/* ===== Quickq q19 — Tangerine Light Theme ===== */
:root {
  --primary: #FF6B2C;
  --primary-hover: #E85A1B;
  --primary-light: #FFF4EF;
  --primary-soft: #FFDCC8;
  --dark: #111827;
  --dark-2: #1F2937;
  --surface: #F7F8FA;
  --surface-2: #EEF0F4;
  --white: #FFFFFF;
  --text-primary: #111827;
  --text-secondary: #4B5563;
  --text-muted: #9CA3AF;
  --border: #E5E7EB;
  --border-light: #F3F4F6;
  --success: #10B981;
  --radius-xs: 6px;
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,.06);
  --shadow-lg: 0 12px 40px rgba(0,0,0,.08);
  --font: -apple-system, 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  --transition: .25s cubic-bezier(.4,0,.2,1);
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }
body { font-family: var(--font); color: var(--text-primary); background: var(--white); line-height: 1.7; font-size: 15px; }
a { color: var(--primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--primary-hover); }
img { max-width: 100%; display: block; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 24px; }

/* ===== Header ===== */
.header { position: fixed; top: 0; left: 0; right: 0; z-index: 100; background: rgba(255,255,255,.82); backdrop-filter: blur(18px); -webkit-backdrop-filter: blur(18px); border-bottom: 1px solid var(--border-light); transition: box-shadow var(--transition); }
.header.scrolled { box-shadow: 0 1px 12px rgba(0,0,0,.06); }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; max-width: 1100px; margin: 0 auto; padding: 0 24px; }
.header-brand { display: flex; align-items: center; gap: 8px; font-size: 1.2rem; font-weight: 800; color: var(--dark); text-decoration: none; }
.brand-dot { display: inline-block; width: 28px; height: 28px; border-radius: 8px; background: var(--primary); color: #fff; font-size: .82rem; font-weight: 800; text-align: center; line-height: 28px; }
.header-nav { display: flex; align-items: center; gap: 4px; }
.header-nav a { padding: 7px 14px; border-radius: var(--radius-xs); font-size: .88rem; font-weight: 500; color: var(--text-secondary); transition: all var(--transition); }
.header-nav a:hover { color: var(--primary); background: var(--primary-light); }
.nav-cta { background: var(--primary) !important; color: #fff !important; font-weight: 600 !important; }
.nav-cta:hover { background: var(--primary-hover) !important; color: #fff !important; }
.menu-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; padding: 4px; }
.menu-toggle span { display: block; width: 22px; height: 2px; background: var(--dark); border-radius: 2px; transition: var(--transition); }
.mobile-nav { display: none; position: fixed; top: 64px; left: 0; right: 0; background: var(--white); border-bottom: 1px solid var(--border); z-index: 99; padding: 12px 24px; }
.mobile-nav.open { display: flex; flex-direction: column; gap: 4px; }
.mobile-nav a { display: block; padding: 10px 16px; font-size: .92rem; color: var(--text-secondary); border-radius: var(--radius-xs); }
.mobile-nav a:hover { background: var(--primary-light); color: var(--primary); }

/* ===== Hero ===== */
.hero { padding: 140px 0 80px; text-align: center; position: relative; overflow: hidden; }
.hero::before { content: ''; position: absolute; top: -200px; right: -200px; width: 600px; height: 600px; background: radial-gradient(circle, rgba(255,107,44,.08) 0%, transparent 70%); pointer-events: none; }
.hero::after { content: ''; position: absolute; bottom: -100px; left: -150px; width: 400px; height: 400px; background: radial-gradient(circle, rgba(255,107,44,.05) 0%, transparent 70%); pointer-events: none; }
.hero-badge { display: inline-flex; align-items: center; gap: 6px; padding: 6px 16px; border-radius: 100px; background: var(--primary-light); color: var(--primary); font-size: .78rem; font-weight: 600; margin-bottom: 24px; }
.hero h1 { font-size: clamp(2.2rem, 5.5vw, 3.6rem); font-weight: 800; line-height: 1.2; letter-spacing: -.02em; margin-bottom: 20px; position: relative; }
.hero h1 .hl { color: var(--primary); }
.hero p { font-size: 1.08rem; color: var(--text-secondary); max-width: 520px; margin: 0 auto 32px; line-height: 1.7; }
.hero-buttons { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* ===== Page Hero (sub pages) ===== */
.page-hero { padding: 120px 0 48px; text-align: center; }
.page-hero h1 { font-size: clamp(1.6rem, 4vw, 2.4rem); font-weight: 800; letter-spacing: -.015em; margin-bottom: 12px; }
.page-hero h1 .hl { color: var(--primary); }
.page-hero p { color: var(--text-secondary); font-size: 1rem; max-width: 500px; margin: 0 auto; }
.page-hero .hero-badge { margin-bottom: 16px; }

/* ===== Buttons ===== */
.btn { display: inline-flex; align-items: center; gap: 6px; padding: 10px 22px; border-radius: var(--radius-sm); font-size: .9rem; font-weight: 600; border: none; cursor: pointer; transition: all var(--transition); text-decoration: none; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-1px); box-shadow: 0 4px 12px rgba(255,107,44,.3); color: #fff; }
.btn-dark { background: var(--dark); color: #fff; }
.btn-dark:hover { background: var(--dark-2); color: #fff; }
.btn-outline { background: transparent; border: 1.5px solid var(--border); color: var(--text-primary); }
.btn-outline:hover { border-color: var(--primary); color: var(--primary); }
.btn-lg { padding: 14px 32px; font-size: .95rem; border-radius: var(--radius-md); }

/* ===== Section ===== */
.section { padding: 64px 0; }
.section-title { font-size: 1.5rem; font-weight: 800; letter-spacing: -.015em; margin-bottom: 8px; }
.section-desc { color: var(--text-secondary); font-size: .95rem; margin-bottom: 36px; max-width: 500px; }
.section-title.center, .section-desc.center { margin-left: auto; margin-right: auto; text-align: center; }

/* ===== Card ===== */
.card { background: var(--white); border: 1px solid var(--border); border-radius: var(--radius-md); padding: 28px; transition: all var(--transition); }
.card:hover { box-shadow: var(--shadow-md); border-color: transparent; transform: translateY(-2px); }

/* ===== Feature Grid ===== */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.feature-card { padding: 28px; border-radius: var(--radius-md); border: 1px solid var(--border); transition: all var(--transition); background: var(--white); }
.feature-card:hover { box-shadow: var(--shadow-md); border-color: transparent; transform: translateY(-2px); }
.feature-icon { width: 44px; height: 44px; border-radius: var(--radius-sm); background: var(--primary-light); display: flex; align-items: center; justify-content: center; font-size: 1.2rem; margin-bottom: 16px; }
.feature-card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 8px; }
.feature-card p { font-size: .85rem; color: var(--text-secondary); line-height: 1.65; }

/* ===== Stats ===== */
.stats-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin: 40px 0; }
.stat-card { text-align: center; padding: 28px 16px; border-radius: var(--radius-md); background: var(--surface); }
.stat-num { font-size: 2rem; font-weight: 800; color: var(--primary); letter-spacing: -.02em; }
.stat-label { font-size: .82rem; color: var(--text-muted); margin-top: 4px; }

/* ===== Steps ===== */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.step-card { text-align: center; padding: 28px 20px; border-radius: var(--radius-md); border: 1px solid var(--border); background: var(--white); position: relative; }
.step-num { width: 36px; height: 36px; border-radius: 50%; background: var(--primary); color: #fff; font-weight: 700; font-size: .9rem; display: inline-flex; align-items: center; justify-content: center; margin-bottom: 14px; }
.step-card h3 { font-size: .95rem; font-weight: 700; margin-bottom: 6px; }
.step-card p { font-size: .82rem; color: var(--text-secondary); line-height: 1.6; }

/* ===== Platforms ===== */
.platform-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.platform-card { text-align: center; padding: 28px 16px; border-radius: var(--radius-md); border: 1px solid var(--border); background: var(--white); transition: all var(--transition); text-decoration: none; color: inherit; }
.platform-card:hover { border-color: var(--primary); box-shadow: var(--shadow-md); transform: translateY(-2px); }
.platform-icon { font-size: 2rem; margin-bottom: 10px; }
.platform-card h3 { font-size: .92rem; font-weight: 700; margin-bottom: 4px; }
.platform-card p { font-size: .78rem; color: var(--text-muted); }

/* ===== CTA Box ===== */
.cta-box { text-align: center; padding: 56px 40px; border-radius: var(--radius-xl); background: var(--dark); color: #fff; }
.cta-box h2 { font-size: 1.6rem; font-weight: 800; letter-spacing: -.015em; margin-bottom: 10px; }
.cta-box p { color: rgba(255,255,255,.7); font-size: .95rem; margin-bottom: 24px; }
.cta-box .btn-primary { background: var(--primary); }

/* ===== Compare Table ===== */
.compare-table { width: 100%; border-collapse: collapse; font-size: .85rem; }
.compare-table th, .compare-table td { padding: 12px 16px; text-align: left; border-bottom: 1px solid var(--border-light); }
.compare-table thead th { font-weight: 700; font-size: .78rem; text-transform: uppercase; letter-spacing: .03em; color: var(--text-muted); background: var(--surface); }
.compare-table tbody tr:hover { background: var(--surface); }

/* ===== FAQ ===== */
.faq-item { border: 1px solid var(--border); border-radius: var(--radius-sm); margin-bottom: 10px; overflow: hidden; transition: all var(--transition); }
.faq-item[open] { border-color: var(--primary-soft); }
.faq-item > summary { font-weight: 600; padding: 16px 20px; cursor: pointer; list-style: none; display: flex; justify-content: space-between; align-items: center; font-size: .9rem; }
.faq-item > summary::-webkit-details-marker { display: none; }
.faq-item > summary::after { content: '+'; font-size: 1.2rem; color: var(--text-muted); transition: var(--transition); }
.faq-item[open] > summary::after { content: '−'; color: var(--primary); }
.faq-answer { padding: 0 20px 16px; font-size: .88rem; color: var(--text-secondary); line-height: 1.7; }

/* ===== Friend Links ===== */
.friend-links { margin-top: 40px; margin-bottom: 40px; padding-top: 32px; border-top: 1px solid var(--border-light); }
.friend-links h3 { font-size: .82rem; font-weight: 600; color: var(--text-muted); margin-bottom: 14px; text-transform: uppercase; letter-spacing: .04em; }
.friend-links-grid { display: flex; flex-wrap: wrap; gap: 8px; }
.friend-links-grid a { display: inline-block; padding: 6px 14px; border-radius: 100px; background: var(--surface); font-size: .78rem; color: var(--text-secondary); text-decoration: none; transition: all var(--transition); }
.friend-links-grid a:hover { background: var(--primary-light); color: var(--primary); }

/* ===== Footer ===== */
.footer { background: var(--dark); color: rgba(255,255,255,.7); padding: 56px 0 24px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-brand h3 { color: #fff; font-size: 1.15rem; font-weight: 800; margin-bottom: 8px; }
.footer-brand p { font-size: .85rem; line-height: 1.6; }
.footer-col h4 { color: #fff; font-size: .82rem; font-weight: 700; margin-bottom: 14px; text-transform: uppercase; letter-spacing: .04em; }
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 8px; }
.footer-col a { color: rgba(255,255,255,.6); font-size: .85rem; transition: color var(--transition); }
.footer-col a:hover { color: var(--primary); }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.1); padding-top: 20px; font-size: .78rem; color: rgba(255,255,255,.4); text-align: center; }

/* ===== Info Box ===== */
.info-box { padding: 16px 20px; border-radius: var(--radius-sm); background: var(--primary-light); border-left: 3px solid var(--primary); font-size: .88rem; color: var(--text-secondary); line-height: 1.7; }

/* ===== Scroll Top ===== */
#scrollTop { position: fixed; bottom: 28px; right: 28px; width: 42px; height: 42px; border-radius: 50%; background: var(--white); border: 1px solid var(--border); font-size: 1rem; cursor: pointer; display: none; align-items: center; justify-content: center; box-shadow: var(--shadow-sm); transition: all var(--transition); z-index: 90; color: var(--text-secondary); }
#scrollTop.visible { display: flex; }
#scrollTop:hover { background: var(--primary); color: #fff; border-color: var(--primary); }

/* ===== Modal ===== */
.modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,.35); backdrop-filter: blur(4px); z-index: 200; display: none; align-items: center; justify-content: center; }
.modal-overlay.active { display: flex; }
.modal { background: var(--white); border-radius: var(--radius-lg); padding: 40px; max-width: 400px; width: 90%; text-align: center; }
.modal-icon { font-size: 2.4rem; margin-bottom: 16px; }
.modal h3 { font-size: 1.15rem; font-weight: 700; margin-bottom: 8px; }
.modal p { font-size: .88rem; color: var(--text-secondary); margin-bottom: 24px; line-height: 1.6; }
.modal-actions { display: flex; gap: 10px; justify-content: center; }

/* ===== Fade In (渐进增强：默认可见，JS 失效不空白) ===== */
.fade-in { opacity: 1; }
.js .fade-in { opacity: 0; transform: translateY(16px); transition: opacity .5s ease, transform .5s ease; }
.js .fade-in.visible { opacity: 1; transform: translateY(0); }

/* ===== Utility Classes (外置内联 style) ===== */
.u-mb16 { margin-bottom: 16px; }
.u-mb20 { margin-bottom: 20px; }
.u-mb40 { margin-bottom: 40px; }
.u-mt12 { margin-top: 12px; }
.u-pb40 { padding-bottom: 40px; }
.u-max720 { max-width: 720px; margin: 0 auto; }
.u-prose18 { color: var(--text-secondary); font-size: .88rem; line-height: 1.8; }
.u-prose17 { color: var(--text-secondary); font-size: .88rem; line-height: 1.7; }
.u-prose17-mb { color: var(--text-secondary); font-size: .88rem; line-height: 1.7; margin-bottom: 12px; }
.u-prose2 { color: var(--text-secondary); font-size: .88rem; line-height: 2; }
.u-prose2-pl { color: var(--text-secondary); font-size: .88rem; line-height: 2; padding-left: 20px; }
.u-sum-pad { font-weight: 600; padding: 16px 20px; }
.u-h3-12 { font-size: 1rem; font-weight: 700; margin-bottom: 12px; }
.u-h3-10 { font-size: 1rem; font-weight: 700; margin-bottom: 10px; }
.u-h3-14 { font-size: 1rem; font-weight: 700; margin-bottom: 14px; }
.u-h3-6 { font-size: 1rem; font-weight: 700; margin-bottom: 6px; }
.u-h105-10 { font-size: 1.05rem; font-weight: 700; margin-bottom: 10px; }
.u-h105-12 { font-size: 1.05rem; font-weight: 700; margin-bottom: 12px; }
.u-h105-14 { font-size: 1.05rem; font-weight: 700; margin-bottom: 14px; }
.u-pri { color: var(--primary); }
.u-ok600 { color: var(--success); font-weight: 600; }
.u-ok700 { color: var(--success); font-weight: 700; }
.u-mut8-10 { color: var(--text-muted); font-size: .8rem; margin-top: 10px; }
.u-mut78 { color: var(--text-muted); font-size: .78rem; }
.u-flex-start { align-items: flex-start; display: flex; gap: 16px; }
.u-noshrink { flex-shrink: 0; }
.u-box-ct { margin-bottom: 20px; padding: 48px 32px; text-align: center; }
.u-ico28 { font-size: 2.8rem; margin-bottom: 14px; }
.u-pad1640 { font-size: 1rem; padding: 16px 40px; }
.u-cursor { cursor: pointer; }
.u-linkbox { background: var(--surface); border-radius: var(--radius-sm); border: 1px solid var(--border-light); color: inherit; display: block; padding: 16px; text-decoration: none; }
.u-quote { border-left: 3px solid var(--primary); margin-bottom: 12px; padding-left: 16px; }
.u-quote-nomb { border-left: 3px solid var(--primary); padding-left: 16px; }
.u-bare20 { border: none; padding: 20px; }
.u-grid3 { grid-template-columns: repeat(3, 1fr); }
.u-grid2 { display: grid; gap: 10px; grid-template-columns: repeat(2, 1fr); }
.u-cap-up { color: var(--primary); font-size: .88rem; font-weight: 700; letter-spacing: .04em; margin: 28px 0 14px; text-transform: uppercase; }
.u-cap-up2 { color: var(--primary); font-size: .88rem; font-weight: 700; letter-spacing: .04em; margin-bottom: 14px; text-transform: uppercase; }

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .feature-grid, .platform-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-row, .steps { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 640px) {
  .header-nav { display: none; }
  .menu-toggle { display: flex; }
  .hero { padding: 110px 0 56px; }
  .feature-grid, .stats-row, .steps, .platform-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 24px; }
  .hero-buttons { flex-direction: column; align-items: center; }
  .cta-box { padding: 40px 24px; }
}