/* ============================================================
   Vast River — Computer Systems Design
   Changchun Haochuanyun Technology Co., Ltd.
   ============================================================ */

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

:root {
  --ink:       #111316;
  --slate:     #1c1f26;
  --charcoal:  #262a33;
  --steel:     #3b404d;
  --mist:      #6b7080;
  --silver:    #a3a9b6;
  --cloud:     #d6d9e0;
  --frost:     #ecedf2;
  --cream:     #f7f5f0;
  --paper:     #fafaf8;
  --white:     #ffffff;

  --amber:     #c6933a;
  --amber-dim: #a87a2a;
  --gold:      #d4a853;
  --gold-pale: #e8d5a3;
  --bronze:    #8b6914;

  --font-body: 'Inter', 'Noto Sans SC', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Cascadia Code', 'Fira Code', monospace;

  --max-w:     1200px;
  --radius:    6px;
}

html {
  scroll-behavior: smooth;
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body {
  font-family: var(--font-body);
  background: var(--ink);
  color: var(--frost);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--gold); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--gold-pale); }

img, svg { display: block; max-width: 100%; }

/* --- Typography ------------------------------------------- */
h1, h2, h3, h4 { line-height: 1.25; font-weight: 600; letter-spacing: -0.015em; }
h1 { font-size: clamp(2.6rem, 5.5vw, 4.2rem); }
h2 { font-size: clamp(1.7rem, 3vw, 2.3rem); }
h3 { font-size: 1.25rem; }

.section-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 0.6rem;
}

.page-title {
  color: var(--white);
  border-bottom: 2px solid var(--amber-dim);
  padding-bottom: 0.6rem;
  margin-bottom: 1.8rem;
}

.text-muted { color: var(--silver); }
.text-amber { color: var(--amber); }

/* --- Layout ----------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.6rem;
}

main { flex: 1; }

/* --- Header / Nav ----------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--ink);
  border-bottom: 1px solid var(--charcoal);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.2rem;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.6rem;
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--white);
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
}
.logo-link:hover { color: var(--gold); }

.logo-mark {
  width: 36px;
  height: 36px;
  background: var(--amber);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink);
  font-weight: 800;
  font-size: 1.1rem;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 0.3rem;
}

.nav-links a {
  display: block;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  color: var(--silver);
  font-size: 0.92rem;
  font-weight: 500;
  transition: color 0.2s, background 0.2s;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--gold);
  background: var(--charcoal);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.4rem;
  color: var(--silver);
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}
.nav-toggle span + span { margin-top: 5px; }

.nav-open .nav-toggle span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.nav-open .nav-toggle span:nth-child(2) { opacity: 0; }
.nav-open .nav-toggle span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* --- Footer ----------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--charcoal);
  background: var(--slate);
  margin-top: 5rem;
  padding: 3rem 0 1.5rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 2.5rem;
  margin-bottom: 2.5rem;
}

.footer-branding .logo-link { font-size: 1.05rem; margin-bottom: 0.6rem; }
.footer-branding .logo-mark { width: 30px; height: 30px; font-size: 0.9rem; }
.footer-branding p { color: var(--mist); font-size: 0.88rem; max-width: 26ch; }

.footer-col h4 {
  color: var(--white);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.9rem;
}
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 0.45rem; }
.footer-col a { color: var(--silver); font-size: 0.9rem; }
.footer-col a:hover { color: var(--gold); }

.footer-bottom {
  border-top: 1px solid var(--charcoal);
  padding-top: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--steel);
  font-size: 0.82rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

/* --- Hero ------------------------------------------------- */
.hero {
  padding: 6rem 0 4rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -60%;
  left: 50%;
  transform: translateX(-50%);
  width: 900px;
  height: 900px;
  background: radial-gradient(ellipse at center, var(--amber-dim) 0%, transparent 70%);
  opacity: 0.06;
  pointer-events: none;
}

.hero h1 {
  color: var(--white);
  margin-bottom: 1rem;
  position: relative;
}

.hero .subtitle {
  font-size: 1.25rem;
  color: var(--silver);
  max-width: 38rem;
  margin: 0 auto 2.2rem;
  font-weight: 400;
}

.hero .accent-line {
  display: block;
  width: 64px;
  height: 3px;
  background: var(--amber);
  margin: 0 auto 2.2rem;
  border-radius: 2px;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.8rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: 0.01em;
  cursor: pointer;
  border: none;
  transition: background 0.25s, color 0.25s, transform 0.15s;
}
.btn:active { transform: scale(0.97); }

.btn-primary {
  background: var(--amber);
  color: var(--ink);
}
.btn-primary:hover {
  background: var(--gold);
  color: var(--ink);
}

.btn-ghost {
  background: transparent;
  color: var(--gold);
  border: 1.5px solid var(--steel);
}
.btn-ghost:hover {
  border-color: var(--gold);
  color: var(--gold-pale);
}

.hero-actions { display: flex; gap: 0.8rem; justify-content: center; flex-wrap: wrap; }

/* --- Sections --------------------------------------------- */
.section {
  padding: 5rem 0;
}

.section-header {
  text-align: center;
  margin-bottom: 3.5rem;
}
.section-header h2 {
  color: var(--white);
  margin-bottom: 0.6rem;
}
.section-header p {
  color: var(--silver);
  max-width: 36rem;
  margin: 0 auto;
}

/* --- Services Grid ---------------------------------------- */
.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.service-card {
  background: var(--slate);
  border: 1px solid var(--charcoal);
  border-radius: var(--radius);
  padding: 2rem 1.6rem;
  transition: border-color 0.3s, transform 0.2s;
  position: relative;
  overflow: hidden;
}
.service-card:hover {
  border-color: var(--steel);
  transform: translateY(-2px);
}
.service-card::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--amber);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.35s;
}
.service-card:hover::after { transform: scaleX(1); }

.service-icon {
  width: 48px;
  height: 48px;
  background: var(--charcoal);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1.2rem;
  color: var(--amber);
}

.service-card h3 {
  color: var(--white);
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
}
.service-card p {
  color: var(--silver);
  font-size: 0.92rem;
  line-height: 1.6;
}

/* --- About ------------------------------------------------- */
.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3.5rem;
  align-items: center;
}

.about-text h2 { color: var(--white); margin-bottom: 1rem; }
.about-text p {
  color: var(--silver);
  margin-bottom: 1rem;
}

.about-visual {
  background: var(--slate);
  border: 1px solid var(--charcoal);
  border-radius: var(--radius);
  padding: 2.5rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}

.stat-box {
  text-align: center;
  padding: 1.2rem 1rem;
  background: var(--charcoal);
  border-radius: var(--radius);
}
.stat-box .stat-number {
  font-size: 2rem;
  font-weight: 700;
  color: var(--amber);
  letter-spacing: -0.02em;
}
.stat-box .stat-label {
  font-size: 0.78rem;
  color: var(--silver);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-top: 0.2rem;
}

/* --- Contact ---------------------------------------------- */
.contact-card {
  background: var(--slate);
  border: 1px solid var(--charcoal);
  border-radius: var(--radius);
  padding: 3rem;
  max-width: 640px;
  margin: 0 auto;
}

.contact-row {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.2rem;
}
.contact-row:last-child { margin-bottom: 0; }
.contact-icon {
  width: 40px;
  height: 40px;
  flex-shrink: 0;
  background: var(--charcoal);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--amber);
  font-size: 1.1rem;
}
.contact-row strong {
  display: block;
  color: var(--white);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.15rem;
}
.contact-row span, .contact-row a {
  color: var(--silver);
  font-size: 0.95rem;
}

/* --- Policy Pages ----------------------------------------- */
.policy-content {
  max-width: 780px;
  margin: 0 auto;
  padding: 3rem 0 4rem;
}

.policy-content h2 {
  color: var(--white);
  font-size: 1.3rem;
  margin: 2.4rem 0 0.8rem;
}
.policy-content h2:first-of-type { margin-top: 0; }

.policy-content p {
  color: var(--silver);
  margin-bottom: 1rem;
  line-height: 1.7;
}

.policy-content ul {
  color: var(--silver);
  margin: 0.5rem 0 1.2rem 1.4rem;
}
.policy-content li { margin-bottom: 0.4rem; line-height: 1.6; }

.policy-content .effective-date {
  color: var(--mist);
  font-size: 0.88rem;
  margin-bottom: 2rem;
  font-style: italic;
}

.policy-content address {
  color: var(--silver);
  font-style: normal;
  line-height: 1.7;
  margin: 0.8rem 0 1.2rem;
}

/* --- Animations ------------------------------------------- */
.fade-in {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Responsive ------------------------------------------- */
@media (max-width: 768px) {
  .nav-toggle { display: block; }

  .nav-links {
    position: absolute;
    top: 4.2rem;
    left: 0;
    right: 0;
    background: var(--slate);
    border-bottom: 1px solid var(--charcoal);
    flex-direction: column;
    padding: 0.6rem 1rem 1rem;
    display: none;
  }
  .nav-open .nav-links { display: flex; }

  .about-content { grid-template-columns: 1fr; gap: 2rem; }
  .footer-grid { grid-template-columns: 1fr; gap: 2rem; }
  .footer-bottom { flex-direction: column; text-align: center; }
  .hero { padding: 4rem 0 2.5rem; }
  .section { padding: 3rem 0; }
  .contact-card { padding: 2rem 1.4rem; }
}

@media (max-width: 480px) {
  .about-visual { grid-template-columns: 1fr; }
  .hero h1 { font-size: 2.2rem; }
}