/* ============================================================
   USTradeStack — 2026 Design System (global.css)
   ============================================================
   Foundation styles: palette, typography, spacing, components.
   Every page links this file for consistent visual identity.
   ============================================================ */

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

/* --- CSS Custom Properties (Design Tokens) --- */
:root {
  /* Palette */
  --navy:        #0F1B2D;
  --navy-light:  #1E293B;
  --red:         #DC2626;
  --red-hover:   #B91C1C;
  --white:       #FFFFFF;
  --bg-light:    #F8FAFC;
  --text-primary:#0F172A;
  --text-secondary:#64748B;
  --text-tertiary:#94A3B8;
  --border:      #E2E8F0;
  --border-light:#F1F5F9;
  --green:       #16A34A;
  --amber:       #D97706;

  /* Typography */
  --font:        'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono:   'SF Mono', 'Fira Code', 'Fira Mono', 'Roboto Mono', monospace;

  /* Spacing (4px base) */
  --space-1:  4px;
  --space-2:  8px;
  --space-3:  12px;
  --space-4:  16px;
  --space-5:  20px;
  --space-6:  24px;
  --space-8:  32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  --space-20: 80px;
  --space-24: 96px;

  /* Radii */
  --radius-sm:  6px;
  --radius-md:  8px;
  --radius-lg:  12px;
  --radius-xl:  16px;

  /* Shadows */
  --shadow-sm:   0 1px 2px rgba(15,23,42,0.04);
  --shadow-md:   0 4px 12px rgba(15,23,42,0.06);
  --shadow-lg:   0 8px 24px rgba(15,23,42,0.08);
  --shadow-card: 0 1px 3px rgba(15,23,42,0.04), 0 1px 2px rgba(15,23,42,0.02);

  /* Layout */
  --max-width: 1280px;
}

/* --- Base --- */
html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--white);
  color: var(--text-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.6;
}

a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }

/* --- Container --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-8);
}

/* --- Section Spacing --- */
.section { padding: var(--space-24) 0; }
.section-sm { padding: var(--space-16) 0; }
.section-lg { padding: 120px 0; }

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 { font-weight: 700; line-height: 1.15; letter-spacing: -0.02em; color: var(--text-primary); }
h1 { font-size: clamp(36px, 5vw, 64px); letter-spacing: -0.03em; }
h2 { font-size: clamp(28px, 3.5vw, 44px); }
h3 { font-size: 20px; }
h4 { font-size: 17px; }
p { color: var(--text-secondary); line-height: 1.65; }

.section-label {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--red);
  margin-bottom: var(--space-4);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 44px;
  padding: 0 20px;
  border-radius: var(--radius-md);
  font-family: var(--font);
  font-size: 15px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
  white-space: nowrap;
}
.btn-primary {
  background: var(--red);
  color: var(--white);
}
.btn-primary:hover {
  background: var(--red-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(220,38,38,0.25);
}
.btn-secondary {
  background: var(--white);
  color: var(--navy);
  border: 1.5px solid var(--border);
}
.btn-secondary:hover {
  border-color: var(--navy);
  background: var(--bg-light);
}
.btn-lg {
  height: 52px;
  padding: 0 28px;
  font-size: 16px;
  border-radius: var(--radius-md);
}

/* --- Cards --- */
.card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-card);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
.card:hover {
  box-shadow: var(--shadow-md);
  border-color: #CBD5E1;
}
.card-interactive {
  cursor: pointer;
}
.card-interactive:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* --- Badge --- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 100px;
  font-size: 13px;
  font-weight: 500;
}
.badge-red {
  background: rgba(220,38,38,0.08);
  color: var(--red);
  border: 1px solid rgba(220,38,38,0.15);
}
.badge-green {
  background: rgba(22,163,74,0.08);
  color: var(--green);
  border: 1px solid rgba(22,163,74,0.15);
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  transition: box-shadow 0.3s ease;
}
.site-nav.scrolled {
  box-shadow: var(--shadow-sm);
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-8);
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}
.nav-logo-icon {
  flex-shrink: 0;
}
.nav-logo-text {
  font-weight: 500;
  font-size: 17px;
  color: var(--text-primary);
  letter-spacing: -0.3px;
}
.nav-logo-text .us {
  font-weight: 700;
  color: var(--navy);
}
.nav-logo-text .accent {
  font-weight: 700;
  color: var(--red);
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav-link {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  transition: color 0.15s, background 0.15s;
}
.nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-light);
}
.nav-cta {
  display: inline-flex;
  align-items: center;
  height: 38px;
  padding: 0 18px;
  background: var(--red);
  color: var(--white);
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: background 0.2s;
  margin-left: 8px;
}
.nav-cta:hover {
  background: var(--red-hover);
}

/* Mobile hamburger */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  z-index: 110;
}
.nav-hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}
.nav-hamburger.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-hamburger.active span:nth-child(2) { opacity: 0; }
.nav-hamburger.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile menu overlay */
.nav-mobile-menu {
  display: none;
  position: fixed;
  top: 64px;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--white);
  z-index: 99;
  padding: var(--space-6);
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}
.nav-mobile-menu.open {
  display: flex;
}
.nav-mobile-menu a {
  display: block;
  padding: 14px 16px;
  font-size: 16px;
  font-weight: 500;
  color: var(--text-primary);
  border-radius: var(--radius-md);
  transition: background 0.15s;
}
.nav-mobile-menu a:hover {
  background: var(--bg-light);
}
.nav-mobile-menu .mobile-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 48px;
  margin-top: var(--space-4);
  background: var(--red);
  color: var(--white);
  font-weight: 600;
  border-radius: var(--radius-md);
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  background: var(--bg-light);
  border-top: 1px solid var(--border);
  padding: var(--space-16) 0 var(--space-8);
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-8);
}
.footer-top {
  display: flex;
  justify-content: space-between;
  gap: var(--space-12);
  margin-bottom: var(--space-12);
}
.footer-brand-col {
  max-width: 280px;
  flex-shrink: 0;
}
.footer-brand-name {
  font-size: 17px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-3);
}
.footer-brand-name .accent { color: var(--red); }
.footer-brand-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
}
.footer-nav-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-8);
  flex: 1;
}
.footer-col-head {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-primary);
  margin-bottom: var(--space-3);
}
.footer-col-links {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-col-links a {
  font-size: 14px;
  color: var(--text-secondary);
  transition: color 0.15s;
}
.footer-col-links a:hover {
  color: var(--text-primary);
}
.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: var(--space-6);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-3);
}
.footer-legal-links {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
  justify-content: center;
}
.footer-legal-links a {
  font-size: 13px;
  color: var(--text-tertiary);
  transition: color 0.15s;
}
.footer-legal-links a:hover { color: var(--text-secondary); }
.footer-legal-links .sep { color: var(--border); }
.footer-disclaimer {
  font-size: 12px;
  color: var(--text-tertiary);
  text-align: center;
  max-width: 720px;
  line-height: 1.6;
}
.footer-disclaimer a {
  color: var(--text-secondary);
  text-decoration: underline;
  text-underline-offset: 2px;
}

/* ============================================================
   ALERT BANNER (top of page)
   ============================================================ */
.alert-banner {
  background: #FEF3C7;
  color: var(--text-primary);
  padding: 10px var(--space-8);
  font-size: 13px;
  font-weight: 500;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
  border-bottom: 1px solid #FDE68A;
}
.alert-banner a {
  color: var(--red);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 2px;
}
.alert-banner-dismiss {
  background: none;
  border: none;
  font-size: 18px;
  cursor: pointer;
  color: var(--text-tertiary);
  margin-left: 16px;
  line-height: 1;
  padding: 0;
  flex-shrink: 0;
}
.alert-banner-dismiss:hover { color: var(--text-primary); }
body.has-alert-banner .site-nav { top: 40px; }
body.has-alert-banner .hero { padding-top: 168px; }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 1024px) {
  .footer-nav-grid { grid-template-columns: repeat(2, 1fr); gap: var(--space-8) var(--space-10); }
}

@media (max-width: 768px) {
  .container { padding: 0 var(--space-5); }
  .section { padding: var(--space-16) 0; }
  .section-lg { padding: var(--space-20) 0; }

  /* Nav mobile */
  .nav-links { display: none; }
  .nav-cta.desktop-only { display: none; }
  .nav-hamburger { display: flex; }

  /* Footer */
  .footer-top { flex-direction: column; gap: var(--space-8); }
  .footer-brand-col { max-width: 100%; }
  .footer-nav-grid { grid-template-columns: repeat(2, 1fr); gap: var(--space-6) var(--space-8); }
}

@media (max-width: 480px) {
  .footer-nav-grid { grid-template-columns: 1fr; }
  h1 { font-size: clamp(30px, 8vw, 44px); }
}