight: 500;
    padding: 4px 14px;
    border-radius: 100px;
}

.pricing-header {
    text-align: center;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.pricing-name {
    font-size: 1.0625rem;
    margin-bottom: 4px;
}

.pricing-desc {
    font-size: 0.875rem;
    color: var(--fg-muted);
}

.pricing-price {
    margin-top: 14px;
}

.pricing-amount {
    font-size: 1.5rem;
    font-weight: 700;
}

.pricing-period {
    font-size: 0.875rem;
    color: var(--fg-muted);
}

.pricing-delivery {
    font-size: 0.8125rem;
    color: var(--fg-light);
    margin-top: 6px;
}

.pricing-features {
    flex: 1;
    margin-bottom: 20px;
}

.pricing-feature {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 7px 0;
}

.pricing-feature svg {
    width: 16px;
    height: 16px;
    color: var(--jade);
    flex-shrink: 0;
    margin-top: 2px;
}

.pricing-feature span {
    font-size: 0.875rem;
    color: var(--fg-muted);
}

.pricing-card .btn {
    width: 100%;
}

/* ---------- Trends Section ---------- */
.trends {
    background: var(--bg-card);
}

.trends-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 768px) {
    .trends-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

.trend-card {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 28px;
}

.trend-card-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 18px;
}

.trend-card-icon svg {
    width: 22px;
    height: 22px;
    color: white;
}

.trend-card-icon.eeat { background: var(--jade); }
.trend-card-icon.omnichannel { background: #6B5B95; }
.trend-card-icon.aeo { background: var(--accent); }

.trend-card-title {
    font-size: 1.125rem;
    margin-bottom: 10px;
}

.trend-card-desc {
    font-size: 0.9375rem;
    line-height: 1.65;
}

/* ---------- Contact Section ---------- */
.contact {
    background: var(--bg);
}

.contact-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 768px) {
    .contact-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
    }
}

@media (min-width: 1024px) {
    .contact-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.contact-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 28px;
    text-align: center;
}

.contact-card-icon {
    width: 48px;
    height: 48px;
    background: var(--accent-soft);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 16px;
}

.contact-card-icon svg {
    width: 22px;
    height: 22px;
    color: var(--accent);
}

.contact-card-title {
    font-size: 0.9375rem;
    margin-bottom: 6px;
}

.contact-card-value {
    font-size: 1.0625rem;
    font-weight: 600;
    color: var(--fg);
}

.contact-card-value a {
    color: var(--fg);
}

.contact-card-value a:hover {
    color: var(--accent);
}

/* ---------- Footer ---------- */
.footer {
    background: var(--bg-alt);
    border-top: 1px solid var(--border);
    padding: 48px 0 32px;
}

.footer-grid {
    display: grid;
    gap: 32px;
    margin-bottom: 40px;
}

@media (min-width: 768px) {
    .footer-grid {
        grid-template-columns: 2fr 1fr 1fr 1fr;
        gap: 40px;
    }
}

.footer-brand {
    max-width: 280px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
    font-size: 1.0625rem;
    margin-bottom: 12px;
    color: var(--fg);
}

.footer-desc {
    font-size: 0.875rem;
    color: var(--fg-light);
    line-height: 1.65;
    margin-bottom: 18px;
}

.footer-social {
    display: flex;
    gap: 10px;
}

.footer-social-link {
    width: 34px;
    height: 34px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.footer-social-link svg {
    width: 16px;
    height: 16px;
    fill: var(--fg-muted);
}

.footer-title {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--fg);
    margin-bottom: 16px;
}

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

.footer-link {
    font-size: 0.875rem;
    color: var(--fg-light);
}

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

.footer-bottom {
    padding-top: 24px;
    border-top: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    gap: 12px;
    align-items: center;
}

@media (min-width: 768px) {
    .footer-bottom {
        flex-direction: row;
        justify-content: space-between;
    }
}

.footer-copyright {
    font-size: 0.8125rem;
    color: var(--fg-light);
}

.footer-legal {
    display: flex;
    gap: 20px;
}

.footer-legal-link {
    font-size: 0.8125rem;
    color: var(--fg-light);
}

/* ---------- Utility Classes ---------- */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.hidden {
    display: none !important;
}