:root {
  --bg: #F4F8FB;
  --primary: #4A77B1;
  --muted: #5C6975;
  --card: #FFFFFF;
  --max-width: 980px;
}

/* Reset */

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

html,
body {
  width: 100%;
  height: 100%;
}

body {
  font-family: 'Noto Sans SC', 'Inter', 'Microsoft Yahei', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--bg);
  color: #333333;
}

html[lang="zh-CN"] body {
  font-family: "Noto Serif SC", "Noto Serif", "Times New Roman", serif;
  font-weight: 300;
}


/* =========================
   Top Navigation (over hero)
   ========================= */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding: 24px 40px;
  background-color: transparent; /* overlay on hero */
  border-bottom: none;
  transition:
    background-color 0.3s ease,
    border-color 0.3s ease,
    padding 0.3s ease,
    color 0.3s ease;
}

.site-brand a {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
  color: #ffffff;
  font-size: 28px;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
}

.site-title-text {
  line-height: 1;
}

.site-nav {
  display: flex;
  gap: 32px;
  font-size: 14px;
  margin-top: 0px;
  margin-right: 20px;
  letter-spacing: 0.20em;
  text-transform: uppercase;
}

.site-nav a {
  text-decoration: none;
  color: #ffffff;
  padding: 2px 0;
  transition: color 0.2s ease;
}

.site-nav a:hover {
  color: #d0e4ff;
}

.site-header-right {
  display: flex;
  align-items: center;
  margin-top: 2px;
  gap: 0;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-right: 8px;
  font-size: 16px;
  letter-spacing: 0.01em;
  text-transform: none;
  color: #ffffff;
  font-family: "Noto Serif", "Noto Serif SC", "Times New Roman", serif;
  font-weight: 400;
}

.lang-switch-handle {
  text-align: right;
  font-size: 0.95em;
}

.lang-switch-handle a {
  background: none;
  border: none;
  padding: 0 0 4px;
  font: inherit;
  color: inherit !important;
  cursor: pointer;
  border-bottom: 3px solid transparent;
  text-decoration: none !important;
}

.lang-switch-handle a:visited,
.lang-switch-handle a:hover,
.lang-switch-handle a:active {
  color: inherit !important;
}

.lang-switch-handle a.active {
  border-bottom-color: #f2d400 !important;
}

.lang-switch-handle a:focus-visible {
  outline: 2px solid #f2d400;
  outline-offset: 2px;
}

.lang-sep {
  color: currentColor;
  opacity: 0.6;
}

/* Solid, compact header after hero */

.site-header.scrolled {
  background-color: rgba(244, 248, 251, 0.98);
  border-bottom: 1px solid rgba(34, 34, 34, 0.06);
  padding: 14px 24px;
}

.site-header.scrolled .site-brand a {
  color: #222222;
  font-size: 18px;
  letter-spacing: 0.16em;
}

.site-header.scrolled .site-nav a {
  color: var(--muted);
}

.site-header.scrolled .site-nav a:hover {
  color: var(--primary);
}

.site-header.scrolled .lang-switch {
  color: #222222;
}

.site-header.scrolled .lang-switch-handle .active {
  color: inherit;
}

.site-header.scrolled .lang-sep {
  color: currentColor;
  opacity: 0.6;
}

/* Mobile nav toggle */

.nav-toggle {
  display: none;
  border: none;
  background: transparent;
  padding: 0;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  cursor: pointer;
  color: #ffffff;
}

/* =========================
   Full-screen Hero with Video
   ========================= */

.hero-full {
  position: relative;
  width: 100%;
  height: 100vh;           /* full viewport */
  overflow: hidden;
  display: flex;
  align-items: flex-end;
  justify-content: flex-start;
  padding: 40px;
  color: #ffffff;
  /* Fallback image if video fails to load */
  background:
    linear-gradient(
      to bottom,
      rgba(0, 0, 0, 0.38) 0%,
      rgba(0, 0, 0, 0.38) 40%,
      rgba(0, 0, 0, 0.78) 100%
    ),
    url("../image/boat.png") center center / cover no-repeat;
}

/* Video covers entire hero */

.hero-video {
  position: absolute;
  top: 50%;
  left: 50%;
  min-width: 100%;
  min-height: 100%;
  transform: translate(-50%, -50%);
  object-fit: cover;
  z-index: 0;
}

/* Dark overlay for readability */

.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    rgba(0, 0, 0, 0.35),
    rgba(0, 0, 0, 0.8)
  );
  z-index: 1;
}

/* Hero text */

.hero-content {
  position: relative;
  max-width: var(--max-width);
  z-index: 2;
}

.hero-kicker {
  font-size: 14px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  margin-bottom: 6px;
}

.hero-title {
  font-size: 40px;
  font-weight: 400;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin: 0 0 10px;
}

.hero-subtitle {
  font-size: 18px;
  margin: 0 0 12px;
  opacity: 0.95;
}

.hero-caption {
  font-size: 13px;
  max-width: 420px;
  opacity: 0.9;
}

/* Scroll-down icon */

.scroll-down {
  position: relative;
  z-index: 2;
  position: absolute;
  right: 40px;
  bottom: 36px;
  width: 32px;
  height: 32px;
  border-radius: 999px;
  border: 1px solid #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  color: #ffffff;
  font-size: 16px;
  opacity: 0.9;
  transition: background-color 0.2s ease, transform 0.2s ease, opacity 0.2s ease;
}

.scroll-down:hover {
  background-color: rgba(255, 255, 255, 0.14);
  transform: translateY(2px);
  opacity: 1;
}

/* =========================
   Main Content
   ========================= */

#content {
  width: 100%;
  max-width: var(--max-width);
  margin: 40px auto 36px;
  padding: 20px;
}

.paragraph {
  background: linear-gradient(
    180deg,
    rgba(255, 255, 255, 0.98),
    var(--card)
  );
  border-radius: 14px;
  box-shadow: 0 6px 18px rgba(40, 60, 80, 0.08);
  margin-bottom: 18px;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.paragraph:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 20px rgba(40, 60, 80, 0.12);
}

.paragraph h3 {
  font-weight: 600;
  font-size: 24px;
  padding: 22px 20px 6px;
  color: var(--primary);
  text-align: left;
}

.paragraph p {
  padding: 0 20px 22px;
  color: var(--muted);
  line-height: 1.8;
  font-size: 15px;
}

/* =========================
   Footer
   ========================= */

#footer {
  width: 100%;
  padding: 24px 0;
  border-top: 1px solid rgba(34, 34, 34, 0.04);
  background: transparent;
}

#footer span {
  display: block;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
}

/* =========================
   Back-to-top Button
   ========================= */

#to-top {
  position: fixed;
  right: 28px;
  bottom: 28px;
  width: 52px;
  height: 52px;
  border-radius: 10px;
  background: linear-gradient(180deg, #ffffff, #f3f7fa);
  box-shadow: 0 6px 18px rgba(40, 60, 80, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  opacity: 0;
  transform: translateY(16px);
  transition: all 0.25s ease;
}

#to-top.show {
  opacity: 1;
  transform: none;
}

#to-top::after {
  content: "↑";
  font-weight: 700;
  color: var(--primary);
}

/* =========================
   Responsive
   ========================= */

@media (max-width: 720px) {
  .site-header {
    padding: 18px 16px;
  }

  .lang-switch {
    display: none;
  }

  .nav-toggle {
    display: inline-block;
  }

  .site-nav {
    position: fixed;
    top: 56px;
    right: 0;
    flex-direction: column;
    gap: 10px;
    padding: 10px 18px 14px;
    background-color: rgba(0, 0, 0, 0.9);
    display: none;
  }

  .site-nav.is-open {
    display: flex;
  }

  .site-header.scrolled .nav-toggle {
    color: #222222;
  }

  .hero-title {
    font-size: 30px;
  }

  .hero-subtitle {
    font-size: 16px;
  }

  .hero-full {
    padding: 26px 18px 32px;
  }

  #content {
    padding: 12px;
    margin-top: 26px;
  }

  .paragraph h3 {
    font-size: 20px;
  }
}