/*
  Binance-like responsive theme (no external assets)
  - Color system, spacing scale, layout grid, utilities
  - Mobile-first; breakpoints: 640, 960, 1200
*/

:root {
  --bg: #ffffff;
  --bg-elev: #ffffff;
  --text: #0b1220;
  --muted: #6b7280;
  --brand: #111827;
  --accent: #f3ba2f;
  --line: #e5e7eb;

  --radius: 12px;
  --shadow: 0 6px 24px rgba(0,0,0,.25);

  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-7: 28px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  --max-w: 1200px;
}

/* Reset & base */
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}
a { color: var(--brand); text-decoration: none; }
a:hover { opacity: .8; }
img { max-width: 100%; display: block; }

.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--space-4);
}

.grid {
  display: grid;
  gap: var(--space-6);
}

.cards-3 { grid-template-columns: 1fr; }

@media (min-width: 640px) {
  .cards-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .cards-3 { grid-template-columns: repeat(3, 1fr); }
}

/* Accessibility */
.skip-link {
  position: absolute; left: -9999px; top: -9999px;
}
.skip-link:focus {
  left: var(--space-4);
  top: var(--space-4);
  background: var(--brand);
  color: #000;
  padding: var(--space-2) var(--space-4);
  border-radius: 6px;
}
/* Header */
.site-header {
  background: #000000;
}

.nav-container {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-4);
  align-items: center;
  padding: var(--space-2) var(--space-4);
}

.hamburger {
  grid-column: 3;
  justify-self: end;
}

.logo { display: inline-flex; align-items: center; margin: -8px 0; }
.logo-img { height: 56px; width: auto; display: block; }

.nav-toggle { display: none; }
.hamburger { 
  width: 32px; 
  height: 28px; 
  display: inline-flex; 
  flex-direction: column; 
  justify-content: center; 
  gap: 5px; 
  cursor: pointer;
  padding: 8px;
  border-radius: 6px;
  transition: background .2s ease;
}
.hamburger:hover { background: #222; }
.hamburger span { 
  display: block; 
  height: 2px; 
  background: #ffffff; 
  border-radius: 2px;
  transition: all .3s ease;
}

#nav-toggle:checked ~ label.hamburger span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
#nav-toggle:checked ~ label.hamburger span:nth-child(2) {
  opacity: 0;
}
#nav-toggle:checked ~ label.hamburger span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.main-nav { display: none; }
.main-nav ul { 
  list-style: none; 
  margin: 0; 
  padding: 0; 
  display: flex; 
  flex-direction: column;
  gap: 0;
}
.main-nav li { border-bottom: 1px solid #333; }
.main-nav li:last-child { border-bottom: none; }
.main-nav a { 
  color: #ffffff; 
  padding: var(--space-4) var(--space-3); 
  border-radius: 0;
  display: block;
  transition: background .2s ease;
}
.main-nav a:hover { background: #222; }

.nav-actions { display: none; gap: var(--space-3); }

/* Show menu when toggled */
#nav-toggle:checked ~ .main-nav { 
  display: block; 
  grid-column: 1 / -1; 
  background: #000000;
  border-top: 1px solid #333;
  margin-top: var(--space-4);
  padding: var(--space-2) 0;
  animation: slideDown .3s ease;
}
#nav-toggle:checked ~ .nav-actions { 
  display: flex; 
  grid-column: 1 / -1; 
  padding: var(--space-4) 0;
  border-top: 1px solid #333;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (min-width: 960px) {
  .hamburger { display: none; }
  .main-nav { display: block; }
  .main-nav ul { flex-direction: row; gap: var(--space-4); }
  .main-nav li { border-bottom: none; }
  .main-nav a { padding: var(--space-2) var(--space-3); border-radius: 6px; }
  .nav-actions { display: flex; justify-self: end; }
}

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; border: 1px solid transparent; border-radius: 8px; padding: 10px 14px; font-weight: 600; cursor: pointer; transition: transform .02s ease, background .2s ease, color .2s ease; }
.btn:active { transform: translateY(1px); }
.btn-gray { background: #f3f4f6; color: var(--brand); border-color: #f3f4f6; }
.btn-gray:hover { background: #e5e7eb; border-color: #e5e7eb; }
.btn-yellow { background: #f3ba2f; color: #000000; border-color: #f3ba2f; }
.btn-yellow:hover { background: #d9a617; border-color: #d9a617; }
.site-header .btn-gray { background: #333; color: #ffffff; border-color: #333; }
.site-header .btn-gray:hover { background: #444; border-color: #444; }
.site-header .btn-yellow { background: #f3ba2f; color: #000000; border-color: #f3ba2f; }
.site-header .btn-yellow:hover { background: #d9a617; border-color: #d9a617; }
.btn-lg { padding: 12px 18px; }

.muted { color: var(--muted); }

/* Sections */
.section { padding: var(--space-16) 0; }
.section-head { margin-bottom: var(--space-8); }
.section-head h2 { margin: 0 0 var(--space-2); font-size: 24px; color: var(--brand); }
.section-sub { margin: 0; color: var(--muted); }

/* Hero */
.hero { background: linear-gradient(180deg, #ffffff, #fafafa); }
.hero-grid { grid-template-columns: 1fr; align-items: center; }
.hero-title { font-size: 32px; margin: 0 0 var(--space-3); color: var(--brand); }
.hero-sub { margin: 0 0 var(--space-5); color: var(--muted); }
.hero-ctas { display: flex; gap: var(--space-4); flex-direction: column; }
.hero-ctas .btn { width: 100%; min-width: 200px; }
.hero-img { width: 100%; max-width: 280px; height: auto; display: block; margin: 0 auto; }

@media (min-width: 960px) {
  .hero-grid { grid-template-columns: 1.2fr 1fr; }
  .hero-title { font-size: 40px; }
  .hero-ctas { flex-direction: row; }
  .hero-ctas .btn { width: auto; }
}

/* Advantages Section */
.advantages { background: #fafafa; border-top: 1px solid var(--line); }
.advantages .section-head { text-align: center; }
.adv-card { 
  background: #ffffff; 
  border: 1px solid var(--line); 
  border-radius: var(--radius); 
  padding: var(--space-8) var(--space-6); 
  text-align: center;
  transition: all .3s ease;
}
.adv-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0,0,0,.1);
  border-color: var(--accent);
}
.adv-card h3 { 
  font-size: 20px; 
  margin: 0 0 var(--space-4); 
  color: var(--brand);
  font-weight: 700;
}
.adv-card p { 
  font-size: 15px; 
  line-height: 1.7; 
  color: var(--muted); 
  margin: 0; 
}

/* Feature Sections */
.feature { background: #fff; }
.feature-reverse { background: #fff; }
.feature-grid { 
  display: grid; 
  grid-template-columns: 1fr; 
  gap: var(--space-8); 
  align-items: center; 
}
.feature-grid .feature-content { order: 1; }
.feature-grid .feature-image { order: 2; }
.feature-content h2 { 
  font-size: 28px; 
  margin: 0 0 var(--space-4); 
  color: var(--brand); 
}
.feature-desc { 
  font-size: 16px; 
  line-height: 1.7; 
  color: var(--muted); 
  margin: 0 0 var(--space-6); 
}
.feature-list { 
  list-style: none; 
  padding: 0; 
  margin: 0 0 var(--space-6); 
  display: grid; 
  gap: var(--space-3); 
}
.feature-list li { 
  font-size: 15px; 
  color: var(--text); 
}
.feature-image { 
  width: 100%;
  overflow: hidden;
}
.feature-image img,
.feature-image video { 
  width: 100%; 
  height: auto; 
  display: block;
  object-fit: cover;
  transform: scale(1.02);
}

@media (min-width: 960px) {
  .feature-grid { grid-template-columns: 1fr 1fr; gap: var(--space-12); }
  .feature-reverse .feature-grid { grid-template-columns: 1fr 1fr; }
  .feature-grid .feature-content { order: 0; }
  .feature-grid .feature-image { order: 0; }
  .feature-reverse .feature-image { order: -1; }
  .feature-content h2 { font-size: 32px; }
}

/* FAQ */
.faq-item { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: var(--space-4) var(--space-6); margin-bottom: var(--space-4); }
.faq-item summary { cursor: pointer; font-weight: 700; }
.faq-content { margin-top: var(--space-3); color: var(--muted); }

/* CTA */
.cta { 
  background-color: #fafafa;
  background-position: center center;
  background-repeat: no-repeat;
  background-size: 60% auto;
  position: relative;
}
.cta::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(250, 250, 251, 0.7);
  pointer-events: none;
}
.cta-inner { 
  position: relative;
  z-index: 1;
  display: flex; 
  flex-direction: column; 
  align-items: center; 
  text-align: center; 
  gap: var(--space-4); 
}
.cta-inner h2 { margin: 0; }
.cta-buttons { 
  display: flex; 
  gap: var(--space-4); 
  margin-top: var(--space-4);
  flex-wrap: wrap;
  justify-content: center;
}
@media (max-width: 640px) {
  .cta-buttons { 
    flex-direction: column; 
    width: 100%;
  }
  .cta-buttons .btn { width: 100%; }
}

/* Footer */
.site-footer { border-top: 1px solid var(--line); padding: var(--space-12) 0 var(--space-8); background: #ffffff; }
.footer-grid { display: grid; gap: var(--space-8); grid-template-columns: 1fr; }
.footer-col h3 { margin: 0 0 var(--space-4); font-size: 16px; font-weight: 600; color: var(--brand); }
.footer-col ul { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; }
.footer-links { 
  padding: var(--space-6) 0; 
  margin-top: var(--space-8); 
  border-top: 1px solid var(--line); 
  font-size: 14px;
  line-height: 1.8;
}
.flink-title { 
  font-weight: 600; 
  color: var(--brand);
}
.footer-links a { 
  color: var(--muted); 
  transition: color .2s ease;
}
.footer-links a:hover { 
  color: var(--accent); 
}

@media (min-width: 640px) {
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .footer-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (min-width: 1200px) {
  .footer-grid { grid-template-columns: repeat(6, 1fr); }
}

/* Utilities */
.hero-right { display: block; }