:root {
  --bg:             #0a0a0d;
  --text:           #e8e0d0;
  --text-dim:       #a09890;
  --text-muted:     #605860;
  --lavender:       #c8b8d8;
  --teal:           #88c0c0;
  --accent-bg:      #18181e;
  --border:         #282830;
  --swatch-boot:    #18181e;
  --swatch-super:   #4a3a5a;
  --swatch-group:   #3a5a5a;
  --swatch-data:    #6a5a3a;
  --swatch-btrfs-boot:  #18181e;
  --swatch-btrfs-super: #5a3a4a;
  --swatch-btrfs-chunk: #3a4a5a;
  --swatch-btrfs-tree:  #5a5a3a;

  --font: 'IBM Plex Mono', 'JetBrains Mono', 'Berkeley Mono', 'Courier New', monospace;
  --fw-light: 300;
  --fw-regular: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 15px; }
@media (max-width: 700px) { html { font-size: 13px; } }

body {
  font-family: var(--font);
  font-weight: var(--fw-regular);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--teal); }
a:hover { color: var(--lavender); text-decoration: underline; }

::selection { background: #3a3450; color: var(--text); }

/* ── Scrollbar ────────────────────────────────────────────────────── */

/* Chromium */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: #101014;
}

::-webkit-scrollbar-thumb {
  background: #3a3836;
  border-radius: 3px;
  transition: background 0.2s ease;
}

::-webkit-scrollbar-thumb:hover {
  background: #4e4c48;
}

::-webkit-scrollbar-thumb:active {
  background: #5e5c58;
}

::-webkit-scrollbar-corner {
  background: #101014;
}

/* Firefox */
* {
  scrollbar-width: thin;
  scrollbar-color: #3a3836 #101014;
}

.page {
  max-width: 840px;
  margin: 0 auto;
  padding: 2.5rem 2rem 5rem;
}
@media (max-width: 700px) {
  .page { padding: 1.5rem 1rem 3rem; }
}

/* ── MASTHEAD ─────────────────────────────────────────────────────── */

.masthead { margin-bottom: 2.5rem; }
.masthead-inner { margin-bottom: 1.5rem; text-align: center; }

.project-name {
  font-size: 5.5rem;
  font-weight: var(--fw-semibold);
  letter-spacing: 0.08em;
  color: var(--text);
  margin-bottom: 0.75rem;
  line-height: 0.95;
}
@media (max-width: 700px) {
  .project-name { font-size: 3rem; letter-spacing: 0.05em; }
}

.project-sub {
  font-size: 1rem;
  font-weight: var(--fw-regular);
  color: var(--text-dim);
  margin-bottom: 1rem;
}

.project-meta-line {
  font-size: 0.8rem;
  color: var(--text-muted);
}
.project-meta-line a { color: var(--text-dim); }

.meta-dot {
  color: var(--text-muted);
  margin: 0 0.6em;
}

.btn-download {
  display: inline-block;
  margin-top: 1.2rem;
  border: 1px solid var(--lavender);
  color: var(--lavender);
  padding: 0.5rem 1.2rem;
  font-size: 0.8rem;
  font-family: var(--font);
  font-weight: var(--fw-medium);
  letter-spacing: 0.05em;
  text-decoration: none;
  transition: background 0.25s, color 0.25s;
}

.btn-download:hover {
  background: var(--lavender);
  color: var(--bg);
  text-decoration: none;
}

/* ── SUPERBLOCK ────────────────────────────────────────────────────── */

.superblock-card {
  font-size: 0.82rem;
  color: var(--text-dim);
  background: var(--accent-bg);
  padding: 0.8rem 1rem;
  margin-bottom: 4rem;
}
@media (max-width: 700px) {
  .superblock-card { padding: 0.6rem 0.8rem; }
}

.sb-header {
  color: var(--text-muted);
  font-weight: var(--fw-medium);
  font-size: 0.68rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.sb-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.4rem 1.5rem;
}
@media (max-width: 480px) {
  .sb-grid {
    grid-template-columns: 1fr;
    gap: 0.4rem 0;
  }
}

.sb-item { display: flex; gap: 0.3em; }
.sb-wide { grid-column: 1 / -1; }

.sb-label { color: var(--text-muted); opacity: 0.6; }
.sb-label::after { content: "="; color: var(--text-muted); opacity: 0.6; margin: 0 0.25em; }
.sb-value { color: var(--text); }

.sb-features { display: inline; }
.sb-chip { color: var(--lavender); }
.sb-chip + .sb-chip::before { content: ", "; color: var(--text-muted); }

/* ── LAYOUT CARD ───────────────────────────────────────────────────── */

.layout-card {
  margin-bottom: 2.5rem;
  font-size: 0.8rem;
  color: var(--text-dim);
}

.layout-title {
  font-size: 0.72rem;
  font-weight: var(--fw-medium);
  color: var(--text-dim);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
}

.layout-bar {
  display: flex;
  height: 2.4rem;
  margin-bottom: 0.5rem;
}

.layout-seg { height: 100%; }
.seg-boot  { width: 15%; background: var(--swatch-boot); }
.seg-super { width: 10%; background: var(--swatch-super); }
.seg-group { width: 15%; background: var(--swatch-group); }
.seg-data  { width: 60%; background: var(--swatch-data); }
.seg-btrfs-boot  { width: 10%; background: var(--swatch-btrfs-boot); }
.seg-btrfs-super { width: 5%;  background: var(--swatch-btrfs-super); }
.seg-btrfs-chunk { width: 25%; background: var(--swatch-btrfs-chunk); }
.seg-btrfs-tree  { width: 60%; background: var(--swatch-btrfs-tree); }

.layout-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 1.2rem;
  font-size: 0.72rem;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
}

.legend-swatch {
  display: inline-block;
  width: 0.55rem;
  height: 0.55rem;
  margin-right: 0.3em;
  vertical-align: middle;
}
.swatch-boot  { background: var(--swatch-boot); }
.swatch-super { background: var(--swatch-super); }
.swatch-group { background: var(--swatch-group); }
.swatch-data  { background: var(--swatch-data); }
.swatch-btrfs-boot  { background: var(--swatch-btrfs-boot); }
.swatch-btrfs-super { background: var(--swatch-btrfs-super); }
.swatch-btrfs-chunk { background: var(--swatch-btrfs-chunk); }
.swatch-btrfs-tree  { background: var(--swatch-btrfs-tree); }


.layout-addr {
  display: flex;
  font-size: 0.68rem;
  color: var(--text-muted);
  gap: 0;
}

.layout-addr span { display: block; }
.layout-addr span:nth-child(1) { width: 15%; }
.layout-addr span:nth-child(2) { width: 10%; }
.layout-addr span:nth-child(3) { width: 15%; }
.layout-addr span:nth-child(4) { width: 60%; }

/* ── SPLIT LAYOUT ──────────────────────────────────────────────────── */

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-bottom: 3rem;
  align-items: start;
}

.split > .chapter {
  margin-bottom: 0;
}
@media (max-width: 800px) {
  .split { grid-template-columns: 1fr; }
}

/* ── CHAPTERS ──────────────────────────────────────────────────────── */

.chapter { margin-bottom: 4rem; }

.ch-meta {
  font-size: 0.65rem;
  font-weight: var(--fw-semibold);
  color: var(--text-muted);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.4rem;
}
.ch-meta-dia { color: var(--lavender); margin-right: 0.5em; }

.ch-title {
  font-size: 2rem;
  font-weight: var(--fw-medium);
  color: var(--text);
  letter-spacing: -0.01em;
  margin-bottom: 1.5rem;
  line-height: 1.1;
}
@media (max-width: 700px) {
  .ch-title { font-size: 1.4rem; }
}

.ch-text {
  font-size: 0.95rem;
  color: var(--text-dim);
  margin-bottom: 1rem;
  max-width: 60ch;
  line-height: 1.8;
}

.ch-note {
  margin-top: 1.5rem;
  padding-left: 1rem;
  font-size: 0.85rem;
  color: var(--text-dim);
  line-height: 1.7;
  max-width: 58ch;
}

.note-indicator { color: var(--lavender); margin-right: 0.5em; font-size: 0.55rem; }

/* ── ARCHITECTURE DIAGRAM ──────────────────────────────────────────── */

.arch {
  text-align: center;
}

.arch-layer {
  padding: 0.6rem 0;
}

.arch-name {
  font-size: 1rem;
  font-weight: var(--fw-medium);
  color: var(--text);
  letter-spacing: 0.03em;
  margin-bottom: 0.3rem;
}

.arch-info {
  font-size: 0.72rem;
  color: var(--text-dim);
  line-height: 1.6;
}

.arch-sep {
  color: var(--text-muted);
  margin: 0 0.45em;
}

.arch-arrow {
  width: 2px;
  height: 2.2rem;
  margin: 0 auto 0.2rem;
  background: var(--text-muted);
  opacity: 0.6;
}

.arch-mid {
  padding: 0.8rem 0;
}

.arch-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem 3rem;
  margin-top: 1rem;
  text-align: left;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

@media (max-width: 500px) {
  .arch-grid { grid-template-columns: 1fr; }
}

.arch-comp-name {
  font-size: 0.78rem;
  font-weight: var(--fw-medium);
  color: var(--lavender);
  margin-bottom: 0.15rem;
}

.arch-comp-info {
  font-size: 0.7rem;
  color: var(--text-dim);
  line-height: 1.5;
}

/* ── CAPABILITIES ──────────────────────────────────────────────────── */

.cap-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}
@media (max-width: 700px) {
  .cap-grid { grid-template-columns: 1fr; }
}

.cap-group-title {
  font-size: 0.8rem;
  font-weight: var(--fw-semibold);
  color: var(--text-muted);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
}

.cap-list {
  list-style: none;
  font-size: 0.95rem;
  color: var(--text-dim);
}
.cap-list li {
  padding: 0.15rem 0 0.15rem 1em;
  position: relative;
}
.cap-list li::before {
  content: "\25C6";
  position: absolute;
  left: 0;
  color: var(--text-muted);
  font-size: 0.45rem;
  top: 0.4em;
}

/* ── TREE ──────────────────────────────────────────────────────────── */

.tree {
  font-size: 0.85rem;
  line-height: 1.7;
  overflow-x: auto;
  color: var(--text-dim);
}
.t-f { color: var(--text); }
.t-d { color: var(--lavender); }

.fig-cap {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.3rem;
  padding-left: 1rem;
}

/* ── USAGE ──────────────────────────────────────────────────────────── */

.cmd {
  margin-bottom: 1.8rem;
  max-width: 46rem;
}

.cmd-tag {
  display: inline-block;
  font-size: 0.6rem;
  font-weight: var(--fw-medium);
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: lowercase;
  margin-bottom: 0.35rem;
}

.cmd-block {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--accent-bg);
  border: 1px solid var(--border);
  padding: 0.65rem 1rem;
}

.cmd-code {
  font-size: 0.9rem;
  color: var(--text);
  font-family: var(--font);
  word-break: break-all;
}

.cmd-copy {
  flex-shrink: 0;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-family: var(--font);
  font-size: 0.72rem;
  opacity: 0;
  transition: opacity 0.2s, color 0.2s;
  padding: 0.2rem 0.15rem 0.2rem 0.5rem;
  line-height: 1;
}

.cmd-block:hover .cmd-copy {
  opacity: 1;
}

.cmd-copy:hover {
  color: var(--lavender);
}

.cmd-copy.copied {
  opacity: 1;
  color: var(--teal);
}

.cmd-desc {
  font-size: 0.82rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
  line-height: 1.6;
  padding-left: 0.5rem;
}

.cmd-desc code {
  font-size: inherit;
  color: var(--teal);
}

.cmd-example {
  margin-top: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding-left: 0.5rem;
}

.cmd-example-label {
  font-size: 0.55rem;
  font-weight: var(--fw-medium);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  flex-shrink: 0;
}

.cmd-example code {
  font-size: 0.75rem;
  color: var(--text-dim);
  background: var(--accent-bg);
  border: 1px solid var(--border);
  padding: 0.25rem 0.6rem;
  font-family: var(--font);
}

.cmd-note { margin-top: 1.5rem; }

/* ── BOUNDARIES ────────────────────────────────────────────────────── */

.bound-wrap {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: 2rem;
}
@media (max-width: 800px) {
  .bound-wrap { grid-template-columns: 1fr; }
}

.bound-tbl {
  width: 100%;
  font-size: 0.85rem;
}

.bound-tbl th {
  text-align: left;
  font-weight: var(--fw-semibold);
  color: var(--text-muted);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-size: 0.68rem;
  padding: 0.3rem 0;
}

.bound-tbl td {
  padding: 0.3rem 0.6rem 0.3rem 0;
  color: var(--text-dim);
  vertical-align: top;
  line-height: 1.5;
}

.b-term { color: var(--lavender); font-weight: var(--fw-medium); white-space: nowrap; }

.bound-notes {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.b-note-ref {
  display: block;
  font-weight: var(--fw-semibold);
  font-size: 0.68rem;
  color: var(--teal);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.1rem;
}

.b-note-body {
  font-size: 0.8rem;
  color: var(--text-dim);
  line-height: 1.6;
}

/* ── ROADMAP ───────────────────────────────────────────────────────── */

.roadmap-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.roadmap-phase {
  border: 1px solid var(--border);
  background: var(--bg-card);
  padding: 1.2rem;
  border-radius: 4px;
  position: relative;
  transition: border-color 0.2s;
}

.roadmap-completed {
  border-color: var(--teal);
}

.roadmap-active {
  border-color: var(--lavender);
}

.phase-hdr {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  margin-bottom: 0.8rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.6rem;
}

.phase-badge {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: var(--fw-semibold);
  width: max-content;
  padding: 0.15rem 0.4rem;
  border-radius: 2px;
}

.roadmap-completed .phase-badge {
  background: rgba(45, 179, 147, 0.1);
  color: var(--teal);
}

.roadmap-active .phase-badge {
  background: rgba(180, 168, 252, 0.1);
  color: var(--lavender);
}

.phase-title {
  font-size: 0.95rem;
  font-weight: var(--fw-semibold);
  color: var(--text-normal);
}

.phase-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.phase-list li {
  font-size: 0.82rem;
  color: var(--text-dim);
  line-height: 1.4;
  position: relative;
  padding-left: 0.8rem;
}

.phase-list li::before {
  content: "◆";
  position: absolute;
  left: 0;
  font-size: 0.5rem;
  top: 0.4rem;
}

.roadmap-completed .phase-list li::before {
  color: var(--teal);
}

.roadmap-active .phase-list li::before {
  color: var(--lavender);
}

/* ── COLOPHON ──────────────────────────────────────────────────────── */

.colophon { margin-top: 4rem; }

.colophon-inner {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.colophon-line {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.colophon-l {
  color: var(--text-muted);
  text-transform: uppercase;
  font-size: 0.68rem;
  letter-spacing: 0.1em;
}

.colophon-dot { color: var(--text-muted); margin: 0 0.4em; }

/* ── PRINT ──────────────────────────────────────────────────────────── */

@media print {
  body { background: #fff; color: #000; }
  a { color: #000 !important; }
  .superblock-card,
  .topo-block { background: #f0f0f0 !important; }
}

/* ── MATRIX COMPARISON TABLE ────────────────────────────────────────── */

.matrix-table-wrapper {
  overflow-x: auto;
  border: 1px solid var(--border);
  background: var(--accent-bg);
  margin-top: 0.8rem;
  border-radius: 4px;
}

.matrix-tbl {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
  color: var(--text-dim);
}

.matrix-tbl th {
  background: rgba(40, 40, 48, 0.3);
  font-weight: var(--fw-semibold);
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 0.68rem;
  padding: 0.8rem 1rem;
  border-bottom: 1px solid var(--border);
  text-align: left;
}

.matrix-tbl td {
  padding: 0.8rem 1rem;
  border-bottom: 1px solid rgba(40, 40, 48, 0.5);
  vertical-align: middle;
}

.matrix-tbl tr:last-child td {
  border-bottom: none;
}

.matrix-tbl tr:hover {
  background: rgba(200, 184, 216, 0.02);
}

.text-center { text-align: center; }

.status-yes {
  color: var(--teal);
  font-weight: var(--fw-medium);
}

.status-no {
  color: var(--text-muted);
}

.status-warning {
  color: var(--lavender);
  font-size: 0.72rem;
  display: block;
}

/* ── MOBILE RESPONSIVE OVERRIDES ─────────────────────────────────────── */

@media (max-width: 700px) {
  /* Prevent horizontal overflow completely */
  html, body {
    overflow-x: hidden;
    width: 100%;
  }

  /* Masthead download button spacing and full-width */
  .masthead {
    margin-bottom: 2rem;
  }
  .btn-download {
    display: block;
    width: 100%;
    text-align: center;
    padding: 0.7rem 1.2rem;
    font-size: 0.85rem;
    margin-top: 1.5rem;
  }
  /* Center and stack masthead metadata */
  .project-meta-line {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.4rem;
    text-align: center;
  }
  .project-meta-line .meta-dot {
    display: none;
  }
  /* Scale down spaced project title on small screens to prevent overflow */
  .project-name {
    font-size: 2.2rem;
    letter-spacing: 0.04em;
  }
}

@media (max-width: 600px) {
  /* Page padding */
  .page {
    padding: 1.5rem 1rem 3rem;
  }

  /* Volume layouts padding, alignment, and centering */
  .layout-card {
    padding: 0; /* Remove double padding to align layout bars with body copy margins */
  }
  .layout-title {
    text-align: center;
  }
  .layout-legend {
    justify-content: center;
  }
  .layout-addr {
    font-size: 0.58rem;
    justify-content: center;
  }
  .layout-addr span {
    text-align: center;
  }

  /* Comparison Matrix table optimizations */
  .matrix-tbl th, .matrix-tbl td {
    padding: 0.5rem 0.4rem;
    font-size: 0.72rem;
  }
  .matrix-tbl th:nth-child(4), .matrix-tbl td:nth-child(4) {
    display: none; /* Hide details column on mobile to keep the chart perfectly clean and fitting */
  }

  /* Collapsed architecture components indicator tree on mobile */
  .arch-comp {
    border-left: 2px solid var(--border);
    padding-left: 0.8rem;
    margin-bottom: 0.5rem;
  }

  /* Source structure tree code container adjustments */
  .tree {
    font-size: 0.72rem;
    padding: 0.5rem;
    background: rgba(24, 24, 30, 0.2);
    border: 1px solid rgba(40, 40, 48, 0.3);
  }

  /* Stack Known Boundaries table into readable vertical cards on mobile */
  .bound-tbl, .bound-tbl thead, .bound-tbl tbody, .bound-tbl th, .bound-tbl td, .bound-tbl tr {
    display: block;
  }
  .bound-tbl thead {
    display: none;
  }
  .bound-tbl tr {
    border-bottom: 1px solid var(--border);
    padding: 0.8rem 0;
  }
  .bound-tbl tr:last-child {
    border-bottom: none;
  }
  .bound-tbl td {
    padding: 0.15rem 0;
    font-size: 0.78rem;
  }
  .bound-tbl td:nth-child(1) {
    font-weight: var(--fw-semibold);
    color: var(--teal);
    font-size: 0.82rem;
  }
  .bound-tbl td:nth-child(2)::before {
    content: "Impact: ";
    color: var(--text-muted);
    font-size: 0.7rem;
    text-transform: uppercase;
    font-weight: var(--fw-medium);
  }
  .bound-tbl td:nth-child(3)::before {
    content: "Rationale: ";
    color: var(--text-muted);
    font-size: 0.7rem;
    text-transform: uppercase;
    font-weight: var(--fw-medium);
  }

  /* Notes text alignment */
  .ch-note {
    padding-left: 0.8rem;
    margin-top: 1rem;
    font-size: 0.8rem;
  }
}