/* ============================================================
   Epistle — CSS 主样式
   结构：变量 → 主题 → 布局 → 组件 → 工具 → 响应式
   ============================================================ */

/* ── 变量：默认主题（白纸蓝墨） ── */
:root {
  --color-desk:    #E8E4DF;
  --color-paper:   #FFFFFF;
  --color-paper-rgb: 255, 255, 255;
  --color-ink:     #1C2333;
  --color-meta:    #718096;
  --color-accent:  #2C5282;
  --color-fold:    rgba(28, 35, 51, 0.08);
  --shadow-paper:  0 2px 20px rgba(0, 0, 0, 0.08);

  --font-body:     "Iowan Old Style", "Palatino Linotype", "Book Antiqua", "Noto Serif", "Songti SC", "STSong", "Source Han Serif SC", "Noto Serif CJK SC", "SimSun", "宋体", serif;
  --font-title:     "Kaiti SC", "Kaiti TC", "STKaiti", "KaiTi", "楷体", serif;
  --font-signature: "Kaiti SC", "Kaiti TC", "STKaiti", "KaiTi", "楷体", serif;

  --width-content: 44rem;
  --width-sidebar: 14rem;
  --size-body:     18px;
  --line-height:   1.75;
  --spacing-para:  1.5rem;

  --dappled-enabled: 1;
  --paper-alpha: 0.9;
}

/* ── 主题覆盖 ── */
[data-style="warm"] {
  --color-desk:    #D6C9B6;
  --color-paper:   #FEF9F0;
  --color-paper-rgb: 254, 249, 240;
  --color-ink:     #2C1F0E;
  --color-meta:    #8B7355;
  --color-accent:  #7B4F2E;
  --color-fold:    rgba(44, 31, 14, 0.08);

  --paper-alpha: 0.88;
}

[data-style="sky"] {
  --color-desk:    #C9DFF0;
  --color-paper:   #EBF4FB;
  --color-paper-rgb: 235, 244, 251;
  --color-ink:     #1A3A52;
  --color-meta:    #5A8FA8;
  --color-accent:  #1A6FA8;
  --color-fold:    rgba(26, 58, 82, 0.1);

  --paper-alpha: 0.9;
}

[data-style="night"] {
  --color-desk:    #0D1117;
  --color-paper:   #161B22;
  --color-paper-rgb: 22, 27, 34;
  --color-ink:     #CDD9E5;
  --color-meta:    #768390;
  --color-accent:  #79C0FF;
  --color-fold:    rgba(205, 217, 229, 0.1);
  --shadow-paper:  0 2px 20px rgba(0, 0, 0, 0.4);

  --paper-alpha: 0.86;
}

[data-style="spring"] {
  --color-desk:    #DDE8DC;
  --color-paper:   #F4FAF4;
  --color-paper-rgb: 244, 250, 244;
  --color-ink:     #1F3324;
  --color-meta:    #5A7A64;
  --color-accent:  #2D6A4F;
  --color-fold:    rgba(31, 51, 36, 0.08);

  --paper-alpha: 0.9;
}

/* ── 基础重置 ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: var(--size-body); scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background-color: var(--color-desk);
  color: var(--color-ink);
  line-height: var(--line-height);
  min-height: 100vh;
  overflow-x: hidden;
}

body[data-dappled="off"] {
  --dappled-enabled: 0;
}

/* ── 布局 ── */
.desk {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.layout,
.site-header,
.site-footer {
  position: relative;
  z-index: 1;
}

.layout {
  display: flex;
  flex: 1;
  max-width: calc(var(--width-content) + 4rem);
  margin: 0 auto;
  width: 100%;
  padding: 0 1.5rem;
}

/* ── 信纸（主内容） ── */
.paper {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  background: linear-gradient(
    180deg,
    rgba(var(--color-paper-rgb), calc(var(--paper-alpha) + 0.05)) 0%,
    rgba(var(--color-paper-rgb), var(--paper-alpha)) 38%,
    rgba(var(--color-paper-rgb), calc(var(--paper-alpha) - 0.04)) 100%
  );
  box-shadow: var(--shadow-paper);
  padding: 3rem 3.5rem 4rem;
  border-right: 1px solid var(--color-fold);
  min-height: calc(100vh - 8rem);
  backdrop-filter: blur(14px) saturate(118%) brightness(1.02);
  -webkit-backdrop-filter: blur(14px) saturate(118%) brightness(1.02);
}

.paper > * {
  position: relative;
  z-index: 1;
}

@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .paper {
    background: linear-gradient(
      180deg,
      rgba(var(--color-paper-rgb), 0.92) 0%,
      rgba(var(--color-paper-rgb), 0.9) 100%
    );
  }
}

/* ── 页眉 ── */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 1.5rem;
  max-width: calc(var(--width-content) + var(--width-sidebar) + 4rem);
  margin: 0 auto;
  width: 100%;
}

.site-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-ink);
  text-decoration: none;
  letter-spacing: 0.05em;
}

/* ── 信笺索引标签 ── */
.index-tab {
  position: fixed;
  right: -2px;
  top: 5rem;
  z-index: 200;

  /* 牛皮纸标签页 */
  background: rgba(var(--color-paper-rgb), 0.7);
  color: var(--color-meta);
  border: 1px solid var(--color-fold);
  border-right: none;
  border-radius: 4px 0 0 4px;
  padding: 0.8rem 0.35rem;

  /* 竖排文字 */
  writing-mode: vertical-rl;
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.25em;

  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  -webkit-appearance: none;
  appearance: none;
  box-shadow: -1px 1px 4px rgba(0, 0, 0, 0.06);
  /* 位移与侧栏同通道（transform）同时长，保证同步滑动 */
  transition: transform 0.35s ease, background 0.2s ease, box-shadow 0.2s ease, color 0.2s ease, padding 0.2s ease;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.index-tab:focus,
.index-tab:focus-visible { outline: none; }

.index-tab:hover {
  background: rgba(var(--color-paper-rgb), 0.88);
  padding-right: 0.5rem;
  box-shadow: -2px 2px 8px rgba(0, 0, 0, 0.1);
  color: var(--color-ink);
}

.index-tab.is-active {
  background: rgba(var(--color-paper-rgb), 0.92);
  color: var(--color-ink);
  /* 跟随侧边栏移动：与侧栏相同的位移距离 */
  transform: translateX(calc(-1 * min(320px, 85vw) - 2px));
}

/* ── 信件正文结构 ── */
.letter { max-width: var(--width-content); }

.letter-header {
  margin-bottom: 1.5rem;
  text-align: center;
}

.letter .letter-title {
  font-family: var(--font-title);
  font-size: 1.8rem;
  font-weight: 400;
  line-height: 1.4;
}

.letter-body h1,
.letter-body h2,
.letter-body h3,
.letter-body h4,
.letter-body h5,
.letter-body h6 {
  font-family: "Kaiti SC", "Kaiti TC", "STKaiti", "KaiTi", "楷体", "AR PL UKai CN", serif;
  font-weight: 400;
}

.letter-date {
  font-size: 0.85rem;
  color: var(--color-meta);
  display: block;
}

.letter-date--footer {
  display: block;
  margin-top: 1rem;
  font-size: 0.875rem;
}

.letter-body p + p { margin-top: var(--spacing-para); }

/* ── 继续展信链接 ── */
.read-more {
  display: inline-block;
  margin-top: 2rem;
  color: var(--color-accent);
  text-decoration: none;
  font-size: 0.9rem;
  border-bottom: 1px solid currentColor;
  padding-bottom: 1px;
  transition: opacity 0.2s;
}

.read-more:hover { opacity: 0.7; }

/* ── 文章末尾（署名区） ── */
.letter-footer {
  margin-top: 3rem;
  padding-top: 2rem;
  text-align: right;
}

.valediction {
  color: var(--color-meta);
  margin-bottom: 0.5rem;
}

.signature {
  margin-top: 1rem;
}

.signature-text {
  font-family: var(--font-signature);
  font-size: 1.5rem;
  color: var(--color-ink);
}

.signature-image {
  max-height: 3rem;
  display: inline-block;
}

.postscript {
  margin-top: 1.5rem;
  font-size: 0.9rem;
  color: var(--color-meta);
}

/* ── 信件导航 ── */
.letter-nav {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-fold);
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.letter-nav__link {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: var(--color-ink);
  max-width: 45%;
  transition: color 0.2s;
}

.letter-nav__link:hover {
  color: var(--color-accent);
}

.letter-nav__link--prev {
  align-items: flex-start;
}

.letter-nav__link--next {
  align-items: flex-end;
  text-align: right;
  margin-left: auto;
}

.letter-nav__label {
  font-size: 0.75rem;
  color: var(--color-meta);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.25rem;
}

.letter-nav__title {
  font-size: 0.95rem;
  line-height: 1.4;
}

/* ── 侧边栏（归档） ── */
.sidebar {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(320px, 85vw);
  padding: 3rem 1.25rem 2rem 1.5rem;
  background: #FDFBF7;
  z-index: 100;
  overflow-y: auto;
  box-shadow: -4px 0 20px rgba(0, 0, 0, 0.12);
  
  /* 默认隐藏，从右侧滑入 */
  transform: translateX(100%);
  transition: transform 0.35s ease;
}

.sidebar.is-open {
  transform: translateX(0);
}

.archive-title {
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-meta);
  margin-bottom: 1.25rem;
}

.year-toggle {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-meta);
  letter-spacing: 0.05em;
  padding: 0;
  margin-bottom: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.year-toggle::before {
  content: "▸";
  font-size: 0.6rem;
  transition: transform 0.2s;
}

.year-toggle[aria-expanded="true"]::before { transform: rotate(90deg); }

.month-list { margin-bottom: 1rem; }

.month-group {
  display: grid;
  grid-template-columns: 2rem 1fr;
  gap: 0 0.5rem;
  margin-bottom: 0.25rem;
}

.month-label {
  font-size: 0.7rem;
  color: var(--color-meta);
  padding-top: 0.15rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.month-group ul { list-style: none; }

.month-group a {
  display: flex;
  gap: 0.5rem;
  font-size: 0.8rem;
  color: var(--color-ink);
  text-decoration: none;
  padding: 0.15rem 0;
  line-height: 1.4;
  transition: color 0.15s;
}

.month-group a:hover { color: var(--color-accent); }
.month-group a[aria-current="page"] { color: var(--color-accent); font-weight: 600; }

.month-group time {
  flex-shrink: 0;
  color: var(--color-meta);
  font-size: 0.75rem;
}

/* ── 链接（正文内） ── */
.letter-body a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
  transition: text-underline-offset 0.2s, opacity 0.2s;
}

.letter-body a:hover {
  text-underline-offset: 5px;
  opacity: 0.75;
}

/* ── 称谓 ── */
.salutation {
  font-style: italic;
  color: var(--color-meta);
  margin-bottom: 1.5rem;
}

/* ── 侧边栏遮罩：与侧栏同时长淡入淡出 ── */
.sidebar-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.35);
  z-index: 99;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.35s ease, visibility 0s linear 0.35s;
}

.sidebar-overlay.is-visible {
  opacity: 1;
  visibility: visible;
  transition: opacity 0.35s ease;
}

/* ── 页脚 ── */
.site-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
  font-size: 0.8rem;
  color: var(--color-meta);
  max-width: calc(var(--width-content) + var(--width-sidebar) + 4rem);
  margin: 0 auto;
  width: 100%;
}

.back-to-top {
  color: var(--color-meta);
  text-decoration: none;
  font-size: 1rem;
}

.back-to-top:hover { color: var(--color-accent); }

/* ── Heti 覆盖（字体栈） ── */
.heti.heti--serif {
  font-family: var(--font-body);
}

/* ── 响应式：移动端 ── */
@media (max-width: 768px) {
  :root { --size-body: 16px; }

  .layout {
    padding: 0;
  }

  .paper {
    padding: 1.5rem 1.25rem 3rem;
    border-right: none;
    box-shadow: none;
    backdrop-filter: blur(10px) saturate(110%) brightness(1.02);
    -webkit-backdrop-filter: blur(10px) saturate(110%) brightness(1.02);
  }

  .sidebar {
    width: min(280px, 80vw);
  }

  .site-header { padding: 1rem 1.25rem; }

  /* 移动端标签调整 */
  .index-tab {
    padding: 0.6rem 0.3rem;
    font-size: 0.7rem;
    top: 4rem;
  }

  .index-tab.is-active {
    transform: translateX(calc(-1 * min(280px, 80vw) - 2px));
  }

  .sidebar {
    width: min(280px, 80vw);
  }
}

/* ============================================================
   Heti 深度集成
   ============================================================ */

/* ── night 模式桥接（Heti 用 prefers-color-scheme: dark，
       我们用 data-style="night"，需手动补齐） ── */
[data-style="night"] .heti blockquote {
  background-color: rgba(255, 255, 255, 0.06);
}
[data-style="night"] .heti hr {
  background-color: #404040;
}
[data-style="night"] .heti pre,
[data-style="night"] .heti code:not(pre > code) {
  background-color: rgba(255, 255, 255, 0.06);
  color: inherit;
}
[data-style="night"] .heti mark {
  background-color: rgba(255, 220, 0, 0.2);
  color: inherit;
}
[data-style="night"] .heti table thead {
  background-color: rgba(255, 255, 255, 0.06);
}
[data-style="night"] .heti a {
  color: var(--color-accent);
}

/* ── 让所有主题的 Heti 颜色继承我们的 CSS 变量 ── */
.heti {
  color: var(--color-ink);
}
.heti .heti-meta,
.heti-meta {
  color: var(--color-meta);
  font-size: 0.8em;
  font-style: normal;
  letter-spacing: 0.02em;
}
.heti a {
  color: var(--color-accent);
}

/* ── 诗词落款居中 ── */
.verse-byline {
  text-align: center;
  margin-top: -0.75rem;
  margin-bottom: 1.25rem;
}

/* ── Heti 字号类的显式定义（确保跨主题可见） ── */
.heti-x-large { font-size: 1.4em; }
.heti-large   { font-size: 1.15em; }
.heti-small   { font-size: 0.85em; }
.heti-x-small { font-size: 0.7em; }

/* ── 诗词版式：居中对齐 ── */
.heti--poetry {
  text-align: center;
}
.heti--poetry h2 {
  margin-bottom: 1.5rem;
}

/* ── 古文版式：缩进调整 ── */
.heti--ancient p {
  text-indent: 2em;
}

/* ── 竖排：容器高度限制 ── */
.heti--vertical {
  max-height: 42em;
  overflow-x: auto;
}

/* ── 多栏：栏间距 ── */
[class*="heti--columns-"] {
  column-gap: 2em;
  column-rule: 1px solid var(--color-fold);
}

/* ── shortcode 块与信件正文的间距 ── */
.letter-body .heti--poetry,
.letter-body .heti--ancient,
.letter-body .heti--vertical,
[class*="letter-body .heti--columns"] {
  margin-block: 2rem;
  padding: 1.5rem 2rem;
  border: 1px solid var(--color-fold);
  border-radius: 2px;
}

/* ============================================================
   Unified Dappled Layer — CSS-Tricks effect + theme-switch architecture
   ============================================================ */
:root {
  --dappled-paper-alpha: 0.72;
  --dappled-shadow-color: rgba(40, 50, 65, 0.62);
  --dappled-shadow-opacity: 1;
  --dappled-bokeh-color: rgba(255, 248, 230, 0.85);
  --dappled-bokeh-blur: 18px;
  --dappled-bokeh-opacity: 0.9;
  --dappled-wash-1: rgba(255, 246, 231, 0.84);
  --dappled-wash-2: rgba(255, 255, 255, 0.26);
  --dappled-grain-opacity: 0.12;
}

[data-style="warm"] {
  --dappled-paper-alpha: 0.70;
  --dappled-shadow-color: rgba(75, 45, 15, 0.64);
  --dappled-bokeh-color: rgba(255, 238, 200, 0.88);
  --dappled-bokeh-blur: 16px;
  --dappled-bokeh-opacity: 0.92;
  --dappled-wash-1: rgba(255, 225, 184, 0.88);
  --dappled-wash-2: rgba(255, 244, 222, 0.28);
  --dappled-grain-opacity: 0.14;
}

[data-style="sky"] {
  --dappled-paper-alpha: 0.72;
  --dappled-shadow-color: rgba(34, 66, 98, 0.54);
  --dappled-bokeh-color: rgba(240, 250, 255, 0.82);
  --dappled-bokeh-blur: 14px;
  --dappled-bokeh-opacity: 0.92;
  --dappled-wash-1: rgba(221, 241, 255, 0.82);
  --dappled-wash-2: rgba(255, 255, 255, 0.24);
  --dappled-grain-opacity: 0.11;
}

[data-style="night"] {
  --dappled-paper-alpha: 0.86;
  --dappled-shadow-color: rgba(0, 4, 14, 0.48);
  --dappled-shadow-opacity: 0.7;
  --dappled-bokeh-color: rgba(180, 200, 240, 0.35);
  --dappled-bokeh-blur: 22px;
  --dappled-bokeh-opacity: 0.65;
  --dappled-wash-1: rgba(74, 102, 148, 0.2);
  --dappled-wash-2: rgba(124, 170, 255, 0.06);
  --dappled-grain-opacity: 0.16;
}

[data-style="spring"] {
  --dappled-paper-alpha: 0.70;
  --dappled-shadow-color: rgba(32, 62, 36, 0.56);
  --dappled-bokeh-color: rgba(255, 245, 210, 0.82);
  --dappled-bokeh-blur: 16px;
  --dappled-bokeh-opacity: 0.88;
  --dappled-wash-1: rgba(228, 244, 214, 0.84);
  --dappled-wash-2: rgba(244, 255, 239, 0.24);
  --dappled-grain-opacity: 0.11;
}

body[data-dappled="off"] {
  --dappled-paper-alpha: 0.96;
}

.dappled-layer {
  position: fixed;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
  z-index: 0;
}

body[data-dappled="off"] .dappled-layer {
  display: none;
}

.dappled-layer__wash,
.dappled-layer__shapes,
.dappled-layer__grain {
  position: absolute;
  inset: 0;
}

.dappled-layer__wash {
  inset: -12% -12% -6% -14%;
  opacity: calc(var(--dappled-enabled) * 0.96);
  background:
    radial-gradient(42rem 28rem at 82% 4%, var(--dappled-wash-1) 0%, transparent 56%),
    radial-gradient(30rem 24rem at 58% 18%, var(--dappled-wash-2) 0%, transparent 58%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.08) 0%, transparent 72%);
  filter: blur(38px);
}

/* sky：上深下浅的天空蓝渐变——白云需要蓝天作底 */
[data-style="sky"] .dappled-layer__wash {
  background:
    linear-gradient(180deg, rgba(110, 165, 215, 0.55) 0%, rgba(150, 195, 235, 0.3) 40%, rgba(200, 228, 248, 0.1) 75%, transparent 100%),
    radial-gradient(42rem 28rem at 82% 4%, rgba(255, 255, 255, 0.35) 0%, transparent 56%);
}

/* 枝影由 SVG 绘制（锐/柔焦平面在 SVG 分组滤镜里），容器不再整体模糊 */
.dappled-layer__shadows {
  position: absolute;
  inset: -8%;
  opacity: calc(var(--dappled-enabled) * var(--dappled-shadow-opacity, 1));
  animation: dappledDrift 36s ease-in-out infinite alternate;
}

.dappled-svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  filter: url(#dw-wind);
}

/* Firefox 的 SVG 位移滤镜走 CPU，太贵：关掉风动，保留摇曳动画 */
@supports (-moz-appearance: none) {
  .dappled-svg {
    filter: none;
  }
}

/* 风的节奏：阵风急推 → 回弹 → 余颤 → 静息（非对称，避免钟摆/水波感）
   整树慢摇、一级枝独立摆动、垂枝大幅拂动，相位由 JS 随机化 */
@keyframes treeSway {
  0%, 100% { transform: rotate(-0.55deg); }
  52%      { transform: rotate(1.05deg); }
  70%      { transform: rotate(0.3deg); }
  85%      { transform: rotate(0.7deg); }
}

@keyframes branchSway {
  0%, 100% { transform: rotate(-0.85deg); }
  48%      { transform: rotate(1.35deg); }
  66%      { transform: rotate(0.2deg); }
  83%      { transform: rotate(0.8deg); }
}

@keyframes strandSway {
  0%, 100% { transform: rotate(-1.0deg); }
  45%      { transform: rotate(1.5deg); }
  64%      { transform: rotate(0.25deg); }
  82%      { transform: rotate(0.85deg); }
}

/* 云影平移：极慢的横向漂移（sky 主题） */
@keyframes cloudDrift {
  from { transform: translate3d(-7px, 0, 0); }
  to   { transform: translate3d(7px, 0, 0); }
}

/* screen 混合让光池真正"发亮"而非盖一层白（CSS-Tricks dappled light 的思路：
   暗调铺底，光从叶隙透出来发光） */
.dappled-layer__bokeh {
  position: absolute;
  inset: -8%;
  filter: blur(var(--dappled-bokeh-blur, 18px));
  mix-blend-mode: screen;
  opacity: calc(var(--dappled-enabled) * var(--dappled-bokeh-opacity, 0.7));
  animation: dappledDrift 30s ease-in-out -8s infinite alternate;
}

/* Warm bokeh light spots */
.dappled-bokeh {
  position: absolute;
  border-radius: 50%;
  background: radial-gradient(
    circle,
    var(--dappled-bokeh-color) 0%,
    transparent 72%
  );
}

.dappled-layer__grain {
  background-image:
    radial-gradient(rgba(255, 255, 255, 0.08) 0.55px, transparent 0.8px),
    radial-gradient(rgba(31, 39, 49, 0.05) 0.55px, transparent 0.8px);
  background-position: 0 0, 9px 12px;
  background-size: 18px 18px, 23px 23px;
  opacity: calc(var(--dappled-enabled) * var(--dappled-grain-opacity));
  mix-blend-mode: soft-light;
}

.layout,
.site-header,
.site-footer {
  position: relative;
  z-index: 1;
}

.paper {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  background: linear-gradient(
    180deg,
    rgba(var(--color-paper-rgb), calc(var(--dappled-paper-alpha) + 0.05)) 0%,
    rgba(var(--color-paper-rgb), var(--dappled-paper-alpha)) 38%,
    rgba(var(--color-paper-rgb), calc(var(--dappled-paper-alpha) - 0.04)) 100%
  );
  backdrop-filter: blur(14px) saturate(118%) brightness(1.02);
  -webkit-backdrop-filter: blur(14px) saturate(118%) brightness(1.02);
}

.paper::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.16) 0%, transparent 28%, rgba(255, 255, 255, 0.08) 100%);
}

.paper > * {
  position: relative;
  z-index: 1;
}

@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .paper {
    background: linear-gradient(
      180deg,
      rgba(var(--color-paper-rgb), 0.92) 0%,
      rgba(var(--color-paper-rgb), 0.9) 100%
    );
  }
}

@keyframes dappledDrift {
  0% { transform: translate3d(0, 0, 0) scale(1); }
  100% { transform: translate3d(-1.8rem, 1.2rem, 0) scale(1.02); }
}

@media (max-width: 768px) {
  .dappled-layer__wash {
    inset: -12% -18% -2% -22%;
  }

  .dappled-layer__shadows {
    --dappled-shadow-opacity: 0.8;
  }

  .dappled-layer__bokeh {
    --dappled-bokeh-blur: 20px;
    --dappled-bokeh-opacity: 0.5;
  }

  .dappled-layer__grain {
    opacity: calc(var(--dappled-enabled) * 0.09);
  }

  .paper {
    backdrop-filter: blur(10px) saturate(110%) brightness(1.02);
    -webkit-backdrop-filter: blur(10px) saturate(110%) brightness(1.02);
  }
}

@media (prefers-reduced-motion: reduce) {
  .dappled-layer__shadows,
  .dappled-layer__bokeh,
  .dappled-layer__grain {
    animation: none;
  }

  .dappled-svg {
    filter: none;
  }

  .dappled-svg * {
    animation: none !important;
  }
}

@media (prefers-contrast: more) {
  .dappled-layer {
    display: none;
  }
}

/* ── Guestbook ── */
.page-guestbook .paper {
  width: 100%;
}

.guestbook-intro,
.guestbook-help,
.guestbook-status,
.guestbook-unavailable {
  color: var(--color-meta);
}

.guestbook-compose,
.guestbook-entries {
  margin-top: 2.5rem;
}

.guestbook-compose h2,
.guestbook-entries h2 {
  font-family: var(--font-title);
  font-size: 1.25rem;
  font-weight: 400;
  margin-bottom: 1rem;
}

.guestbook-form {
  display: grid;
  gap: 1rem;
}

.guestbook-form__identity {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.8rem;
}

.guestbook-form__footer {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.guestbook-form p {
  margin-block: 0;
}

.guestbook-error:empty,
.guestbook-status:empty {
  display: none;
}

.guestbook-field {
  display: grid;
  gap: 0.3rem;
}

.guestbook-field label {
  font-size: 0.9rem;
  color: var(--color-ink);
}

.guestbook-field input,
.guestbook-field textarea {
  width: 100%;
  border: 1px solid var(--color-fold);
  border-radius: 2px;
  background: rgba(var(--color-paper-rgb), 0.55);
  color: var(--color-ink);
  font: inherit;
  padding: 0.55rem 0.65rem;
}

.guestbook-field textarea {
  resize: vertical;
}

.guestbook-field input:focus,
.guestbook-field textarea:focus,
.guestbook-submit:focus,
.correspondence-compose > summary:focus {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.guestbook-help,
.guestbook-error,
.guestbook-status,
.guestbook-unavailable {
  font-size: 0.85rem;
}

.guestbook-error,
.guestbook-status[data-kind="error"] {
  color: #9F2A2A;
}

.guestbook-status[data-kind="success"] {
  color: var(--color-accent);
}

.guestbook-submit,
.guestbook-empty__action,
.correspondence-compose > summary {
  justify-self: start;
  border: 1px solid var(--color-accent);
  border-radius: 2px;
  background: transparent;
  color: var(--color-accent);
  cursor: pointer;
  font: inherit;
  padding: 0.45rem 0.9rem;
  text-decoration: none;
}

.correspondence {
  margin-top: 4rem;
}

.correspondence-compose,
.correspondence-header {
  border-top: 1px solid var(--color-fold);
  padding-top: 2rem;
}

.correspondence-compose > summary {
  display: inline-block;
  list-style: none;
}

.correspondence-compose > summary::-webkit-details-marker {
  display: none;
}

.correspondence-compose > .guestbook-form {
  margin-top: 1.25rem;
}

.correspondence-header h2 {
  font-family: var(--font-title);
  font-size: 1.45rem;
  font-weight: 400;
}

.correspondence-empty {
  color: var(--color-meta);
  margin-top: 0.75rem;
}

.correspondence > .guestbook-form {
  margin-top: 1.25rem;
}

.correspondence ol.guestbook-list {
  gap: 0;
  list-style: none;
  margin-top: 1.25rem;
  padding-left: 0;
}

.correspondence .guestbook-entry {
  border-bottom: 1px solid var(--color-fold);
  border-top: 0;
  padding: 1.6rem 0;
}

.correspondence .guestbook-entry:last-child {
  border-bottom: 0;
}

.guestbook-entry__meta {
  color: var(--color-meta);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
}

.correspondence .guestbook-message {
  margin-top: 0.45rem;
}

.correspondence .guestbook-reply {
  margin-left: 3rem;
}

.correspondence .guestbook-reply span {
  color: var(--color-meta);
  font-size: 0.78rem;
}

.guestbook-submit:disabled {
  cursor: wait;
  opacity: 0.65;
}

.guestbook-list {
  display: grid;
  gap: 1.5rem;
  list-style: none;
}

.guestbook-entry {
  border-top: 1px solid var(--color-fold);
  padding-top: 1.25rem;
}

.guestbook-entry__header {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.guestbook-entry__header h3 {
  font-family: var(--font-title);
  font-size: 1.1rem;
  font-weight: 400;
}

.guestbook-entry__header a {
  color: var(--color-ink);
  text-decoration: none;
}

.guestbook-entry__header a:hover {
  color: var(--color-accent);
}

.guestbook-entry__header time {
  color: var(--color-meta);
  font-size: 0.85rem;
  white-space: nowrap;
}

.guestbook-message,
.guestbook-reply p {
  white-space: pre-wrap;
  text-wrap: pretty;
}

.guestbook-reply {
  border-left: 2px solid var(--color-fold);
  margin-top: 1rem;
  padding-left: 1rem;
}

.guestbook-reply h4,
.guestbook-reply h2 {
  color: var(--color-meta);
  font-size: 0.9rem;
  font-weight: 400;
  margin-bottom: 0.35rem;
}

.guestbook-empty {
  border-top: 1px solid var(--color-fold);
  padding-top: 1.25rem;
}

.guestbook-empty p {
  margin-bottom: 0.75rem;
}

@media (max-width: 768px) {
  .guestbook-form__identity {
    grid-template-columns: 1fr;
  }

  .correspondence .guestbook-reply {
    margin-left: 1rem;
  }

  .guestbook-entry__header {
    display: block;
  }
}