:root {
  --bg: #ffffff;
  --surface: #1f77b4;
  --text: #171717;
  --text-muted: #6b6b6b;
  --border: #e5e5e5;
  --grad-start: #ffff00;
  --grad-end: #ff0000;

  --font-display: "DejaVu Sans", Verdana, Arial, sans-serif;
  --font-body: "DejaVu Sans", Verdana, Arial, sans-serif;
  --font-mono: "DejaVu Sans", Verdana, Arial, sans-serif;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }

/* ---------- Nav ---------- */

.site-nav {
  background: var(--surface);
  padding: 1.1rem 1.5rem;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.site-nav .brand {
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 400;
  color: #fff;
  text-decoration: none;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.site-nav .links {
  display: flex;
  gap: 1.5rem;
}

.site-nav .links a {
  color: #eaf3fa;
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: border-color 0.15s ease;
}

.site-nav .links a:hover,
.site-nav .links a.active {
  border-bottom-color: var(--grad-start);
}

/* ---------- Layout ---------- */

main {
  max-width: 980px;
  margin: 0 auto;
  padding: 2.5rem 1.5rem 5rem;
}

.gradient-rule {
  height: 4px;
  width: 72px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--grad-start), var(--grad-end));
  margin: 0.9rem 0 2rem;
}

/* ---------- Period toggle ---------- */

.period-toggle {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.period-toggle button {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  background: #fff;
  border: 1.5px solid var(--border);
  color: var(--text-muted);
  padding: 0.5rem 1rem;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.15s ease;
}

.period-toggle button:hover {
  border-color: var(--text-muted);
  color: var(--text);
}

.period-toggle button.active {
  background: var(--surface);
  border-color: transparent;
  color: #fff;
  font-weight: 600;
}

/* ---------- Period nav (prev/next arrows + total) ---------- */

.period-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.nav-group {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.period-nav #period-label {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--text);
  min-width: 12ch;
  text-align: center;
}

.period-total {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--text);
}

.nav-arrow {
  background: #fff;
  border: 1.5px solid var(--border);
  color: var(--text);
  font-size: 1.2rem;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 50%;
  cursor: pointer;
  transition: border-color 0.15s ease;
  line-height: 1;
}

.nav-arrow:hover:not(:disabled) {
  border-color: var(--text);
}

.nav-arrow:disabled {
  opacity: 0.3;
  cursor: default;
}

/* ---------- Chart card ---------- */

.chart-card {
  border-radius: 10px;
}

.chart-card.has-canvas {
  padding: 0.6rem 1.25rem 1.5rem;
  aspect-ratio: 1560 / 720;
}

#day-image {
  width: 100%;
  aspect-ratio: 1560 / 720;
  object-fit: contain;
  border-radius: 6px;
  display: block;
}

.chart-card canvas {
  width: 100% !important;
  height: 100% !important;
}

/* ---------- Section headings ---------- */

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: -0.01em;
}

h1 { font-size: 2.1rem; margin: 0 0 0.25rem; }
h2 { font-size: 1.4rem; margin: 2.5rem 0 0.75rem; }

p { line-height: 1.6; color: var(--text); }

.lede {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 60ch;
}

/* ---------- Gallery ---------- */

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
}

.gallery-item {
  cursor: pointer;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border);
  transition: transform 0.15s ease;
}

.gallery-item:hover {
  transform: translateY(-3px);
}

.gallery-item img {
  width: 100%;
  display: block;
}

.gallery-item .caption {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  padding: 0.5rem 0.75rem 0.7rem;
  display: flex;
  justify-content: space-between;
}

/* ---------- Lightbox ---------- */

.lightbox-overlay {
  position: fixed;
  inset: 0;
  background: rgba(10, 20, 30, 0.92);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 100;
  flex-direction: column;
  padding: 2rem;
}

.lightbox-overlay.open { display: flex; }

.lightbox-overlay img {
  max-width: min(90vw, 1100px);
  max-height: 75vh;
  border-radius: 8px;
}

.lightbox-caption {
  color: #fff;
  font-family: var(--font-mono);
  margin-top: 1rem;
  font-size: 0.95rem;
}

.lightbox-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  color: #fff;
  font-size: 2.5rem;
  cursor: pointer;
  padding: 0.5rem 1rem;
  opacity: 0.7;
  transition: opacity 0.15s ease;
  font-family: var(--font-body);
}

.lightbox-nav:hover { opacity: 1; }
.lightbox-nav.prev { left: 0.5rem; }
.lightbox-nav.next { right: 0.5rem; }

.lightbox-close {
  position: absolute;
  top: 1.25rem;
  right: 1.5rem;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.75rem;
  cursor: pointer;
  opacity: 0.7;
}

.lightbox-close:hover { opacity: 1; }

/* ---------- About page ---------- */

.about-block {
  margin-bottom: 2rem;
}

.spec-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  margin: 1rem 0;
}

.spec-table td {
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
}

.spec-table td:first-child {
  color: var(--text-muted);
  width: 40%;
}

/* ---------- Footer ---------- */

/* ---------- Responsive ---------- */

@media (max-width: 600px) {
  .site-nav { flex-direction: column; align-items: flex-start; }

  .chart-card.has-canvas {
    aspect-ratio: 4 / 3;
  }

  .nav-arrow {
    width: 2.75rem;
    height: 2.75rem;
    font-size: 1.4rem;
  }
}

/* ---------- Accessibility ---------- */

a:focus-visible,
button:focus-visible {
  outline: 2px solid #0a5a8a;
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  * {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
  .gallery-item:hover {
    transform: none;
  }
}