:root {
  --navy-deep: #0b2648;
  --navy: #0d3b66;
  --blue: #3a7bd5;
  --gold: #f7a600;
  --gold-light: #ffcb3d;
  --green: #0f4d27;
  --green-light: #1f7a3f;
  --text-dark: #17233a;
  --text-muted: #5a6a7e;
  --bg-light: #f7f9fb;
  --white: #ffffff;
  --shadow: 0 10px 30px rgba(11, 38, 72, 0.12);
  --radius: 12px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--text-dark);
  background: var(--white);
  line-height: 1.6;
}

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

.container {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px;
}

a { text-decoration: none; color: inherit; }

h1, h2, h3 { margin: 0 0 16px; line-height: 1.25; }

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(6px);
  box-shadow: 0 2px 12px rgba(11, 38, 72, 0.08);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding-top: 12px;
  padding-bottom: 12px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.brand-logo {
  width: 44px;
  height: 44px;
  object-fit: contain;
  border-radius: 6px;
}

.brand-name {
  display: flex;
  flex-direction: column;
  line-height: 1.15;
}

.brand-en {
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.5px;
  color: var(--navy-deep);
}

.brand-zh {
  font-size: 12px;
  color: var(--text-muted);
}

.main-nav {
  display: flex;
  gap: 32px;
  flex: 1;
  justify-content: center;
}

.main-nav a {
  font-weight: 600;
  font-size: 15px;
  color: var(--text-dark);
  padding: 6px 2px;
  border-bottom: 2px solid transparent;
  transition: border-color 0.2s, color 0.2s;
}

.main-nav a:hover {
  color: var(--navy);
  border-bottom-color: var(--gold);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.lang-switch {
  display: flex;
  border: 1px solid #d8e0ea;
  border-radius: 999px;
  overflow: hidden;
}

.lang-btn {
  border: none;
  background: transparent;
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-muted);
  transition: background 0.2s, color 0.2s;
}

.lang-btn.active {
  background: var(--navy);
  color: var(--white);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 34px;
  height: 34px;
  border: none;
  background: none;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--navy-deep);
  border-radius: 2px;
}

/* Hero */
.hero {
  position: relative;
  min-height: 86vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  color: var(--white);
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-size: cover;
  background-position: center;
  transform: scale(1.02);
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(11, 38, 72, 0.55) 0%, rgba(11, 38, 72, 0.35) 45%, rgba(11, 38, 72, 0.75) 100%);
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 720px;
  padding-top: 60px;
  padding-bottom: 60px;
}

.hero-content h1 {
  font-size: clamp(32px, 5vw, 52px);
  font-weight: 800;
  text-shadow: 0 2px 16px rgba(0, 0, 0, 0.35);
}

.hero-content p {
  font-size: 17px;
  color: rgba(255, 255, 255, 0.92);
  margin-bottom: 32px;
  max-width: 560px;
}

.btn {
  display: inline-block;
  padding: 14px 32px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 15px;
  cursor: pointer;
  border: none;
  transition: transform 0.15s, box-shadow 0.15s;
}

.btn-primary {
  background: linear-gradient(135deg, var(--gold-light), var(--gold));
  color: var(--navy-deep);
  box-shadow: 0 8px 24px rgba(247, 166, 0, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(247, 166, 0, 0.45);
}

/* Section shared */
section { padding: 90px 0; }

.section-subtitle {
  color: var(--text-muted);
  font-size: 16px;
  max-width: 620px;
  margin-top: -8px;
  margin-bottom: 48px;
}

/* Projects */
.projects { background: var(--bg-light); }

.project-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 28px;
}

.project-card {
  background: var(--white);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform 0.2s, box-shadow 0.2s;
}

.project-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 40px rgba(11, 38, 72, 0.18);
}

.project-card img {
  width: 100%;
  aspect-ratio: 8 / 5;
  object-fit: cover;
}

.project-card-body { padding: 20px 22px 26px; }

.tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  color: var(--green-light);
  background: rgba(31, 122, 63, 0.1);
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 12px;
}

.project-card h3 {
  font-size: 19px;
  color: var(--navy-deep);
}

.project-card p {
  font-size: 14.5px;
  color: var(--text-muted);
  margin: 0;
}

/* Contact */
.contact {
  background: var(--navy-deep);
  color: var(--white);
}

.contact .section-subtitle { color: rgba(255, 255, 255, 0.75); }

.contact-inner {
  display: grid;
  grid-template-columns: 1fr 1.4fr;
  gap: 48px;
  align-items: start;
}

.contact-email-label {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: rgba(255, 255, 255, 0.6);
  margin-bottom: 6px;
}

.contact-email {
  font-size: 24px;
  font-weight: 700;
  color: var(--gold-light);
  word-break: break-all;
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 14px;
  background: rgba(255, 255, 255, 0.05);
  padding: 28px;
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 13px 16px;
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  background: rgba(255, 255, 255, 0.08);
  color: var(--white);
  font-size: 15px;
  font-family: inherit;
  resize: vertical;
}

.contact-form input::placeholder,
.contact-form textarea::placeholder {
  color: rgba(255, 255, 255, 0.5);
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--gold);
}

.contact-form .btn { align-self: flex-start; }

.form-note {
  color: var(--gold-light);
  font-weight: 600;
  margin: 0;
}

/* Footer */
.site-footer {
  background: #081b33;
  color: rgba(255, 255, 255, 0.6);
  padding: 24px 0;
  font-size: 13px;
  text-align: center;
}

/* Responsive */
@media (max-width: 860px) {
  .contact-inner {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 760px) {
  .main-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    align-items: center;
    gap: 0;
    max-height: 0;
    overflow: hidden;
    box-shadow: 0 12px 20px rgba(11, 38, 72, 0.1);
    transition: max-height 0.25s ease;
  }

  .main-nav.open {
    max-height: 260px;
  }

  .main-nav a {
    width: 100%;
    text-align: center;
    padding: 16px;
    border-bottom: 1px solid #eef1f5;
  }

  .nav-toggle { display: flex; }

  .brand-en { font-size: 13px; }
  .brand-zh { font-size: 11px; }

  section { padding: 60px 0; }
}