#particles-js {
  background:
    radial-gradient(circle at 20% 20%, rgba(112, 86, 255, 0.28), transparent 30%),
    radial-gradient(circle at 80% 70%, rgba(36, 193, 255, 0.22), transparent 32%),
    #111827;
}

html[lang="zh"] [data-lang="en"]:not(.lang-btn),
html[lang="en"] [data-lang="zh"]:not(.lang-btn) {
  display: none;
}

.header {
  width: min(92%, 960px);
}

.lang-switch {
  position: fixed;
  top: 16px;
  right: 16px;
  z-index: 1000;
  display: inline-flex;
  gap: 4px;
  padding: 4px;
  border: 1px solid rgba(255, 255, 255, 0.34);
  border-radius: 999px;
  background: rgba(17, 24, 39, 0.82);
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.28);
  backdrop-filter: blur(8px);
}

.lang-btn {
  display: inline-block;
  min-width: 40px;
  padding: 6px 12px;
  border: none;
  border-radius: 999px;
  background: transparent;
  color: rgba(255, 255, 255, 0.72);
  font-family: inherit;
  font-size: 13px;
  font-weight: 600;
  line-height: 1;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}

.lang-btn:hover {
  color: #fff;
}

.lang-btn.active {
  background: #fff;
  color: #111827;
}

.header .site-title {
  letter-spacing: -0.06em;
}

.header .site-description {
  max-width: 780px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.25;
}

.header-links {
  margin-top: 22px;
}

.header-links .link {
  display: inline-flex;
  padding: 8px 14px;
  border: 1px solid rgba(255, 255, 255, 0.34);
  border-radius: 8px;
}

#about,
#projects {
  max-width: 1080px;
}

#about {
  padding: 80px 0 34px;
}

#projects {
  padding: 34px 0 30px;
}

.user-details {
  max-width: 780px;
}

.user-details h1 {
  margin: 0;
  padding-top: 0;
  color: #111827;
  letter-spacing: 0;
}

.user-details p {
  color: #5b6472;
  font-size: 17px;
  line-height: 1.8;
}

.user {
  gap: 18px;
  align-items: stretch;
  margin-top: 28px;
}

.tech {
  flex: 1;
  min-width: 220px;
  padding: 26px 22px;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  background: linear-gradient(180deg, #ffffff, #f8fafc);
  box-shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

.tech h2 {
  margin: 0 0 12px;
  padding-top: 0;
  color: #111827;
}

.tech p {
  color: #5b6472;
  line-height: 1.7;
}

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 30px;
}

.project-card {
  padding: 28px;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  background: #fff;
  box-shadow: 0 18px 45px rgba(15, 23, 42, 0.08);
}

.project-card.project-card-large {
  background:
    linear-gradient(135deg, rgba(30, 64, 175, 0.08), transparent 42%),
    #ffffff;
}

.project-card.accent {
  background:
    linear-gradient(135deg, rgba(5, 150, 105, 0.1), transparent 42%),
    #ffffff;
}

.project-card.warm {
  background:
    linear-gradient(135deg, rgba(217, 119, 6, 0.1), transparent 42%),
    #ffffff;
}

.project-card.callout {
  background: #111827;
  color: #fff;
}

.project-card h3 {
  margin: 6px 0 12px;
  padding-top: 0;
  color: inherit;
  letter-spacing: 0;
}

.project-card p {
  color: #5b6472;
  line-height: 1.75;
}

.project-card.callout p {
  color: rgba(255, 255, 255, 0.76);
}

.project-kicker {
  margin: 0 0 8px;
  color: #2563eb !important;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
}

.tag-list li {
  padding: 7px 11px;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  color: #111827;
  background: #f8fafc;
  font-size: 13px;
}

.project-link {
  margin-right: 10px;
  padding: 9px 14px;
  border-radius: 8px;
  border-color: #2563eb;
  color: #2563eb;
}

.project-link:hover,
.project-link:active {
  background-color: #2563eb;
  border-color: #2563eb;
}

.project-link.ghost {
  border-color: #d1d5db;
  color: #374151;
}

.project-card.callout .project-link.ghost {
  border-color: rgba(255, 255, 255, 0.44);
  color: #ffffff;
}

.project-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}

.project-actions .project-link {
  margin: 0;
}

.footer {
  margin-top: 70px;
}

@media only screen and (max-width: 720px) {
  .header .site-title {
    font-size: 54px;
  }

  .header .site-description {
    font-size: 22px;
  }

  .portfolio-grid {
    grid-template-columns: 1fr;
  }

  .project-actions .project-link {
    width: 100%;
  }
}