/* MChat Official Website - Global Styles */
* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
    --primary: #1a73e8;
    --primary-dark: #1557b0;
    --primary-light: #e8f0fe;
    --accent: #00c853;
    --text: #202124;
    --text-light: #5f6368;
    --bg: #ffffff;
    --bg-alt: #f8f9fa;
    --border: #dadce0;
    --shadow: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
    --radius: 12px;
    --max-width: 1200px;
}
html { scroll-behavior: smooth; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif; color: var(--text); line-height: 1.6; background: var(--bg); }
a { color: var(--primary); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--primary-dark); }
img { max-width: 100%; height: auto; }
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }

/* Navigation */
.navbar { position: sticky; top: 0; z-index: 1000; background: rgba(255,255,255,0.95); backdrop-filter: blur(10px); border-bottom: 1px solid var(--border); padding: 0 24px; }
.navbar .container { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.navbar-logo { display: flex; align-items: center; gap: 10px; font-size: 22px; font-weight: 700; color: var(--primary); }
.navbar-logo:hover { color: var(--primary); }
.navbar-logo svg { width: 32px; height: 32px; }
.navbar-menu { display: flex; align-items: center; gap: 8px; list-style: none; }
.navbar-menu a { display: block; padding: 8px 16px; color: var(--text); font-size: 15px; font-weight: 500; border-radius: 8px; transition: all 0.2s; }
.navbar-menu a:hover, .navbar-menu a.active { color: var(--primary); background: var(--primary-light); }
.navbar-cta { display: inline-block; padding: 10px 24px; background: var(--primary); color: #fff !important; border-radius: 24px; font-weight: 600; font-size: 14px; transition: all 0.2s; }
.navbar-cta:hover { background: var(--primary-dark); color: #fff !important; transform: translateY(-1px); box-shadow: 0 4px 12px rgba(26,115,232,0.3); }
.navbar-toggle { display: none; background: none; border: none; cursor: pointer; padding: 8px; }
.navbar-toggle span { display: block; width: 24px; height: 2px; background: var(--text); margin: 5px 0; transition: 0.3s; }

/* Hero Section */
.hero { position: relative; background: linear-gradient(135deg, #1a73e8 0%, #0d47a1 50%, #1565c0 100%); color: #fff; padding: 120px 24px 100px; text-align: center; overflow: hidden; }
.hero::before { content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%; background: radial-gradient(circle, rgba(255,255,255,0.05) 0%, transparent 60%); }
.hero-content { position: relative; z-index: 1; max-width: 800px; margin: 0 auto; }
.hero h1 { font-size: 52px; font-weight: 800; margin-bottom: 20px; letter-spacing: -1px; line-height: 1.2; }
.hero .subtitle { font-size: 22px; opacity: 0.9; margin-bottom: 16px; font-weight: 300; }
.hero .desc { font-size: 16px; opacity: 0.75; margin-bottom: 40px; max-width: 600px; margin-left: auto; margin-right: auto; }
.hero-buttons { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
.btn { display: inline-block; padding: 14px 36px; border-radius: 28px; font-size: 16px; font-weight: 600; transition: all 0.3s; cursor: pointer; text-align: center; }
.btn-primary { background: #fff; color: var(--primary) !important; }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 25px rgba(0,0,0,0.2); color: var(--primary) !important; }
.btn-outline { background: transparent; color: #fff !important; border: 2px solid rgba(255,255,255,0.5); }
.btn-outline:hover { background: rgba(255,255,255,0.1); border-color: #fff; color: #fff !important; }
.hero-stats { display: flex; justify-content: center; gap: 60px; margin-top: 60px; }
.hero-stat { text-align: center; }
.hero-stat .number { font-size: 36px; font-weight: 800; display: block; }
.hero-stat .label { font-size: 14px; opacity: 0.7; }

/* Section Common */
.section { padding: 80px 24px; }
.section-alt { background: var(--bg-alt); }
.section-header { text-align: center; margin-bottom: 60px; }
.section-header h2 { font-size: 36px; font-weight: 700; margin-bottom: 16px; color: var(--text); }
.section-header p { font-size: 18px; color: var(--text-light); max-width: 600px; margin: 0 auto; }

/* Features Grid */
.features-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; max-width: var(--max-width); margin: 0 auto; }
.feature-card { background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 36px 28px; text-align: center; transition: all 0.3s; }
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--primary); }
.feature-icon { width: 64px; height: 64px; margin: 0 auto 20px; background: var(--primary-light); border-radius: 16px; display: flex; align-items: center; justify-content: center; }
.feature-icon svg { width: 32px; height: 32px; fill: var(--primary); }
.feature-card h3 { font-size: 20px; font-weight: 600; margin-bottom: 12px; }
.feature-card p { font-size: 15px; color: var(--text-light); line-height: 1.7; }

/* Download Section */
.download-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; max-width: var(--max-width); margin: 0 auto; }
.download-card { background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 32px 24px; text-align: center; transition: all 0.3s; }
.download-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--primary); }
.download-card svg { width: 48px; height: 48px; margin-bottom: 16px; }
.download-card h3 { font-size: 18px; font-weight: 600; margin-bottom: 8px; }
.download-card .version { font-size: 13px; color: var(--text-light); margin-bottom: 16px; }
.download-card .btn-download { display: inline-block; padding: 10px 28px; background: var(--primary); color: #fff !important; border-radius: 24px; font-weight: 600; font-size: 14px; transition: all 0.2s; }
.download-card .btn-download:hover { background: var(--primary-dark); color: #fff !important; }
.qr-section { text-align: center; margin-top: 48px; padding: 32px; background: var(--bg-alt); border-radius: var(--radius); }
.qr-section p { color: var(--text-light); margin-bottom: 16px; }

/* Security Section */
.security-content { max-width: var(--max-width); margin: 0 auto; display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.security-text h3 { font-size: 28px; font-weight: 700; margin-bottom: 20px; }
.security-text p { font-size: 16px; color: var(--text-light); margin-bottom: 16px; line-height: 1.8; }
.security-list { list-style: none; }
.security-list li { display: flex; align-items: flex-start; gap: 12px; margin-bottom: 16px; font-size: 15px; }
.security-list li svg { width: 24px; height: 24px; fill: var(--accent); flex-shrink: 0; margin-top: 2px; }
.security-visual { background: linear-gradient(135deg, var(--primary-light), #e3f2fd); border-radius: var(--radius); padding: 48px; text-align: center; }
.security-visual svg { width: 200px; height: 200px; fill: var(--primary); opacity: 0.8; }

/* News Section */
.news-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; max-width: var(--max-width); margin: 0 auto; }
.news-card { background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; transition: all 0.3s; }
.news-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.news-card-img { height: 180px; background: linear-gradient(135deg, var(--primary-light), #e3f2fd); display: flex; align-items: center; justify-content: center; }
.news-card-img svg { width: 64px; height: 64px; fill: var(--primary); opacity: 0.5; }
.news-card-body { padding: 24px; }
.news-card-date { font-size: 13px; color: var(--text-light); margin-bottom: 8px; }
.news-card-body h3 { font-size: 18px; font-weight: 600; margin-bottom: 10px; }
.news-card-body p { font-size: 14px; color: var(--text-light); line-height: 1.7; }

/* Footer */
.footer { background: #1a1a2e; color: rgba(255,255,255,0.7); padding: 60px 24px 30px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; max-width: var(--max-width); margin: 0 auto 40px; }
.footer-brand h3 { color: #fff; font-size: 22px; margin-bottom: 12px; }
.footer-brand p { font-size: 14px; line-height: 1.8; }
.footer-col h4 { color: #fff; font-size: 16px; margin-bottom: 16px; }
.footer-col ul { list-style: none; }
.footer-col ul li { margin-bottom: 10px; }
.footer-col ul li a { color: rgba(255,255,255,0.6); font-size: 14px; transition: color 0.2s; }
.footer-col ul li a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.1); padding-top: 24px; text-align: center; max-width: var(--max-width); margin: 0 auto; }
.footer-bottom p { font-size: 13px; color: rgba(255,255,255,0.4); }
.footer-social { display: flex; gap: 16px; margin-top: 16px; }
.footer-social a { display: inline-flex; align-items: center; justify-content: center; width: 36px; height: 36px; border-radius: 50%; background: rgba(255,255,255,0.1); color: rgba(255,255,255,0.6); transition: all 0.2s; }
.footer-social a:hover { background: var(--primary); color: #fff; }
.footer-social a svg { width: 18px; height: 18px; fill: currentColor; }

/* Page Header (for inner pages) */
.page-header { background: linear-gradient(135deg, #1a73e8 0%, #0d47a1 100%); color: #fff; padding: 80px 24px 60px; text-align: center; }
.page-header h1 { font-size: 40px; font-weight: 700; margin-bottom: 12px; }
.page-header p { font-size: 18px; opacity: 0.8; max-width: 600px; margin: 0 auto; }

/* Help / FAQ */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item { background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 20px; overflow: hidden; }
.faq-item h3 { padding: 24px 28px; font-size: 18px; font-weight: 600; background: var(--bg-alt); border-bottom: 1px solid var(--border); display: flex; align-items: center; gap: 12px; }
.faq-item h3 .faq-num { display: inline-flex; align-items: center; justify-content: center; width: 32px; height: 32px; background: var(--primary); color: #fff; border-radius: 50%; font-size: 14px; font-weight: 700; flex-shrink: 0; }
.faq-answer { padding: 24px 28px; }
.faq-answer p { font-size: 15px; color: var(--text-light); margin-bottom: 16px; line-height: 1.8; }
.faq-steps { list-style: none; counter-reset: step; }
.faq-steps li { counter-increment: step; display: flex; align-items: flex-start; gap: 14px; margin-bottom: 14px; font-size: 15px; line-height: 1.7; }
.faq-steps li::before { content: counter(step); display: inline-flex; align-items: center; justify-content: center; min-width: 28px; height: 28px; background: var(--primary-light); color: var(--primary); border-radius: 50%; font-size: 13px; font-weight: 700; flex-shrink: 0; margin-top: 2px; }

/* About Page */
.about-intro { max-width: 800px; margin: 0 auto; text-align: center; }
.about-intro p { font-size: 17px; color: var(--text-light); line-height: 1.9; margin-bottom: 20px; }
.values-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; max-width: var(--max-width); margin: 0 auto; }
.value-card { text-align: center; padding: 36px 24px; }
.value-card svg { width: 56px; height: 56px; fill: var(--primary); margin-bottom: 20px; }
.value-card h3 { font-size: 20px; font-weight: 600; margin-bottom: 12px; }
.value-card p { font-size: 15px; color: var(--text-light); line-height: 1.7; }
.timeline { max-width: 700px; margin: 0 auto; position: relative; padding-left: 40px; }
.timeline::before { content: ''; position: absolute; left: 15px; top: 0; bottom: 0; width: 2px; background: var(--border); }
.timeline-item { position: relative; margin-bottom: 36px; }
.timeline-item::before { content: ''; position: absolute; left: -33px; top: 6px; width: 12px; height: 12px; background: var(--primary); border-radius: 50%; border: 3px solid var(--primary-light); }
.timeline-item h4 { font-size: 17px; font-weight: 600; margin-bottom: 6px; }
.timeline-item p { font-size: 14px; color: var(--text-light); line-height: 1.7; }

/* Security Page Detail */
.security-features { display: grid; grid-template-columns: repeat(2, 1fr); gap: 32px; max-width: var(--max-width); margin: 0 auto; }
.security-feature-card { background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 36px; transition: all 0.3s; }
.security-feature-card:hover { box-shadow: var(--shadow-lg); border-color: var(--primary); }
.security-feature-card svg { width: 48px; height: 48px; fill: var(--primary); margin-bottom: 20px; }
.security-feature-card h3 { font-size: 20px; font-weight: 600; margin-bottom: 12px; }
.security-feature-card p { font-size: 15px; color: var(--text-light); line-height: 1.8; }

/* Features Page Detail */
.feature-detail { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; max-width: var(--max-width); margin: 0 auto; padding: 40px 0; }
.feature-detail:nth-child(even) { direction: rtl; }
.feature-detail:nth-child(even) > * { direction: ltr; }
.feature-detail-text h3 { font-size: 28px; font-weight: 700; margin-bottom: 16px; }
.feature-detail-text p { font-size: 16px; color: var(--text-light); line-height: 1.8; margin-bottom: 16px; }
.feature-detail-text ul { list-style: none; }
.feature-detail-text ul li { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; font-size: 15px; }
.feature-detail-text ul li svg { width: 20px; height: 20px; fill: var(--accent); flex-shrink: 0; }
.feature-detail-visual { background: linear-gradient(135deg, var(--primary-light), #e3f2fd); border-radius: var(--radius); padding: 48px; text-align: center; min-height: 300px; display: flex; align-items: center; justify-content: center; }
.feature-detail-visual svg { width: 160px; height: 160px; fill: var(--primary); opacity: 0.6; }

/* Responsive */
@media (max-width: 1024px) {
    .features-grid, .news-grid, .values-grid { grid-template-columns: repeat(2, 1fr); }
    .download-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: repeat(2, 1fr); }
    .security-content { grid-template-columns: 1fr; }
    .feature-detail { grid-template-columns: 1fr; gap: 32px; }
    .feature-detail:nth-child(even) { direction: ltr; }
    .security-features { grid-template-columns: 1fr; }
}
@media (max-width: 768px) {
    .navbar-menu { display: none; position: absolute; top: 64px; left: 0; right: 0; background: #fff; flex-direction: column; padding: 16px; border-bottom: 1px solid var(--border); box-shadow: var(--shadow); }
    .navbar-menu.active { display: flex; }
    .navbar-toggle { display: block; }
    .hero h1 { font-size: 32px; }
    .hero .subtitle { font-size: 18px; }
    .hero-stats { flex-direction: column; gap: 24px; }
    .features-grid, .news-grid, .values-grid { grid-template-columns: 1fr; }
    .download-grid { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
    .section { padding: 60px 16px; }
    .section-header h2 { font-size: 28px; }
    .page-header h1 { font-size: 30px; }
    .hero { padding: 80px 16px 60px; }
}