/* Mountain Xie — mountainxie.com | Brand: PRD ch.4 — #0A0A0A / #F97316 / Inter */
/* 字体通过各页面 <head> 的 preconnect + link 加载（非阻塞），不在CSS里@import */

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

:root {
  --black:  #0A0A0A;
  --dark:   #111827;
  --mid:    #1F2937;
  --orange: #F97316;
  --orange-dark: #ea6a0a;
  --gray:   #6B7280;
  --light:  #D1D5DB;
  --white:  #FFFFFF;
  --border: rgba(255,255,255,0.08);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  background: var(--black);
  color: var(--white);
  line-height: 1.65;
  overflow-x: hidden;
}

a { color: var(--orange); }
img { max-width: 100%; display: block; }

/* ── NAV ── */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 48px;
  background: rgba(10,10,10,0.88);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}
.nav-logo { font-size: 18px; font-weight: 800; letter-spacing: -0.5px; color: var(--white); text-decoration: none; }
.nav-logo span { color: var(--orange); }
.nav-links { display: flex; gap: 28px; align-items: center; }
.nav-links a { color: var(--light); text-decoration: none; font-size: 14px; font-weight: 500; transition: color .2s; }
.nav-links a:hover { color: var(--white); }
.nav-cta {
  background: var(--orange); color: var(--black) !important;
  padding: 10px 20px; border-radius: 8px; font-weight: 700 !important;
}
.nav-cta:hover { background: var(--orange-dark) !important; }
.nav-toggle { display: none; background: none; border: 1px solid var(--border); color: var(--white); font-size: 20px; padding: 4px 12px; border-radius: 8px; cursor: pointer; }

/* ── LAYOUT ── */
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 48px; }
section { padding: 88px 0; }
.section-dark { background: var(--dark); }

/* ── HERO ── */
.hero {
  min-height: 88vh;
  display: flex; flex-direction: column; justify-content: center;
  padding-top: 140px; padding-bottom: 60px;
  background:
    radial-gradient(ellipse 60% 50% at 72% 45%, rgba(249,115,22,0.08) 0%, transparent 70%),
    var(--black);
}
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px; width: fit-content;
  background: rgba(249,115,22,0.1); border: 1px solid rgba(249,115,22,0.25);
  color: var(--orange); font-size: 12px; font-weight: 600;
  letter-spacing: 1.5px; text-transform: uppercase;
  padding: 6px 14px; border-radius: 99px; margin-bottom: 28px;
}
h1 {
  font-size: clamp(40px, 6vw, 76px);
  font-weight: 900; line-height: 1.05; letter-spacing: -2px;
  max-width: 860px; margin-bottom: 22px;
}
h1 .accent { color: var(--orange); }
.hero-sub {
  font-size: clamp(16px, 2vw, 20px); color: var(--light);
  max-width: 580px; margin-bottom: 40px; line-height: 1.7;
}

/* Stats bar */
.stats-bar {
  display: flex; border: 1px solid var(--border); border-radius: 16px;
  overflow: hidden; max-width: 720px; margin-bottom: 40px;
  background: rgba(255,255,255,0.02);
}
.stat-item { flex: 1; padding: 22px 16px; text-align: center; border-right: 1px solid var(--border); }
.stat-item:last-child { border-right: none; }
.stat-num { font-size: clamp(24px, 3vw, 36px); font-weight: 800; color: var(--orange); letter-spacing: -1px; }
.stat-label { font-size: 12px; color: var(--gray); text-transform: uppercase; letter-spacing: 1px; margin-top: 4px; }
.stat-note { font-size: 11.5px; color: var(--light); margin-top: 6px; line-height: 1.4; }

/* CTA */
.cta-row { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; margin-bottom: 18px; }
.btn-primary {
  display: inline-block;
  background: var(--orange); color: var(--black); text-decoration: none;
  font-weight: 700; font-size: 16px; padding: 16px 32px; border-radius: 10px;
  transition: background .2s, transform .15s;
}
.btn-primary:hover { background: var(--orange-dark); transform: translateY(-1px); }
.btn-secondary { color: var(--white); text-decoration: none; font-weight: 600; font-size: 15px; }
.btn-secondary:hover { color: var(--orange); }
.trust-line { font-size: 13.5px; color: var(--gray); }
.cta-note { font-size: 13px; color: var(--gray); margin-top: 10px; }

/* ── SECTION HEADERS ── */
h2 { font-size: clamp(28px, 4vw, 44px); font-weight: 800; letter-spacing: -1px; line-height: 1.15; margin-bottom: 16px; }
h3 { font-size: 20px; font-weight: 700; margin-bottom: 10px; }
.section-intro { color: var(--light); font-size: 17px; max-width: 640px; margin-bottom: 48px; }
p { margin-bottom: 16px; }

/* ── CARDS ── */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
.card {
  background: var(--dark); border: 1px solid var(--border); border-radius: 16px;
  padding: 32px 28px; transition: border-color .2s, transform .15s;
}
.card:hover { border-color: rgba(249,115,22,0.4); transform: translateY(-2px); }
.card-icon { font-size: 30px; margin-bottom: 16px; }
.card h3 { color: var(--white); }
.card p, .card li { color: var(--light); font-size: 15px; }
.card ul { list-style: none; margin: 14px 0; }
.card li { padding: 5px 0 5px 22px; position: relative; }
.card li::before { content: '→'; position: absolute; left: 0; color: var(--orange); }
.card-link { display: inline-block; margin-top: 8px; color: var(--orange); text-decoration: none; font-weight: 600; font-size: 14.5px; }
.card-link:hover { text-decoration: underline; }

/* ── TABLES ── */
table { width: 100%; border-collapse: collapse; margin: 24px 0; font-size: 15px; }
th, td { padding: 13px 16px; text-align: left; border-bottom: 1px solid var(--border); }
th { color: var(--orange); font-weight: 700; font-size: 13px; text-transform: uppercase; letter-spacing: .8px; }
td { color: var(--light); }
td strong { color: var(--white); }
.table-scroll { overflow-x: auto; }

/* ── PROSE (blog/about/faq) ── */
.prose { max-width: 760px; }
.prose h2 { font-size: 28px; margin-top: 48px; }
.prose h3 { margin-top: 28px; }
.prose p, .prose li { color: var(--light); font-size: 16.5px; }
.prose ul, .prose ol { margin: 0 0 16px 22px; }
.prose blockquote {
  border-left: 3px solid var(--orange); padding: 4px 0 4px 20px;
  margin: 24px 0; color: var(--white); font-style: italic;
}
.post-meta { color: var(--gray); font-size: 14px; margin-bottom: 32px; }

/* ── FAQ ── */
.faq-item { border-bottom: 1px solid var(--border); padding: 6px 0; }
.faq-item summary {
  cursor: pointer; font-weight: 600; font-size: 16.5px; color: var(--white);
  padding: 16px 0; list-style: none; position: relative; padding-right: 36px;
}
.faq-item summary::after { content: '+'; position: absolute; right: 4px; color: var(--orange); font-size: 22px; font-weight: 400; }
.faq-item[open] summary::after { content: '–'; }
.faq-item div { color: var(--light); font-size: 15.5px; padding: 0 0 18px; max-width: 760px; }

/* ── CASE STUDY ── */
.case { border: 1px solid var(--border); border-radius: 16px; padding: 36px; margin-bottom: 28px; background: var(--dark); }
.case-outcome { color: var(--orange); font-weight: 700; font-size: 18px; margin-bottom: 18px; }
.case h3 { font-size: 22px; }
.case .label { font-size: 12px; text-transform: uppercase; letter-spacing: 1.2px; color: var(--gray); font-weight: 700; margin: 20px 0 6px; }
.case p, .case li { color: var(--light); font-size: 15.5px; }
.case ul { list-style: none; }
.case li { padding: 4px 0 4px 22px; position: relative; }
.case li::before { content: '→'; position: absolute; left: 0; color: var(--orange); }

/* ── COMPARISON ── */
.check { color: #34d399; } .cross { color: var(--gray); }

/* ── PHOTO ── */
.portrait { border-radius: 16px; border: 1px solid var(--border); max-width: 380px; }

/* ── CTA BANNER ── */
.cta-banner {
  background: linear-gradient(135deg, rgba(249,115,22,0.12), rgba(249,115,22,0.04));
  border: 1px solid rgba(249,115,22,0.3); border-radius: 20px;
  padding: 56px 48px; text-align: center;
}
.cta-banner h2 { margin-bottom: 12px; }
.cta-banner p { color: var(--light); max-width: 520px; margin: 0 auto 28px; }

/* ── FOOTER ── */
footer { border-top: 1px solid var(--border); padding: 48px; text-align: center; color: var(--gray); font-size: 14px; }
footer a { color: var(--light); text-decoration: none; margin: 0 10px; }
footer a:hover { color: var(--orange); }
.footer-tag { margin-top: 10px; font-size: 13px; }

/* ── RESPONSIVE ── */
@media (max-width: 860px) {
  nav { padding: 14px 20px; }
  .nav-links { display: none; position: absolute; top: 100%; left: 0; right: 0;
    background: #0A0A0A; flex-direction: column; padding: 24px 20px 28px; gap: 18px;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 24px 48px rgba(0,0,0,0.85); }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; }
  .wrap { padding: 0 20px; }
  section { padding: 56px 0; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .stats-bar { flex-wrap: wrap; }
  .stat-item { flex: 1 1 50%; border-bottom: 1px solid var(--border); }
  .cta-banner { padding: 40px 24px; }
}
