/* ============================================================
   layout.css — CSS Grid site shell, header, sidebar
   ============================================================ */

/* ── App shell ──────────────────────────────────────────────── */
.app-shell {
  display: grid;
  grid-template-columns: 1fr;
  grid-template-rows: auto auto 1fr;
  grid-template-areas:
    "header"
    "nav"
    "main";
  min-height: 100dvh;
}

@media (min-width: 720px) {
  .app-shell {
    grid-template-columns: 220px 1fr;
    grid-template-rows: auto 1fr;
    grid-template-areas:
      "header header"
      "nav    main";
  }
}

@media (min-width: 1100px) {
  .app-shell {
    grid-template-columns: 260px 1fr;
    max-width: 1280px;
    margin-inline: auto;
    width: 100%;
  }
}

/* Full-bleed wrapper to constrain max-width on desktop */
.app-shell-wrap {
  background-color: var(--color-bg);
  min-height: 100dvh;
}
@media (min-width: 1100px) {
  .app-shell-wrap {
    display: flex;
    justify-content: center;
    padding-inline: var(--space-5);
  }
}

/* ── Site header ────────────────────────────────────────────── */
.site-header {
  grid-area: header;
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background-color: var(--color-bg-elevated);
  /* Fallback for browsers without color-mix */
  background-color: rgba(255, 255, 255, 0.93);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-3) var(--space-4);
  display: flex;
  align-items: baseline;
  gap: var(--space-3);
  /* Thin accent line at very top of header */
  border-top: 2px solid var(--color-accent);
}

@media (prefers-color-scheme: dark) {
  .site-header {
    background-color: rgba(19, 23, 20, 0.93);
  }
}

.site-header__brand {
  font-family: var(--font-sans);
  font-size: var(--fs-display);
  font-weight: var(--fw-bold);
  letter-spacing: var(--tracking-tight);
  color: var(--color-accent);
  text-decoration: none;
  line-height: 1;
}
.site-header__brand:visited { color: var(--color-accent); }
.site-header__brand:hover,
.site-header__brand:visited:hover {
  color: var(--color-accent-hover);
  text-decoration: none;
}

.site-header__tagline {
  font-size: var(--fs-sm);
  color: var(--color-text-subtle);
  font-style: italic;
}

.site-header__env-badge {
  font-family: var(--font-sans);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 999px;
  line-height: 1;
  /* default: dev */
  background-color: var(--color-env-dev);
  color: #fff;
}
.site-header__env-badge--test {
  background-color: var(--color-env-test);
  color: #fff;
}

/* ── Mobile nav toggle (checkbox + hamburger label) ─────────── */
.nav-toggle-input {
  /* Visually hidden but still togglable via its <label> */
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

/* Remove from tab order and accessibility tree on desktop where it isn't used */
@media (min-width: 720px) {
  .nav-toggle-input { display: none; }
}

/* Proxy focus ring to the visible hamburger button for keyboard users */
.nav-toggle-input:focus-visible ~ .site-header .nav-toggle-btn {
  box-shadow: var(--shadow-focus);
}

.nav-toggle-btn {
  display: none; /* shown only on mobile via media query below */
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  margin-left: auto;
  align-self: center;
  flex-shrink: 0;
  cursor: pointer;
  border-radius: var(--radius-md);
  -webkit-tap-highlight-color: transparent;
  transition: background-color var(--dur-fast) var(--ease-out);
}
.nav-toggle-btn:hover {
  background-color: var(--color-surface-hover);
}
.nav-toggle-btn span {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--color-text-muted);
  border-radius: 2px;
  transform-origin: center;
  transition:
    transform var(--dur-med) var(--ease-out),
    opacity var(--dur-fast) var(--ease-out),
    background-color var(--dur-fast) var(--ease-out);
}

/* ── Sidebar / side nav ─────────────────────────────────────── */
.side-nav {
  grid-area: nav;
  background-color: var(--color-bg);
  border-right: 1px solid var(--color-border);
  padding: var(--space-5) var(--space-4);
  overflow-y: auto;
}

/* ── Mobile: hamburger visible, nav collapsed ───────────────── */
@media (max-width: 719px) {
  .nav-toggle-btn { display: flex; }

  .side-nav {
    display: none;
    border-right: none;
    border-bottom: 1px solid var(--color-border);
    background-color: var(--color-bg-elevated);
    padding: var(--space-4);
    box-shadow: var(--shadow-sm);
  }

  /* Show nav when checkbox is checked */
  .nav-toggle-input:checked ~ .side-nav {
    display: block;
    animation: nav-slide-in 220ms var(--ease-out) both;
  }

  /* Hamburger → X morph */
  .nav-toggle-input:checked ~ .site-header .nav-toggle-btn span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
    background-color: var(--color-text);
  }
  .nav-toggle-input:checked ~ .site-header .nav-toggle-btn span:nth-child(2) {
    opacity: 0;
    transform: scaleX(0.1);
  }
  .nav-toggle-input:checked ~ .site-header .nav-toggle-btn span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
    background-color: var(--color-text);
  }
}

@keyframes nav-slide-in {
  from { opacity: 0; transform: translateY(-6px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Main content ───────────────────────────────────────────── */
.main-content {
  grid-area: main;
  min-width: 0; /* prevent grid blowout on narrow viewports */
  padding: var(--space-5) var(--space-4);
}

/* ── Container (page-width limit) ──────────────────────────── */
.container {
  max-width: 1040px;
  margin-inline: auto;
}

/* ── Prose (long-form text measure) ────────────────────────── */
.prose {
  max-width: var(--measure);
  line-height: var(--lh-relaxed);
  font-family: var(--font-sans);
  font-size: var(--fs-md);
  color: var(--color-text);
}
.prose p { max-width: none; line-height: var(--lh-relaxed); }
.prose p + p { margin-top: var(--space-4); }
.prose > * + * { margin-top: var(--space-3); }

/* ── Page heading with border ───────────────────────────────── */
.page-heading {
  font-size: var(--fs-2xl);
  font-weight: var(--fw-bold);
  letter-spacing: var(--tracking-tight);
  color: var(--color-heading);
  margin-bottom: var(--space-5);
  padding-bottom: var(--space-3);
  border-bottom: 2px solid var(--color-border);
}