:root {
  --bg:#f7f7fb;
  --card:#fff;
  --text:#1f2a44;
  --muted:#4b5568;
  --hero-url: url('/hero-night.jpg');
}
body.day-theme { --hero-url: url('/hero-day.jpg'); }
body {
  margin:0;
  font-family:"Segoe UI", sans-serif;
  /* Use layered gradient over hero image for consistent overlay */
  background-image: linear-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.5)), var(--hero-url);
  background-repeat: no-repeat;
  background-position: center center;
  background-size: cover;
  /* fixed attachment can cause jank on mobile; enable only on large screens */
  background-attachment: fixed;
  color:var(--text);
  min-height: 100vh;
}

/* Improve mobile performance by disabling fixed background on small viewports */
@media (max-width: 1024px) {
  body { background-attachment: scroll; }
}
.theme-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  background: rgba(255, 255, 255, 0.9);
  border: none;
  padding: 10px 14px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 18px;
  z-index: 100;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  transition: all 0.3s ease;
}
.theme-toggle:hover { background: rgba(255, 255, 255, 1); transform: scale(1.1); }

h1 { margin:0 0 8px; font-size:26px; color:#fff; }
p { margin:0; line-height:1.5; color:rgba(255,255,255,0.9); }
.toplist-title { margin:0 0 6px; font-weight:700; font-size:14px; text-transform:uppercase; letter-spacing:0.4px; color:rgba(255,255,255,0.85); }
ol { margin:0; padding-left:20px; color:rgba(255,255,255,0.9); }
ol li { margin:2px 0; }

/* Use case glass card (top-right) - shared across stack pages */
.usecase-card {
  position: fixed;
  top: 20px;
  right: 20px;
  padding: 12px 14px;
  background: rgba(255,255,255,0.10);
  border: 1px solid rgba(255,255,255,0.22);
  border-radius: 12px;
  color: #e6e6e6;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.15);
  max-width: 320px;
  z-index: 10000;
  pointer-events: auto;
}

/* Home button shared across stack pages */
.home-btn {
  position: fixed;
  top: 20px;
  left: 20px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.22);
  background: rgba(255,255,255,0.10);
  color: #e6e6e6;
  text-decoration: none;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.15);
  transition: all 0.2s ease;
  z-index: 100;
  font-size: 14px;
}

.home-btn:hover {
  background: rgba(255, 255, 255, 0.15);
  transform: translateX(-2px);
}

@media (max-width: 768px) {
  .home-btn {
    position: static;
    width: fit-content;
    margin: 12px 6px 6px;
  }
  
  .usecase-card {
    position: static;
    width: auto;
    max-width: 100%;
    margin: 6px 6px 12px;
  }
}
.usecase-card .uc-title {
  font-weight: 700;
  font-size: 14px;
  margin-bottom: 6px;
  color: rgba(255,255,255,0.9);
  text-transform: uppercase;
  letter-spacing: 0.4px;
}
.usecase-card .uc-line {
  font-size: 13px;
  margin: 2px 0;
}
.usecase-card .label {
  color: rgba(255,255,255,0.85);
  font-weight: 600;
}

/* Prevent horizontal overflow on small devices */
html, body {
  max-width: 100%;
  overflow-x: hidden;
}

/* Make common media elements responsive */
img, svg, video, iframe {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Prevent wide code blocks or tables from forcing horizontal scroll */
pre, code, table {
  max-width: 100%;
  overflow: auto;
  white-space: pre-wrap;
  word-break: break-word;
}

/* Site-wide mobile-first layout rules so all pages are responsive */
.page-grid {
  display: block;
  width: 100%;
  box-sizing: border-box;
  padding: 12px;
}

/* Panels and cards should be fluid by default */
.panel, .card, .api-section, .stacks-panel, .content-panel, .architecture-bar { width: 100%; box-sizing: border-box; }

/* Make lane elements stack/wrap on narrow screens */
.lane-inner { display:flex; flex-wrap:wrap; gap:10px; overflow-x:visible; }
.topic-card { width: 100%; box-sizing: border-box; }

/* Web & Networking: single column by default */
.web-network-panel .wn-grid { grid-template-columns: 1fr; gap: 10px; }

/* Theme toggle smaller on phones */
.theme-toggle { top: 12px; right: 12px; padding: 8px; }

/* Restore desktop layout at wider widths */
@media (min-width: 961px) {
  .page-grid { display: grid; grid-template-columns: 320px 1fr; grid-template-areas: "api api" "stacks content" "architecture architecture" "footer footer"; gap: 12px; max-width: 1200px; margin: 0 auto; }
  .lane-inner { flex-wrap: nowrap; overflow-x:auto; }
  .topic-card { width: 160px; }
  .web-network-panel .wn-grid { grid-template-columns: repeat(3, minmax(160px, 1fr)); }
}