/* Issue #1061 — Bottom navigation styles.
 *
 * Activates at viewports ≤768px. Uses position:fixed so it does not
 * trigger layout reflow on the rest of the page, plus
 * env(safe-area-inset-bottom) padding so the iOS home-indicator does
 * not overlap the tabs. The matching <meta viewport-fit=cover> already
 * exists in index.html (verified pre-implementation).
 *
 * Tokens reused (defined in BOTH :root and dark @media in style.css):
 *   --nav-bg, --nav-text, --nav-text-muted, --nav-active-bg, --accent,
 *   --border, --space-sm.
 *
 * Decision: media query (not container query). The rest of the codebase
 * uses @media exclusively (no @container rules in style.css today), so
 * a media query keeps things consistent.
 *
 * Decision: top-nav suppression = display:none at ≤768px. Spec
 * forbids duplicate nav UX; the bottom nav covers the 5 high-priority
 * routes; long-tail routes (Tools/Lab/Perf/Analytics/etc.) remain
 * reachable by URL. A "More" tab or hamburger fallback is deferred per
 * the issue body's explicit guidance.
 */

/* #1174 mesh-op review: --bottom-nav-reserve is the contract page-level
 * full-viewport rules use to subtract the bottom-nav's height from
 * 100dvh. 0px at desktop (no nav reserved); 56px + safe-area at ≤768px.
 * Pages opt-in by referencing it (see public/live.css for /live, and
 * #app.app-fixed in style.css for the SPA fixed-page container). */
:root {
  --bottom-nav-reserve: 0px;
}

/* Default: hidden on wide viewports. The bottom-nav element exists in
 * the DOM at all widths (build runs at DOMContentLoaded) but is only
 * rendered to the user at ≤768px. */
.bottom-nav {
  display: none;
}

@media (max-width: 768px) {
  /* #1174 mesh-op review: set the reserve token at the breakpoint so
   * page-level full-viewport rules (e.g. .live-page, #app.app-fixed)
   * automatically subtract the bottom-nav height. */
  :root {
    --bottom-nav-reserve: calc(56px + env(safe-area-inset-bottom, 0px));
  }

  .bottom-nav {
    display: flex;
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1200; /* above nav-links dropdown (1100) */
    background: var(--nav-bg);
    border-top: 1px solid var(--border);
    box-shadow: 0 -4px 16px rgba(0, 0, 0, 0.25);
    /* env() falls back to 0 outside iOS notch devices. We also keep
     * a small minimum so the rule resolves to a non-empty value. */
    padding-bottom: env(safe-area-inset-bottom, 0px);
    padding-top: 0;
    /* Distribute 5 tabs evenly. */
    justify-content: space-around;
    align-items: stretch;
    /* No transform — would create a stacking context that traps any
     * fixed-position descendants (we have none, but cheap insurance). */
  }

  /* Suppress the inline link bar and right-side cluster — but KEEP
   * .nav-brand (logo identity). #1174: also hide #hamburger at narrow
   * widths — the new "More" tab in the bottom-nav now surfaces the
   * long-tail routes, so the hamburger is redundant on phones. */
  .top-nav .nav-links,
  .top-nav .nav-more-wrap,
  .top-nav .nav-right,
  .top-nav .nav-stats {
    display: none !important;
  }
  /* #1174: hamburger hidden at ≤768px (replaced by the More tab). */
  #hamburger {
    display: none !important;
  }
  /* Brand on the left, hamburger on the right at narrow widths. */
  .top-nav {
    justify-content: space-between;
  }

  /* Reserve space at page bottom so fixed-positioned bottom-nav does
   * not cover the last row of content. 56px tab + 8px breathing room
   * + safe-area inset. */
  body {
    padding-bottom: calc(56px + env(safe-area-inset-bottom, 0px));
  }
}

/* Tab — anchor element. Each tab is a column with icon over label, sized
 * to ≥48px tall (the Apple/Google touch-target floor confirmed by
 * issue #1060). */
.bottom-nav-tab {
  flex: 1 1 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  /* 56px is a comfortable Material/iOS bottom-bar height; it is also
   * ≥48px (a11y floor) by 8px so labels render without clipping. */
  min-height: 56px;
  padding: 6px 4px;
  color: var(--nav-text-muted);
  text-decoration: none;
  font-size: 11px;
  line-height: 1.1;
  border-top: 2px solid transparent;
  /* Reset <button> defaults — the More tab is a <button>; its native
   * background/border/font would otherwise clash with the <a> tabs. */
  border-left: 0;
  border-right: 0;
  border-bottom: 0;
  background: transparent;
  font-family: inherit;
  cursor: pointer;
  /* Touch-action: manipulation prevents the iOS double-tap zoom delay
   * on tabs. */
  touch-action: manipulation;
  transition: color 120ms ease, background-color 120ms ease, border-color 120ms ease;
}

.bottom-nav-tab:hover,
.bottom-nav-tab:focus-visible {
  color: var(--nav-text);
  outline: none;
}

.bottom-nav-tab:focus-visible {
  /* Keyboard a11y — visible focus ring inside the bar. */
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.bottom-nav-tab.active {
  color: var(--nav-text);
  background: var(--nav-active-bg);
  border-top-color: var(--accent);
}

.bottom-nav-icon {
  font-size: 20px;
  line-height: 1;
  display: block;
}

.bottom-nav-label {
  font-weight: 600;
  letter-spacing: 0.01em;
  white-space: nowrap;
}

/* Respect reduced-motion preferences — disable the color/border
 * transition. Existing app already has a reduced-motion block in
 * style.css; this is the bottom-nav-specific override. */
@media (prefers-reduced-motion: reduce) {
  .bottom-nav-tab {
    transition: none;
  }
}

/* ─── #1174: More sheet ───
 * Bottom-anchored popover that surfaces the long-tail routes (Nodes,
 * Tools, Observers, Analytics, Perf, Audio Lab). Anchored ABOVE the
 * bottom-nav (bottom: 56px + safe-area), z-index between the nav and
 * any modal layer.
 */
.bottom-nav-sheet {
  display: none;
}

@media (max-width: 768px) {
  .bottom-nav-sheet {
    /* The element uses the `hidden` attribute to be CSS-display none by
     * default; when we drop `hidden`, we want it to render as a grid. */
    position: fixed;
    left: 8px;
    right: 8px;
    /* Sit above the 56px tabs + breathing room + safe-area inset. */
    bottom: calc(56px + env(safe-area-inset-bottom, 0px) + 8px);
    z-index: 1250; /* above bottom-nav (1200), below modals if any */
    background: var(--nav-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
    padding: 8px;
    max-height: 60vh;
    overflow-y: auto;
    /* Display only when not [hidden]. */
  }
  .bottom-nav-sheet[hidden] {
    display: none !important;
  }
  .bottom-nav-sheet:not([hidden]) {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 6px;
  }
}

.bottom-nav-sheet-item {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 48px;
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--nav-text);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  background: transparent;
  border: 1px solid transparent;
  touch-action: manipulation;
  transition: background-color 120ms ease, border-color 120ms ease;
}

.bottom-nav-sheet-item:hover,
.bottom-nav-sheet-item:focus-visible {
  background: var(--nav-active-bg);
  outline: none;
}

.bottom-nav-sheet-item:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.bottom-nav-sheet-icon {
  font-size: 18px;
  line-height: 1;
}

.bottom-nav-sheet-label {
  white-space: nowrap;
}

@media (prefers-reduced-motion: reduce) {
  .bottom-nav-sheet-item {
    transition: none;
  }
}

/* ─── #1174 mesh-op review: bottom-nav mesh-alive indicator ───
 * .nav-stats (top-nav mesh-alive pulse) is hidden at ≤768. Add a thin
 * 2px top border to the bottom-nav that mirrors the brand-logo's
 * connected/disconnected state via a class toggled from app.js
 * (window.__corescopeLogo.setConnected). Cheap, peripheral-vision
 * visible, no per-tab clutter.
 *
 * Default (connected): accent-tinted border. Disconnected: red.
 * The base bottom-nav rule already declares border-top: 1px solid
 * var(--border) — we override its color with a slightly heavier
 * 2px stripe so the connectivity color is the dominant visual.
 */
@media (max-width: 768px) {
  .bottom-nav {
    border-top: 2px solid var(--accent);
    transition: border-top-color 200ms ease;
  }
  .bottom-nav.disconnected {
    border-top-color: var(--danger, #ef4444);
  }
}
@media (prefers-reduced-motion: reduce) {
  .bottom-nav {
    transition: none;
  }
}