:root {
  color-scheme: light;
  --paper: #f3f2ee;
  --surface: #fdfdfb;
  --surface-soft: #f7f6f2;
  --ink: #1d1f1c;
  --muted: #656862;
  --line: #dfddd6;
  --line-strong: #c9c6bd;
  --accent: #a23831;
  --accent-soft: #f3e4e1;
  --header: rgba(243, 242, 238, 0.88);
  --shadow: 0 1px 2px rgba(39, 35, 27, 0.04), 0 30px 80px rgba(39, 35, 27, 0.09);
  --shadow-small: 0 10px 30px rgba(39, 35, 27, 0.1);
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --theme-speed: 480ms;
  --serif: "Songti SC", "STSong", "Noto Serif CJK SC", "Source Han Serif SC", Georgia, serif;
  --sans: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --paper: #111210;
  --surface: #1a1c19;
  --surface-soft: #20221f;
  --ink: #efeee9;
  --muted: #aaada5;
  --line: #33362f;
  --line-strong: #484c43;
  --accent: #e2796d;
  --accent-soft: #3b2926;
  --header: rgba(17, 18, 16, 0.88);
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.25), 0 30px 80px rgba(0, 0, 0, 0.3);
  --shadow-small: 0 12px 34px rgba(0, 0, 0, 0.32);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --paper: #111210;
    --surface: #1a1c19;
    --surface-soft: #20221f;
    --ink: #efeee9;
    --muted: #aaada5;
    --line: #33362f;
    --line-strong: #484c43;
    --accent: #e2796d;
    --accent-soft: #3b2926;
    --header: rgba(17, 18, 16, 0.88);
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.25), 0 30px 80px rgba(0, 0, 0, 0.3);
    --shadow-small: 0 12px 34px rgba(0, 0, 0, 0.32);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 6rem;
}

body {
  margin: 0;
  min-height: 100dvh;
  overflow-x: clip;
  background:
    radial-gradient(circle at 50% -14rem, color-mix(in srgb, var(--accent-soft) 72%, transparent), transparent 34rem) no-repeat,
    var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  text-rendering: optimizeLegibility;
}

::selection {
  background: var(--accent-soft);
  color: var(--ink);
}

body,
.site-header,
.toc-panel,
.document,
.toc-button,
.theme-button,
.back-to-top,
.document-figure img {
  transition:
    background-color var(--theme-speed) var(--ease-out),
    border-color var(--theme-speed) var(--ease-out),
    color var(--theme-speed) var(--ease-out),
    box-shadow var(--theme-speed) var(--ease-out);
}

::view-transition-old(root),
::view-transition-new(root) {
  animation: none;
  mix-blend-mode: normal;
}

::view-transition-old(root) {
  z-index: 1;
}

::view-transition-new(root) {
  z-index: 2;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

a {
  color: inherit;
}

button:active,
.back-to-top:active {
  transform: translateY(1px) scale(0.98);
}

button:focus-visible,
a:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 62%, transparent);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 0.75rem;
  left: 0.75rem;
  transform: translateY(-160%);
  border-radius: 0.35rem;
  background: var(--ink);
  color: var(--paper);
  padding: 0.7rem 1rem;
  text-decoration: none;
  transition: transform 160ms ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.reading-progress {
  position: fixed;
  z-index: 60;
  inset: 0 0 auto;
  height: 3px;
  pointer-events: none;
}

.reading-progress span {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: left;
  background: var(--accent);
}

@supports (animation-timeline: scroll()) {
  .reading-progress span {
    animation: reading-progress linear both;
    animation-timeline: scroll(root block);
  }
}

.site-header {
  position: sticky;
  z-index: 30;
  top: 0;
  min-height: 4.5rem;
  border-bottom: 1px solid var(--line);
  background: var(--header);
  backdrop-filter: blur(18px) saturate(135%);
  box-shadow: 0 1px 0 color-mix(in srgb, var(--surface) 65%, transparent);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: min(100% - 4rem, 82rem);
  min-height: inherit;
  margin: 0 auto;
}

.site-mark {
  display: inline-flex;
  align-items: center;
  gap: 0.72rem;
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.12em;
  text-decoration: none;
}

.site-mark-rule {
  width: 0.2rem;
  height: 1.15rem;
  border-radius: 0.2rem;
  background: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.toc-button,
.theme-button {
  position: relative;
  min-height: 2.55rem;
  border: 1px solid var(--line);
  border-radius: 0.72rem;
  background: color-mix(in srgb, var(--surface) 86%, transparent);
  color: var(--ink);
  font: 650 0.8rem/1 var(--sans);
  cursor: pointer;
  box-shadow: inset 0 1px 0 color-mix(in srgb, var(--ink) 7%, transparent);
  transition:
    transform 180ms var(--ease-out),
    background-color 260ms var(--ease-out),
    border-color 260ms var(--ease-out),
    color 260ms var(--ease-out);
}

.toc-button:hover,
.theme-button:hover {
  border-color: color-mix(in srgb, var(--accent) 38%, var(--line));
  background: var(--accent-soft);
  color: var(--accent);
}

.toc-button {
  display: none;
  align-items: center;
  gap: 0.45rem;
  padding: 0 0.82rem;
}

.toc-button .ph {
  font-size: 1.02rem;
}

.theme-button {
  isolation: isolate;
  display: grid;
  position: relative;
  place-items: center;
  width: 2.55rem;
  padding: 0;
}

.theme-icon {
  position: absolute;
  font-size: 1.16rem;
  transition:
    opacity 320ms var(--ease-out),
    transform 420ms var(--ease-out),
    color 260ms var(--ease-out);
}

.theme-icon-light {
  color: var(--accent);
  opacity: 1;
  transform: rotate(0) scale(1);
}

.theme-icon-dark {
  color: var(--accent);
  opacity: 0;
  transform: rotate(-70deg) scale(0.55);
}

:root[data-theme="dark"] .theme-icon-light {
  opacity: 0;
  transform: rotate(70deg) scale(0.55);
}

:root[data-theme="dark"] .theme-icon-dark {
  opacity: 1;
  transform: rotate(0) scale(1);
}

.page-shell {
  display: grid;
  grid-template-columns: minmax(13rem, 16rem) minmax(0, 55rem);
  gap: clamp(3rem, 6vw, 7rem);
  width: min(100% - 4rem, 82rem);
  margin: 0 auto;
  padding: 4.5rem 0 8rem;
}

.toc-panel {
  position: sticky;
  top: 6.25rem;
  align-self: start;
  max-height: calc(100vh - 8rem);
  overflow: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--line-strong) transparent;
}

.toc-heading {
  margin-bottom: 1rem;
  color: var(--muted);
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.toc-panel ol {
  margin: 0;
  padding: 0 0 2rem;
  list-style: none;
}

.toc-panel li {
  margin: 0;
}

.toc-panel a {
  display: block;
  margin: 0.08rem 0;
  border-left: 2px solid transparent;
  border-radius: 0 0.55rem 0.55rem 0;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.45;
  padding: 0.43rem 0.75rem;
  text-decoration: none;
  transition:
    transform 240ms var(--ease-out),
    background-color 240ms var(--ease-out),
    border-color 240ms var(--ease-out),
    color 240ms var(--ease-out);
}

.toc-panel a:hover,
.toc-panel a[aria-current="location"] {
  border-left-color: var(--accent);
  color: var(--ink);
  background: color-mix(in srgb, var(--accent-soft) 68%, transparent);
  transform: translateX(0.2rem);
}

.toc-level-3 a {
  padding-left: 1.5rem;
  font-size: 0.76rem;
}

.reader-column {
  min-width: 0;
}

.document-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem 1.35rem;
  margin-bottom: 1.4rem;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.document-meta span {
  display: inline-flex;
  align-items: center;
  gap: 0.42rem;
}

.document-meta .ph {
  color: var(--accent);
  font-size: 0.95rem;
}

.document {
  position: relative;
  min-width: 0;
  overflow: hidden;
  padding: clamp(2rem, 6vw, 5.4rem) clamp(1.35rem, 6vw, 5.75rem);
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.document::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 3px;
  background: var(--accent);
}

.document h1,
.document h2,
.document h3 {
  font-family: var(--serif);
  text-wrap: balance;
  overflow-wrap: anywhere;
}

.document h1 {
  margin: 0 0 4.4rem;
  font-size: clamp(2.7rem, 8vw, 5.5rem);
  font-weight: 800;
  letter-spacing: -0.055em;
  line-height: 0.98;
}

.document h1::after {
  content: "";
  display: block;
  width: 3.4rem;
  height: 0.26rem;
  margin-top: 1.7rem;
  background: var(--accent);
}

.document h2 {
  margin: 5.2rem 0 1.7rem;
  padding-top: 1.4rem;
  border-top: 1px solid var(--line-strong);
  font-size: clamp(1.8rem, 4vw, 2.65rem);
  font-weight: 760;
  letter-spacing: -0.035em;
  line-height: 1.18;
}

.document h3 {
  margin: 3.6rem 0 1.2rem;
  color: var(--accent);
  font-size: clamp(1.25rem, 2.5vw, 1.65rem);
  font-weight: 760;
  letter-spacing: -0.015em;
  line-height: 1.35;
}

.document-paragraph {
  margin: 0.9rem 0;
  font-family: var(--serif);
  font-size: clamp(1.02rem, 1.2vw, 1.12rem);
  line-height: 1.9;
  overflow-wrap: anywhere;
}

.document-paragraph strong {
  font-weight: 800;
}

.document-paragraph u {
  text-decoration-color: color-mix(in srgb, var(--accent) 55%, transparent);
  text-decoration-thickness: 0.09em;
  text-underline-offset: 0.16em;
}

.source-red {
  color: var(--accent);
}

.document-link {
  color: var(--accent);
  font-weight: 650;
  overflow-wrap: anywhere;
  text-decoration-color: color-mix(in srgb, var(--accent) 42%, transparent);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.2em;
  transition:
    color 180ms var(--ease-out),
    text-decoration-color 180ms var(--ease-out);
}

.document-link:hover {
  color: color-mix(in srgb, var(--accent) 78%, var(--ink));
  text-decoration-color: currentColor;
}

.document-link .ph {
  display: inline-block;
  margin-left: 0.28em;
  font-size: 0.82em;
  text-decoration: none;
  vertical-align: 0.08em;
}

.chapter-label {
  margin-top: 4.2rem;
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.paragraph-space {
  height: 0.65rem;
}

.document-figure {
  margin: 2rem 0;
}

.document-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  background: var(--paper);
  box-shadow: 0 16px 42px color-mix(in srgb, var(--ink) 10%, transparent);
}

.document-footer {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 2rem;
  margin-top: 1.4rem;
  padding: 2rem 0;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.65;
}

.document-footer p {
  max-width: 38rem;
  margin: 0;
}

.document-footer a {
  flex: 0 0 auto;
  color: var(--accent);
  font-weight: 700;
  text-underline-offset: 0.2em;
}

.back-to-top {
  position: fixed;
  z-index: 25;
  right: clamp(1rem, 3vw, 2rem);
  bottom: clamp(1rem, 3vw, 2rem);
  display: grid;
  place-items: center;
  width: 2.8rem;
  height: 2.8rem;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: var(--surface);
  color: var(--ink);
  box-shadow: var(--shadow-small);
  font-size: 1.05rem;
  opacity: 0;
  pointer-events: none;
  transform: translateY(0.75rem);
  text-decoration: none;
  transition:
    opacity 260ms var(--ease-out),
    transform 260ms var(--ease-out),
    background-color var(--theme-speed) var(--ease-out),
    border-color var(--theme-speed) var(--ease-out),
    color var(--theme-speed) var(--ease-out),
    box-shadow var(--theme-speed) var(--ease-out);
}

.back-to-top[data-visible="true"] {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

@keyframes reading-progress {
  to { transform: scaleX(1); }
}

@media (prefers-reduced-motion: no-preference) {
  .site-header {
    animation: header-enter 520ms var(--ease-out) both;
  }

  .document-meta {
    animation: document-enter 620ms 40ms var(--ease-out) both;
  }

  .document {
    animation: document-enter 720ms 100ms var(--ease-out) both;
  }
}

@keyframes header-enter {
  from { opacity: 0; transform: translateY(-0.65rem); }
}

@keyframes document-enter {
  from { opacity: 0; transform: translateY(1rem); }
}

@media (max-width: 840px) {
  .header-inner {
    width: calc(100% - 2rem);
  }

  .toc-button {
    display: inline-flex;
  }

  .page-shell {
    display: block;
    width: min(100% - 1.5rem, 52rem);
    padding: 1.5rem 0 4rem;
  }

  .toc-panel {
    position: fixed;
    z-index: 40;
    inset: 4.25rem 0 auto;
    display: block;
    max-height: min(70vh, 34rem);
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--line);
    background: var(--surface);
    box-shadow: var(--shadow);
    opacity: 0;
    pointer-events: none;
    transform: translateY(-0.75rem);
    visibility: hidden;
    transition:
      opacity 260ms var(--ease-out),
      transform 260ms var(--ease-out),
      visibility 260ms,
      background-color var(--theme-speed) var(--ease-out),
      border-color var(--theme-speed) var(--ease-out),
      box-shadow var(--theme-speed) var(--ease-out);
  }

  .toc-panel[data-open="true"] {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
    visibility: visible;
  }

  body.toc-open {
    overflow: hidden;
  }

  .document h1 {
    margin-bottom: 3.5rem;
  }

  .document h2 {
    margin-top: 4.2rem;
  }

  .document-footer {
    flex-direction: column;
    gap: 1rem;
  }
}

@media (max-width: 480px) {
  .site-mark {
    letter-spacing: 0.08em;
  }

  .document {
    padding: 2.2rem 1.25rem 3rem;
    border-radius: 0.85rem;
  }

  .document h1 {
    font-size: 2.35rem;
    letter-spacing: -0.04em;
  }

  .document-paragraph {
    font-size: 1rem;
    line-height: 1.9;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }

  ::view-transition-old(root),
  ::view-transition-new(root) {
    animation-duration: 0.01ms !important;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header {
    background: var(--paper);
    backdrop-filter: none;
  }
}

@media print {
  :root {
    --paper: #ffffff;
    --surface: #ffffff;
    --ink: #000000;
    --muted: #444444;
    --line: #cccccc;
    --accent: #7f1712;
  }

  .site-header,
  .toc-panel,
  .document-meta,
  .document-footer,
  .skip-link {
    display: none !important;
  }

  .page-shell {
    display: block;
    width: 100%;
    padding: 0;
  }

  .document {
    padding: 0;
    border: 0;
    box-shadow: none;
  }
}