/* LinkChat Official Site - style.css */
:root {
    --primary: #2563EB;
    --primary-dark: #1d4ed8;
    --primary-light: #dbeafe;
    --text: #1e293b;
    --text-light: #64748b;
    --bg: #ffffff;
    --bg-gray: #f8fafc;
    --border: #e2e8f0;
    --radius: 8px;
    --shadow: 0 2px 12px rgba(0,0,0,0.08);
    --max-width: 1200px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    color: var(--text);
    line-height: 1.7;
    background: var(--bg);
}

a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }

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

/* Header */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    height: 64px;
}

.header-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo svg {
    width: 32px;
    height: 32px;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: var(--text);
    font-size: 0.95rem;
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
    transition: all 0.2s;
}

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

.nav-download-btn {
    background: var(--primary);
    color: #fff !important;
    padding: 0.5rem 1.2rem !important;
    border-radius: var(--radius);
    border-bottom: none !important;
}

.nav-download-btn:hover {
    background: var(--primary-dark);
    color: #fff !important;
    border-bottom-color: transparent !important;
}

/* Mobile menu */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text);
}

/* Hero */
.hero {
    padding: 8rem 2rem 4rem;
    text-align: center;
    background: linear-gradient(135deg, #f0f7ff 0%, #e8f0fe 100%);
}

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 1rem;
    color: var(--text);
}

.hero .subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto 2rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn-primary {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--primary);
    color: #fff;
    padding: 0.85rem 2rem;
    border-radius: var(--radius);
    font-size: 1.05rem;
    font-weight: 500;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
}

.btn-primary:hover {
    background: var(--primary-dark);
    color: #fff;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37,99,235,0.3);
}

.btn-outline {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: #fff;
    color: var(--primary);
    padding: 0.85rem 2rem;
    border-radius: var(--radius);
    font-size: 1.05rem;
    font-weight: 500;
    border: 1px solid var(--primary);
    transition: all 0.2s;
    cursor: pointer;
}

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

/* Sections */
.section {
    padding: 4rem 2rem;
    max-width: var(--max-width);
    margin: 0 auto;
}

.section-gray {
    background: var(--bg-gray);
}

.section-gray .section {
    padding: 4rem 2rem;
}

.section-title {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 0.5rem;
}

.section-desc {
    text-align: center;
    color: var(--text-light);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* Feature grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-top: 2rem;
}

.feature-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem;
    transition: all 0.2s;
}

.feature-card:hover {
    box-shadow: var(--shadow);
    transform: translateY(-2px);
}

.feature-card .icon {
    width: 48px;
    height: 48px;
    background: var(--primary-light);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.feature-card h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}

.feature-card p {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* Article content */
.article-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem 0;
}

.article-content h2 {
    font-size: 1.5rem;
    margin: 2rem 0 1rem;
    color: var(--text);
}

.article-content h3 {
    font-size: 1.2rem;
    margin: 1.5rem 0 0.8rem;
    color: var(--text);
}

.article-content p {
    margin-bottom: 1rem;
    color: #374151;
    font-size: 1rem;
}

.article-content ul, .article-content ol {
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

.article-content li {
    margin-bottom: 0.5rem;
    color: #374151;
}

/* Testimonials */
.testimonials {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.testimonial-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
}

.testimonial-card .stars {
    color: #f59e0b;
    margin-bottom: 0.5rem;
}

.testimonial-card .text {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 1rem;
    font-style: italic;
}

.testimonial-card .author {
    font-size: 0.85rem;
    font-weight: 600;
}

/* Download page */
.download-hero {
    text-align: center;
    padding: 6rem 2rem 3rem;
    background: linear-gradient(135deg, #f0f7ff 0%, #e8f0fe 100%);
}

.download-box {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2.5rem;
    max-width: 500px;
    margin: 2rem auto;
    box-shadow: var(--shadow);
    text-align: center;
}

.download-box .version-tag {
    display: inline-block;
    background: var(--primary-light);
    color: var(--primary);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.85rem;
    margin-bottom: 1rem;
}

.download-box .file-info {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-top: 1rem;
}

/* Version history */
.version-list {
    max-width: 700px;
    margin: 2rem auto;
}

.version-item {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.version-item .info h4 {
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.version-item .info p {
    color: var(--text-light);
    font-size: 0.85rem;
}

.version-item .btn-sm {
    background: var(--primary);
    color: #fff;
    padding: 0.4rem 1rem;
    border-radius: var(--radius);
    font-size: 0.85rem;
    white-space: nowrap;
}

.version-item .btn-sm:hover {
    background: var(--primary-dark);
}

/* Docs page */
.docs-content {
    max-width: 800px;
    margin: 0 auto;
}

.docs-content .step {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.docs-content .step-number {
    width: 40px;
    height: 40px;
    background: var(--primary);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
}

.docs-content .step-content h3 {
    margin-bottom: 0.5rem;
}

.docs-content .step-content p {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* FAQ */
.faq-list {
    max-width: 700px;
    margin: 0 auto;
}

.faq-item {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 0.75rem;
    overflow: hidden;
}

.faq-item summary {
    padding: 1rem 1.5rem;
    font-weight: 500;
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-item summary::after {
    content: "+";
    font-size: 1.2rem;
    color: var(--primary);
}

.faq-item[open] summary::after {
    content: "-";
}

.faq-item .answer {
    padding: 0 1.5rem 1rem;
    color: var(--text-light);
}

/* About page */
.about-section {
    max-width: 800px;
    margin: 0 auto;
}

.team-values {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    margin-top: 2rem;
}

.value-card {
    padding: 1.5rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

.value-card h3 {
    margin-bottom: 0.5rem;
    color: var(--primary);
}

/* Footer */
.site-footer {
    background: #1e293b;
    color: #94a3b8;
    padding: 3rem 2rem 1.5rem;
}

.footer-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 2rem;
}

.footer-brand p {
    margin-top: 0.5rem;
    font-size: 0.9rem;
}

.footer-col h4 {
    color: #fff;
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.footer-col a {
    display: block;
    color: #94a3b8;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.footer-col a:hover {
    color: #fff;
}

.footer-bottom {
    max-width: var(--max-width);
    margin: 2rem auto 0;
    padding-top: 1.5rem;
    border-top: 1px solid #334155;
    text-align: center;
    font-size: 0.85rem;
}

/* Responsive */
@media (max-width: 768px) {
    .menu-toggle { display: block; }
    .nav-links {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: #fff;
        flex-direction: column;
        padding: 1rem 2rem;
        border-bottom: 1px solid var(--border);
        gap: 0.5rem;
    }
    .nav-links.open { display: flex; }
    .hero h1 { font-size: 2rem; }
    .feature-grid { grid-template-columns: 1fr; }
    .testimonials { grid-template-columns: 1fr; }
    .footer-inner { grid-template-columns: 1fr 1fr; }
    .team-values { grid-template-columns: 1fr; }
    .version-item { flex-direction: column; gap: 1rem; align-items: flex-start; }
    .docs-content .step { flex-direction: column; }
}

/* Page transitions */
.page { display: none; }
.page.active { display: block; }

/* Utility */
.text-center { text-align: center; }
.mt-2 { margin-top: 2rem; }
.mb-2 { margin-bottom: 2rem; }