.page-about {
  --about-line-green: #39ff14;
  --about-line-dim: #444;
  --about-bg-deep: #1a1a1a;
  --about-bg-blue: #1e3a5f;
  --about-bg-maroon: #8b0000;
  --about-bg-purple: #4a2e5a;
  --about-card-glow: rgba(255, 102, 0, 0.12);

  background: var(--tt-bg);
  color: var(--tt-fg);
  font-family: var(--tt-font-body);
  line-height: 1.6;
}

.page-about .about-frame {
  max-width: var(--tt-max-w);
  margin: 0 auto;
  display: block;
  padding: 18px 16px 48px;
}

/* ===== 左侧目录栏 ===== */
.page-about .about-aside {
  border-bottom: 1px solid var(--tt-border);
  padding-bottom: 20px;
  margin-bottom: 24px;
}

.page-about .about-aside__label {
  display: block;
  font-family: var(--tt-font-tag);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--tt-fg-dim);
  border-bottom: 1px solid var(--about-line-green);
  padding-bottom: 8px;
  margin-bottom: 14px;
}

.page-about .about-nav {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 20px;
}

.page-about .about-nav__link {
  font-family: var(--tt-font-tag);
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--tt-fg);
  text-decoration: none;
  padding: 6px 10px;
  border: 1px solid var(--tt-border);
  background: rgba(0, 0, 0, 0.3);
  transition: background 150ms ease, border-color 150ms ease;
}

.page-about .about-nav__link span {
  color: var(--tt-orange);
  margin-right: 6px;
  font-weight: 700;
}

.page-about .about-nav__link:hover,
.page-about .about-nav__link:focus-visible {
  border-color: var(--about-line-green);
  background: var(--about-bg-blue);
  outline: none;
}

.page-about .about-aside__stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0;
  margin: 0 0 18px;
  border-top: 1px solid var(--tt-border);
  border-left: 1px solid var(--tt-border);
}

.page-about .about-stat {
  padding: 10px 12px;
  border-right: 1px solid var(--tt-border);
  border-bottom: 1px solid var(--tt-border);
}

.page-about .about-stat dt {
  font-family: var(--tt-font-tag);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--tt-fg-dim);
  margin-bottom: 4px;
}

.page-about .about-stat dd {
  margin: 0;
  font-family: var(--tt-font-head);
  font-size: 1.55rem;
  font-weight: 900;
  color: var(--tt-orange);
  line-height: 1.1;
}

.page-about .about-aside__foot .tt-btn {
  width: 100%;
  justify-content: center;
}

/* ===== 右栏结构 ===== */
.page-about .about-content {
  min-width: 0;
}

.page-about .about-scroll-progress {
  position: sticky;
  top: 0;
  height: 2px;
  background: var(--about-line-green);
  transform: scaleX(var(--tt-progress, 0));
  transform-origin: left;
  z-index: 5;
}

.page-about .about-breadcrumb {
  margin-bottom: 20px;
}

.page-about .about-breadcrumb a {
  color: var(--tt-orange);
  text-decoration: none;
}

.page-about .about-breadcrumb a:hover {
  color: var(--about-line-green);
}

.page-about .about-breadcrumb__sep {
  color: var(--tt-fg-dim);
  margin: 0 8px;
}

/* ===== 首屏导语 ===== */
.page-about .about-hero {
  padding: 8px 0 26px;
  border-bottom: 1px solid var(--tt-border);
  margin-bottom: 28px;
}

.page-about .about-hero h1 {
  font-family: var(--tt-font-head);
  font-size: 1.9rem;
  line-height: 1.25;
  font-weight: 900;
  text-transform: uppercase;
  color: var(--tt-fg);
  margin: 0 0 12px;
  letter-spacing: 0.01em;
}

.page-about .about-hero__lead {
  font-size: 0.9rem;
  color: var(--tt-fg-dim);
  max-width: 58em;
  margin: 0;
}

.page-about .about-hero__num {
  color: var(--tt-orange);
  font-size: 1.1rem;
  font-weight: 700;
}

/* ===== 区块通用 ===== */
.page-about .about-section {
  padding: 20px 0 26px;
  margin-bottom: 26px;
  border-top: 2px solid var(--tt-border);
  position: relative;
}

.page-about .about-section__top {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 16px;
}

.page-about .about-section__top h2 {
  font-family: var(--tt-font-head);
  font-size: 1.3rem;
  font-weight: 900;
  text-transform: uppercase;
  margin: 0;
  line-height: 1.3;
}

.page-about .tt-panel-label {
  flex-shrink: 0;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-family: var(--tt-font-tag);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--tt-orange);
  border-left: 1px solid var(--tt-orange);
  padding-left: 6px;
  min-height: 42px;
  margin-top: 4px;
}

/* ===== 01 站点结构 ===== */
.page-about .about-section--structure {
  border-top-color: var(--tt-yellow);
}

.page-about .about-structure {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.page-about .about-tree {
  flex: 1;
  min-width: 0;
}

.page-about .about-tree__root {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--about-bg-blue);
  border-left: 4px solid var(--about-line-green);
  padding: 12px 16px;
  margin-bottom: 14px;
}

.page-about .about-tree__root-name {
  font-family: var(--tt-font-head);
  font-size: 1.1rem;
  font-weight: 900;
  letter-spacing: 0.04em;
  color: var(--tt-fg);
}

.page-about .about-tree__root-meta {
  font-family: var(--tt-font-tag);
  font-size: 0.76rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--tt-yellow);
}

.page-about .about-tree__branches {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
}

.page-about .tree-branch {
  background: rgba(0, 0, 0, 0.32);
  border: 1px solid var(--tt-border);
  border-top: 3px solid var(--tt-orange);
  padding: 10px 12px;
  transition: border-color 150ms ease, background 150ms ease;
}

.page-about .tree-branch:hover {
  border-color: var(--tt-yellow);
  background: rgba(30, 58, 95, 0.35);
}

.page-about .tree-branch__top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 6px;
}

.page-about .tree-branch__name {
  font-family: var(--tt-font-head);
  font-size: 1.05rem;
  font-weight: 900;
  letter-spacing: 0.04em;
  color: var(--tt-yellow);
}

.page-about .tree-branch__meta {
  font-family: var(--tt-font-tag);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--tt-orange);
  white-space: nowrap;
}

.page-about .tree-branch__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px 8px;
}

.page-about .tree-branch__list li {
  font-size: 0.76rem;
  color: var(--tt-fg-dim);
  border: 1px solid transparent;
  padding: 2px 4px;
  transition: color 150ms, border-color 150ms;
}

.page-about .tree-branch__list li::before {
  content: "▪";
  color: var(--about-line-green);
  margin-right: 4px;
  font-size: 0.6rem;
}

.page-about .tree-branch__list li:hover {
  color: var(--tt-fg);
  border-color: var(--tt-border);
}

.page-about .about-structure__img {
  width: 100%;
  max-width: 400px;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--about-line-green);
  align-self: center;
}

/* ===== 02 收录流程 ===== */
.page-about .about-section--workflow {
  background: var(--about-bg-maroon);
  margin-left: -16px;
  margin-right: -16px;
  padding-left: 16px;
  padding-right: 16px;
  border-top: 2px solid var(--tt-orange);
}

.page-about .about-workflow {
  position: relative;
}

.page-about .workflow-step {
  position: relative;
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 14px;
  padding-bottom: 26px;
}

.page-about .workflow-step:last-child {
  padding-bottom: 4px;
}

.page-about .workflow-step:not(:last-child)::before {
  content: "";
  position: absolute;
  left: 25px;
  top: 52px;
  bottom: 4px;
  width: 2px;
  background: rgba(255, 255, 255, 0.25);
}

.page-about .workflow-step__num {
  width: 52px;
  height: 52px;
  background: var(--tt-orange);
  color: #1a1a1a;
  font-family: var(--tt-font-head);
  font-size: 1.25rem;
  font-weight: 900;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 0 3px rgba(255, 102, 0, 0.25);
}

.page-about .workflow-step__body h3 {
  font-family: var(--tt-font-tag);
  font-size: 0.84rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--tt-fg);
  margin: 0 0 4px;
  font-weight: 700;
}

.page-about .workflow-step__body p {
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.82);
  margin: 0;
  max-width: 46em;
}

/* ===== 03 更新周期 ===== */
.page-about .about-section--cadence {
  border-top-color: var(--tt-cyan);
}

.page-about .about-cadence {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.page-about .cadence-track {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 18px;
  padding: 6px 0 6px 26px;
  border-left: 2px solid var(--tt-border);
}

.page-about .cadence-point {
  position: relative;
  padding-left: 18px;
}

.page-about .cadence-point__dot {
  position: absolute;
  left: -31px;
  top: 4px;
  width: 12px;
  height: 12px;
  background: var(--tt-fg-dim);
  border: 2px solid var(--tt-bg);
  box-shadow: 0 0 0 1px var(--tt-fg-dim);
}

.page-about .cadence-point--hot .cadence-point__dot {
  background: var(--tt-red);
  box-shadow: 0 0 0 1px var(--tt-red), 0 0 8px rgba(255, 51, 51, 0.45);
}

.page-about .cadence-point--daily .cadence-point__dot {
  background: var(--tt-orange);
  box-shadow: 0 0 0 1px var(--tt-orange), 0 0 8px rgba(255, 102, 0, 0.4);
}

.page-about .cadence-point--weekly .cadence-point__dot {
  background: var(--tt-cyan);
  box-shadow: 0 0 0 1px var(--tt-cyan), 0 0 8px rgba(102, 204, 255, 0.4);
}

.page-about .cadence-point__interval {
  display: block;
  font-family: var(--tt-font-head);
  font-size: 1.05rem;
  font-weight: 900;
  text-transform: uppercase;
  color: var(--tt-fg);
  margin-bottom: 4px;
}

.page-about .cadence-point__label {
  font-size: 0.8rem;
  color: var(--tt-fg-dim);
  line-height: 1.5;
}

.page-about .about-cadence__img {
  width: 100%;
  max-width: 600px;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--tt-border);
  align-self: center;
}

/* ===== 04 版本演进 ===== */
.page-about .about-section--versions {
  background: var(--about-bg-purple);
  margin-left: -16px;
  margin-right: -16px;
  padding-left: 16px;
  padding-right: 16px;
  border-top: 2px solid var(--about-line-green);
}

.page-about .about-versions {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.page-about .about-versions__cover {
  width: 100%;
  max-width: 300px;
  height: auto;
  object-fit: cover;
  border: 1px solid rgba(255, 255, 255, 0.3);
  align-self: flex-start;
}

.page-about .about-version-line {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
  flex: 1;
}

.page-about .about-version-line::before {
  content: "";
  position: absolute;
  left: 66px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: repeating-linear-gradient(
    to bottom,
    var(--about-line-green) 0,
    var(--about-line-green) 4px,
    transparent 4px,
    transparent 8px
  );
  opacity: 0.4;
}

.page-about .version-item {
  position: relative;
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: 16px;
  padding: 10px 0;
}

.page-about .version-item__code {
  font-family: var(--tt-font-head);
  font-size: 0.98rem;
  font-weight: 900;
  color: var(--about-line-green);
  letter-spacing: 0.04em;
  z-index: 1;
  background: var(--about-bg-purple);
  display: inline-block;
  padding: 2px 0;
}

.page-about .version-item__note {
  font-size: 0.83rem;
  color: rgba(255, 255, 255, 0.85);
  padding-top: 4px;
}

/* ===== 05 检索方式 ===== */
.page-about .about-section--search {
  border-top-color: var(--tt-orange);
}

.page-about .about-search-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
}

.page-about .search-route {
  border: 1px solid var(--tt-border);
  border-bottom: 3px solid var(--tt-border);
  background: rgba(30, 58, 95, 0.3);
  padding: 14px;
  transition: border-color 150ms ease, background 150ms ease;
}

.page-about .search-route:hover {
  border-color: var(--tt-orange);
  background: rgba(255, 102, 0, 0.1);
}

.page-about .search-route__icon {
  display: block;
  font-size: 1.3rem;
  color: var(--tt-orange);
  margin-bottom: 8px;
  font-weight: 700;
}

.page-about .search-route h3 {
  font-family: var(--tt-font-tag);
  font-size: 0.86rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--tt-fg);
  margin: 0 0 6px;
  font-weight: 700;
}

.page-about .search-route p {
  font-size: 0.78rem;
  color: var(--tt-fg-dim);
  margin: 0;
  line-height: 1.5;
}

/* ===== 相关入口 ===== */
.page-about .about-elsewhere {
  margin-top: 12px;
  border: 1px solid var(--tt-border);
  border-left: 4px solid var(--tt-orange);
  background: var(--tt-gray-panel);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.page-about .about-elsewhere__intro h2 {
  font-family: var(--tt-font-head);
  font-size: 1.1rem;
  font-weight: 900;
  text-transform: uppercase;
  margin: 6px 0 6px;
  color: var(--tt-fg);
}

.page-about .about-elsewhere__intro p {
  margin: 0;
  font-size: 0.82rem;
  color: var(--tt-fg-dim);
}

.page-about .about-elsewhere__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* ===== 平板 ===== */
@media (min-width: 560px) {
  .page-about .about-frame {
    padding-left: 24px;
    padding-right: 24px;
  }

  .page-about .about-section--workflow,
  .page-about .about-section--versions {
    margin-left: -24px;
    margin-right: -24px;
    padding-left: 24px;
    padding-right: 24px;
  }

  .page-about .about-tree__branches {
    grid-template-columns: repeat(2, 1fr);
  }

  .page-about .about-search-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .page-about .about-nav {
    flex-direction: column;
    gap: 0;
  }

  .page-about .about-nav__link {
    border: none;
    border-bottom: 1px solid var(--tt-border);
    background: transparent;
    padding: 9px 4px;
    display: flex;
    align-items: center;
  }
}

@media (min-width: 760px) {
  .page-about .about-search-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .page-about .about-structure {
    flex-direction: row;
    align-items: flex-start;
  }

  .page-about .about-structure__img {
    width: 340px;
    flex-shrink: 0;
  }

  .page-about .about-cadence {
    flex-direction: row;
    align-items: center;
  }

  .page-about .about-cadence__img {
    width: 50%;
    max-width: 600px;
    flex-shrink: 0;
  }

  .page-about .cadence-track {
    flex-direction: row;
    border-left: none;
    border-top: 2px solid var(--tt-border);
    padding: 26px 0 0;
    gap: 0;
  }

  .page-about .cadence-point {
    flex: 1;
    padding: 0;
    text-align: left;
  }

  .page-about .cadence-point__dot {
    left: 0;
    top: -32px;
  }

  .page-about .cadence-point__label br {
    display: none;
  }
}

@media (min-width: 900px) {
  .page-about .about-frame {
    display: grid;
    grid-template-columns: 260px 1fr;
    gap: 38px;
    padding: 36px 40px 56px;
  }

  .page-about .about-aside {
    border-bottom: none;
    border-right: 1px solid var(--tt-border);
    padding-bottom: 0;
    margin-bottom: 0;
    padding-right: 26px;
  }

  .page-about .about-aside__inner {
    position: sticky;
    top: 96px;
  }

  .page-about .about-section--workflow {
    margin-left: -40px;
    margin-right: -40px;
    padding-left: 40px;
    padding-right: 40px;
  }

  .page-about .about-section--versions {
    margin-left: -40px;
    margin-right: -40px;
    padding-left: 40px;
    padding-right: 40px;
  }

  .page-about .about-elsewhere {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }

  .page-about .about-elsewhere__links {
    flex-shrink: 0;
  }
}

@media (min-width: 1100px) {
  .page-about .about-hero h1 {
    font-size: 2.4rem;
  }

  .page-about .about-section__top h2 {
    font-size: 1.45rem;
  }

  .page-about .about-structure__img {
    width: 400px;
  }
}