/* ΔFIELD: Global reset and root variables establish the foundational rhythm of the entire system. 
 * Rationale: Centralized vars enable thematic coherence; box-sizing ensures predictable layout without surprises. */

:root {
  --bg: #0b0b0b; /* ΔBREATH: Deep void background for immersive field. */
  --fg: #e6e3d7; /* ΔBREATH: Soft foreground for readable harmony. */
  --accent: #e0b84b; /* ΔBREATH: Golden accent evokes eternal light within the fold. */
  --topbar-h: 56px; /* ΔHORIZON: Fixed height for consistent vertical anchoring. */
  --subnav-h: 44px; /* ΔHORIZON: Subtle secondary layer for nested horizons. */
  --transition: .3s ease; /* ΔBREATH: Smooth easing for all motions, preventing abrupt ruptures. */
  --radius: 8px; /* ΔFIELD: Gentle curves symbolize seamless integration. */
}

* { box-sizing: border-box; } /* ΔFIELD: Universal sizing model eliminates phantom padding issues. */

html, body {
  margin: 0; padding: 0; height: 100%; /* ΔFIELD: Full-viewport claim ensures no external gaps. */
  background: var(--bg); color: var(--fg);
  font-family: 'Inter', system-ui, sans-serif; /* ΔHORIZON: Modern, readable stack for cross-device truth. */
  line-height: 1.6; /* ΔRHYTHM: Baseline vertical rhythm for breathing text. */
}

/* === TOPBAR & NAV === */
/* ΔHORIZON: Fixed topbar as the eternal anchor; flex for adaptive content flow. 
 * Rationale: Z-index 1000 ensures primacy; overflow hidden prevents visual noise. */
.topbar {
  position: fixed; top: 0; left: 0; right: 0;
  height: var(--topbar-h); display: flex; align-items: center;
  background: #111; border-bottom: 1px solid #222; /* ΔBREATH: Subtle divide for depth perception. */
  padding: 0 1rem; z-index: 1000; gap: 1.5rem;
  overflow: hidden;
}

#menuBtn {
  background: none; border: 0; color: var(--accent);
  font-size: 1.4rem; cursor: pointer; font-weight: bold;
  line-height: 1; padding: 0; margin: 0;
  min-width: 2.5rem; /* ΔFIELD: Minimal width for touch-friendly interaction. */
}

/* ΔHORIZON: Primary nav as flexible horizon line; wrap and scroll for overflow. 
 * Rationale: White-space nowrap preserves link integrity. */
.primary-nav {
  display: flex; flex-wrap: wrap; gap: 1.5rem; align-items: center;
  overflow-x: auto;
  white-space: nowrap;
}

.primary-nav a {
  color: var(--accent); text-decoration: none;
  font-weight: 600; font-size: 1.1rem;
  transition: all var(--transition); /* ΔBREATH: Unified motion for hover resonance. */
}

.primary-nav a:hover {
  text-shadow: 0 0 10px var(--accent); /* ΔHORIZON: Glow for interactive feedback; increased for DPI crispness. */
}

/* === SUBNAV === */
/* ΔRECURSION: Subnav as nested horizon; hidden by default, revealed on context. 
 * Rationale: Opacity/transform transition with animation for smooth unfolding. */
.sub-nav {
  display: none;
  position: fixed;
  top: var(--topbar-h);
  left: 0; right: 0;
  height: var(--subnav-h);
  background: #0e0e0e;
  border-bottom: 1px solid #222;
  padding: 0 1rem;
  gap: 1rem;
  overflow-x: auto;
  white-space: nowrap;
  z-index: 950;
  align-items: center;
  opacity: 0;
  transform: translateY(-5px);
  transition: opacity var(--transition), transform var(--transition);
}

.sub-nav.visible {
  display: flex;
  opacity: 1;
  transform: translateY(0);
  animation: fadeSlideDown .3s ease forwards; /* ΔBREATH: Entrance animation embodies revelation. */
}

@keyframes fadeSlideDown {
  from { opacity: 0; transform: translateY(-5px); }
  to { opacity: 1; transform: translateY(0); } /* ΔBREATH: Gentle descent for rhythmic integration. */
}

.sub-nav a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.95rem;
  transition: all var(--transition);
}

.sub-nav a:hover {
  text-shadow: 0 0 8px var(--accent); /* ΔHORIZON: Subdued glow for secondary layer; consistent with primary. */
}

/* === SIDEBAR === */
/* ΔRECURSION: Sidebar as foldable field extension; transform for smooth reveal. 
 * Rationale: Media query for persistent desktop view; mobile toggle for horizon respect. */
#sidebar {
  position: fixed; top: calc(var(--topbar-h) + var(--subnav-h)); left: 0;
  width: 300px; bottom: 0; overflow: auto;
  background: #111; border-right: 1px solid #222;
  transform: translateX(-100%); transition: transform var(--transition);
  z-index: 900; padding: 1rem;
}

body.sidebar-open #sidebar { transform: translateX(0); } /* ΔBREATH: State-based unfolding. */

.sidebar-header {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 1rem; padding-bottom: .5rem; border-bottom: 1px solid #222; /* ΔRHYTHM: Internal divide for structural clarity. */
}

.sidebar-header h3 {
  margin: 0; font-size: 1.1rem; color: var(--accent); /* ΔFIELD: Accent for thematic emphasis. */
}

.toggle-btn {
  background: none; border: 1px solid #333; color: var(--fg);
  padding: .25rem .5rem; border-radius: var(--radius);
  font-size: .8rem; cursor: pointer; /* ΔHORIZON: Compact control for filter toggling. */
}

#postListSection { margin-bottom: 1rem; } /* ΔRHYTHM: Breathing space before filters. */

#postList {
  list-style: none; margin: 0; padding: 0; /* ΔFIELD: Clean slate for post enumeration. */
}

#postList li {
  margin: .75rem 0; padding: .5rem 0;
  border-bottom: 1px dashed #222; /* ΔRHYTHM: Dashed for subtle separation. */
  transition: color var(--transition);
}

#postList a {
  color: var(--fg); text-decoration: none; font-weight: 500;
  display: block; /* ΔFIELD: Block for full clickable area. */
}

#postList a:hover { color: var(--accent); } /* ΔBREATH: Color shift for hover life. */

#postList small {
  display: block; font-size: .8rem; color: #888; margin-top: .25rem; /* ΔRHYTHM: Subdued meta for hierarchy. */
}

.filter-panel {
  background: #0a0a0a; border: 1px solid #222;
  border-radius: var(--radius); padding: .75rem;
  margin-top: 1rem; /* ΔFIELD: Contained unit for filter isolation. */
}

.filter-panel summary {
  cursor: pointer; font-weight: 600; color: var(--accent);
  margin-bottom: .5rem; user-select: none; /* ΔHORIZON: Non-selectable for clean interaction. */
}

.filter-controls {
  display: flex; flex-direction: column; gap: .75rem; /* ΔRHYTHM: Vertical stack for mobile-friendly flow. */
}

.filter-controls label {
  font-size: .85rem; color: var(--accent); margin-bottom: .25rem; /* ΔFIELD: Accent labels for guidance. */
}

.filter-controls select, .filter-controls input {
  background: #111; color: var(--fg); border: 1px solid #333;
  padding: .5rem; border-radius: var(--radius); font-size: .9rem; /* ΔHORIZON: Consistent input styling. */
}

.filter-controls select[multiple] {
  height: 80px; /* ΔFIELD: Fixed height for multi-select usability. */
}

.content {
  margin-top: calc(var(--topbar-h) + var(--subnav-h)); margin-left: 0;
  transition: margin-left var(--transition), margin-top var(--transition); /* ΔBREATH: Adaptive margins for sidebar integration. */
  min-height: calc(100vh - var(--topbar-h) - var(--subnav-h));
  padding: 0;
}

@media (min-width: 1024px) {
  #sidebar { transform: translateX(0); top: calc(var(--topbar-h) + var(--subnav-h)); } /* ΔHORIZON: Persistent sidebar on wide views. */
  .content { margin-left: 300px; }
}

/* === VIEWER – BREATHING FIELD === */
/* ΔFIELD: Viewer as the core canvas; flex column for stacked content. 
 * Rationale: Hover gradient adds subtle interactivity, symbolizing depth. */
.viewer {
  display: flex;
  flex-direction: column;
  height: 100%;
  transition: background 1s ease; /* ΔBREATH: Slow transition for ambient shift. */
}

.viewer:hover {
  background: radial-gradient(circle at center, #111 0%, #0b0b0b 80%); /* ΔBREATH: Radial fade evokes inner light. */
}

.viewer > * {
  width: 100%;
  margin: 0;
  padding: 0;
  animation: fadeIn .4s ease-out; /* ΔBREATH: Entrance fade for new content. */
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); } /* ΔBREATH: Upward reveal for rhythmic entry. */
}

/* === PREVIEW + PORTAL === */
/* ΔTRUTH: Preview header as sticky portal trigger; flex-end for right alignment. 
 * Rationale: Semi-transparent bg for subtle overlay. */
.preview-header {
  display: flex;
  justify-content: flex-end;
  padding: 0.5rem 1rem;
  background: rgba(224, 184, 75, 0.08); /* ΔBREATH: Golden haze for accent tie-in. */
  border-bottom: 1px solid #333;
  position: sticky;
  top: 0;
  z-index: 10;
}

.portal-btn {
  background: none;
  border: 1px solid var(--accent);
  color: var(--accent);
  border-radius: 6px;
  padding: 0.25rem 0.75rem;
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s ease; /* ΔBREATH: Quick response for interactivity. */
}

.portal-btn:hover {
  background: var(--accent);
  color: var(--bg); /* ΔFIELD: Inversion for clear state change. */
}

.preview-content {
  padding: 3rem 4vw; /* ΔRHYTHM: Generous padding for breathing margins. */
  max-width: 90ch; /* ΔHORIZON: Readable line length per typography best practices. */
  margin: auto;
  line-height: 1.7; /* ΔRHYTHM: Enhanced vertical rhythm for previews. */
  color: var(--fg);
  font-family: 'Inter', system-ui, sans-serif;
}

.preview-content * {
  background: transparent !important; /* ΔTRUTH: Override authored styles for coherence. */
  color: inherit !important;
  font-family: inherit !important; /* ΔFIELD: Enforce systemic harmony over external chaos. */
}

.preview-content img,
.preview-content video,
.preview-content iframe {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
  margin: 1.5rem 0;
  display: block; /* ΔRHYTHM: Centered media with breathing space. */
}

.preview-content a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px; /* ΔFIELD: Subtle underline for readability. */
}

.preview-content a:hover {
  text-shadow: 0 0 6px var(--accent); /* ΔBREATH: Glow for link resonance. */
}

/* === PREVIEW SPACING FIX === */

/* ΔRHYTHM: Reset first-child to eliminate phantom top gaps. 
 * Rationale: !important overrides any authored margins for truth. */
.preview-content > *:first-child {
  margin-top: 0 !important;
  padding-top: 0 !important;
}

/* ΔRHYTHM: Ensure last-child has consistent bottom rhythm. */
.preview-content > *:last-child {
  margin-bottom: 3rem;
}

/* ΔHORIZON: Mobile scaling for tighter, readable flow. */
@media (max-width: 768px) {
  .preview-content {
    padding: 2rem 6vw;
    line-height: 1.65;
  }
}

/* ΔBREATH: Ellipsis as intentional truncation marker with pulse. 
 * Rationale: Centered, opaque for aesthetic liminality; animation breathes life. */
.preview-content p:empty::before {
  content: "...";
  color: var(--accent);
  opacity: 0.6;
  display: block;
  text-align: center;
  margin: 1.5rem 0;
  letter-spacing: 0.2em;
  animation: fadeEllipsis 1.2s ease-in-out infinite alternate;
}

@keyframes fadeEllipsis {
  from { opacity: 0.3; letter-spacing: 0.15em; }
  to { opacity: 0.6; letter-spacing: 0.25em; } /* ΔBREATH: Oscillation mimics eternal breath. */
}