@font-face {
  font-family: "Alibaba PuHuiTi";
  src: url("assets/AlibabaPuHuiTi-Regular.woff2") format("woff2");
  font-weight: 300 400;
  font-display: swap;
}

@font-face {
  font-family: "Alibaba PuHuiTi";
  src: url("assets/AlibabaPuHuiTi-Medium.woff2") format("woff2");
  font-weight: 500 700;
  font-display: swap;
}

* { box-sizing: border-box; }
html {
  --case-header-height: var(--navigation-height);
  --case-offset: var(--case-header-height);
  scrollbar-gutter: stable;
  scroll-padding-top: var(--case-offset);
  scroll-behavior: smooth;
  background: var(--color-background-surface);
}

body {
  margin: 0;
  background: var(--color-background-surface);
  color: var(--color-text-primary);
  font: 400 16px/1.5 var(--font-body);
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }
a:focus-visible, [tabindex="-1"]:focus-visible {
  outline: 2px solid var(--color-border-focus);
  outline-offset: -2px;
  border-radius: var(--radius-sm);
}

.case-skip {
  position: fixed;
  z-index: 5;
  inset: var(--space-sm) auto auto var(--space-sm);
  transform: translateY(-200%);
  background: var(--color-background-surface);
  padding: var(--space-sm) var(--space-lg);
}
.case-skip:focus { transform: none; }

.case-header {
  --navigation-surface: transparent;
  position: sticky;
  z-index: 3;
  top: 0;
  height: var(--case-header-height);
  background: var(--color-background-surface);
  border-block-end: 1px solid var(--color-border-default);
}

.case-main {
  --case-content-start: var(--navigation-inline-start);
  --case-sidebar-padding: clamp(20px, 2.8vw, 44px);
  --case-sidebar-text-width: clamp(216px, 21vw, 320px);
  display: grid;
  grid-template-columns:
    max(clamp(248px, 27.4vw, 400px), calc(var(--case-content-start) + var(--case-sidebar-text-width) + var(--case-sidebar-padding)))
    minmax(0, 1fr);
  align-items: start;
}
.case-panel {
  position: sticky;
  top: var(--case-header-height);
  z-index: 2;
  min-height: calc(100dvh - var(--case-header-height));
  max-height: calc(100dvh - var(--case-header-height));
  overflow: auto;
  padding-block: var(--case-sidebar-padding);
  padding-inline: var(--case-content-start) var(--case-sidebar-padding);
  background: var(--color-background-surface);
  box-shadow: 3px 0 14px var(--color-shadow-soft);
}
.case-panel[hidden] { display: none; }
.case-back {
  --back-icon-size: 20px;
  display: inline-grid;
  place-items: center;
  width: var(--control-height);
  height: var(--control-height);
  margin-inline-start: -12px;
  border-radius: var(--radius-full);
  color: var(--color-text-secondary);
}
.case-back svg { display: block; width: var(--back-icon-size); height: var(--back-icon-size); }
.case-back:focus-visible { border-radius: var(--radius-full); }
#case-title {
  margin: var(--space-sm) 0 0;
  font-family: var(--font-heading);
  font-size: clamp(24px, 2.1vw, 34px);
  font-synthesis: none;
  line-height: var(--case-title-line-height, 1.18);
  font-weight: 700;
}
#case-title span { display: block; }
.case-description {
  color: var(--color-text-secondary);
  font-size: 14px;
  line-height: 1.65;
}
.case-description { margin: var(--space-2xl) 0 0; }
.case-chapters { margin-top: clamp(24px, 4vh, 48px); }
.case-chapters ol { list-style: none; margin: 0; padding: 0; }
.case-chapters li { position: relative; }
.case-chapters li:not(:last-child)::after {
  content: "";
  position: absolute;
  top: calc(50% + 7px);
  bottom: calc(-50% + 7px);
  left: 4px;
  width: 1px;
  background: var(--color-border-default);
  pointer-events: none;
}
.case-chapters a {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  min-height: 54px;
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: 14px;
  white-space: nowrap;
}
.case-chapters a::before {
  content: "";
  width: 9px;
  height: 9px;
  flex: 0 0 auto;
  border: 1px solid var(--color-text-secondary);
  border-radius: var(--radius-full);
  background: var(--color-background-surface);
}
.case-chapters a[aria-current="location"] { color: var(--color-text-primary); font-weight: 600; }
.case-chapters a[aria-current="location"]::before { background: var(--color-text-primary); }

.case-links { margin-top: clamp(var(--space-2xl), 4vh, 48px); }
.case-links ul {
  display: flex;
  flex-direction: column;
  list-style: none;
  margin: 0;
  padding: 0;
}
.case-links a {
  display: inline-flex;
  align-items: center;
  min-height: var(--control-height);
  color: var(--color-text-primary);
  font-size: 14px;
  text-decoration: none;
}
.case-link-label {
  display: inline-flex;
  gap: var(--space-sm);
  border-block-end: 1px solid currentColor;
}

.case-pages, .case-pages section { min-width: 0; }
.case-pages section { position: relative; }
.case-pages section:last-child { min-height: calc(100dvh - var(--case-offset)); }
.case-pages section:focus-visible { outline: none; }
.case-pages section:focus-visible::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  border-block-start: 2px solid var(--color-border-focus);
  pointer-events: none;
}
.case-pages img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  border-block-end: 1px solid var(--color-border-default);
}
.case-main:has(.case-panel[hidden]) { display: block; }
.case-empty { margin: 0; padding: var(--space-2xl); }

@media (hover: hover) {
  .case-chapters a:hover { text-decoration: underline; }
  .case-links a:hover { color: var(--color-brand-primary); }
  .case-back:hover { background: var(--color-background-canvas); }
}

@container portfolio (width <= 960px) {
  .case-main { display: block; }
  .case-panel {
    --case-title-size: clamp(20px, 3.05vw, 30px);
    --case-title-line-height: 1.18;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: var(--space-xl);
    padding-block: var(--space-lg);
    padding-inline-end: clamp(20px, 4.5vw, 44px);
    box-shadow: 0 4px 16px var(--color-shadow-soft);
    min-height: 0;
    max-height: none;
    overflow: visible;
  }
  .case-meta {
    display: grid;
    flex: 1 0 min(100%, 210px);
    grid-template-columns: var(--control-height) minmax(0, 1fr);
    align-items: center;
    column-gap: var(--space-xs);
  }
  .case-back { margin-inline-start: 0; }
  #case-title { margin-top: 0; font-size: var(--case-title-size); }
  .case-description { display: none; }
  .case-links { margin: 0; }
  .case-links ul { flex-direction: row; flex-wrap: wrap; column-gap: var(--space-xl); }
  .case-chapters { flex: 1 0 min(100%, 230px); margin: 0; }
  .case-chapters ol { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .case-chapters li:not(:last-child)::after {
    left: calc(50% + 9px);
    right: calc(-50% + 9px);
    top: 10px;
    bottom: auto;
    width: auto;
    height: 1px;
  }
  .case-chapters a {
    flex-direction: column;
    gap: var(--space-xs);
    min-height: var(--control-height);
    padding-top: 6px;
  }
}

@container portfolio (520px < width <= 960px) {
  .case-meta { align-items: start; }
  .case-back {
    transform: translateY(calc((var(--case-title-size) * var(--case-title-line-height) - var(--control-height)) / 2));
  }
}

@container portfolio (width <= 520px) {
  .case-main { --case-content-start: var(--space-2xl); }
  .case-panel {
    --case-title-size: clamp(16px, 4.2vw, 21px);
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-xs);
    padding-inline-end: var(--space-lg);
  }
  #case-title { display: flex; flex-wrap: wrap; column-gap: var(--space-xs); }
  .case-chapters a { font-size: 13px; }
}

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