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

html, body {
  width: 100%;
  height: 100%;
  background-color: #f8fafc;
  background-image: radial-gradient(circle at 50% 0%, #ffffff 0%, #f1f5f9 100%);
  color: #0f172a;
  font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* --------------------------------------------------------------------------
   Navigation View (Light Minimal Theme)
   -------------------------------------------------------------------------- */
#nav-view {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 48px 24px;
  transition: opacity 0.25s ease, transform 0.25s ease;
}

#nav-view.view-hidden {
  opacity: 0;
  transform: scale(0.98);
  pointer-events: none;
  display: none;
}

/* Projects Showcase Grid */
.projects-grid {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 32px;
  max-width: 1200px;
  width: 100%;
}

/* Project Card - Light Style */
.project-card {
  width: 340px;
  background: #ffffff;
  border: 1px solid rgba(0, 0, 0, 0.08);
  border-radius: 18px;
  padding: 14px;
  cursor: pointer;
  box-shadow: 0 4px 20px -2px rgba(0, 0, 0, 0.05), 0 2px 6px -1px rgba(0, 0, 0, 0.02);
  transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1), 
              box-shadow 0.25s cubic-bezier(0.16, 1, 0.3, 1), 
              border-color 0.25s ease;
  display: flex;
  flex-direction: column;
}

.project-card:hover {
  transform: translateY(-6px);
  border-color: rgba(0, 0, 0, 0.16);
  box-shadow: 0 20px 35px -5px rgba(0, 0, 0, 0.1), 0 8px 16px -3px rgba(0, 0, 0, 0.04);
}

/* Live Effect Preview Poster */
.card-preview-box {
  width: 100%;
  height: 200px;
  border-radius: 12px;
  overflow: hidden;
  position: relative;
  border: 1px solid rgba(0, 0, 0, 0.06);
}

.card-preview-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

.project-card:hover .card-preview-img {
  transform: scale(1.04);
}

/* Title only - clean, refined, light-theme typography */
.project-title {
  margin-top: 14px;
  font-size: 0.98rem;
  font-weight: 600;
  color: #334155;
  text-align: center;
  letter-spacing: -0.01em;
  transition: color 0.2s ease;
}

.project-card:hover .project-title {
  color: #0f172a;
}

/* --------------------------------------------------------------------------
   Full-Screen Preview View
   -------------------------------------------------------------------------- */
#preview-view {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  z-index: 1000;
  background: #000000;
  opacity: 1;
  visibility: visible;
  transition: opacity 0.3s ease, visibility 0.3s ease;
}

#preview-view.preview-hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

#preview-frame {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: none;
  background: #000000;
}

/* --------------------------------------------------------------------------
   Top-Left Faint Return Arrow ONLY (无背景色，仅悬浮微亮返回键)
   -------------------------------------------------------------------------- */
.btn-back {
  position: fixed;
  top: 22px;
  left: 24px;
  z-index: 10005;
  background: transparent !important;
  border: none !important;
  box-shadow: none !important;
  outline: none;
  padding: 6px;
  margin: 0;
  cursor: pointer;
  color: rgba(255, 255, 255, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color 0.2s ease, transform 0.2s ease;
  filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.8));
}

.btn-back:hover {
  color: #ffffff;
  transform: translateX(-3px);
}

@media (max-width: 768px) {
  .projects-grid {
    flex-direction: column;
    gap: 20px;
  }
  .project-card {
    width: 90vw;
    max-width: 360px;
  }
  .btn-back {
    top: 16px;
    left: 16px;
  }
}