/* -----------------------------
   1) Font & Resets
----------------------------- */
@font-face {
  font-family: "InterVar";
  src: url("fonts/Inter-Variable.woff2") format("woff2");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
:root{
  --bg:#fafafa;
  --ink:#141418;
  --muted:#6b7280;
  --line:#e5e7eb;
  --card:#ffffff;
  --accent:#0f766e;
  --accent-ink:#ecfeff;
  --radius:14px;
  --gap:20px;
  --max:1200px;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  background:var(--bg);
  color:var(--ink);
  font-family: InterVar, system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Liberation Sans", sans-serif;
  line-height:1.6;
}

/* -----------------------------
   2) Global Grid Layout
   Areas: header | sidebar | main | footer
----------------------------- */
body{
  display:grid;
  grid-template-columns: 200px minmax(0,1fr);
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "header header"
    "sidebar main"
    "footer footer";
  min-height:100dvh;
}
body.no-sidebar{
  grid-template-columns: minmax(0,1fr);
  grid-template-areas:
    "header"
    "main"
    "footer";
}

/* -----------------------------
   3) Header + Nav (Flex)
----------------------------- */
.site-header{
  grid-area: header;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap: var(--gap);
  padding:16px 24px;
  border-bottom:1px solid var(--line);
  background:#fff;
}
.logo{
  font-weight:800;
  letter-spacing:.3px;
  text-decoration:none;
  color:var(--ink);
}
.main-nav .nav-list{
  display:flex;               /* Flex 单轴：菜单 */
  gap:16px;
  list-style:none;
  margin:0;
  padding:0;
}
.main-nav a{
  text-decoration:none;
  color:var(--ink);
  padding:8px 10px;
  border-radius:8px;
}
.main-nav a:hover,
.nav-list .is-active a,
.main-nav a[aria-current="page"]{
  background:var(--ink);
  color:#fff;
}

/* -----------------------------
   4) Sidebar
----------------------------- */
.site-sidebar{
  grid-area: sidebar;
  border-right:1px solid var(--line);
  background:#fff;
  padding:8px;
  font-size: 14px; 
}
.side-list{
  list-style:none;
  margin:0; padding:0;
  display:flex; flex-direction:column; gap:4px;
  font-size: 14px;
}
.side-list a{
  display:block;
  padding:6px 8px;
  color:var(--ink);
  text-decoration:none;
  border-radius:6px;
  font-size: 14px;  
}
.side-list .is-active a,
.side-list a:hover{ background:#f3f4f6; }

/* -----------------------------
   5) Main & Footer
----------------------------- */
.site-main{
  grid-area: main;
  max-width: var(--max);
  width: 100%;
  margin: 0 auto;
  padding: 24px;
}
.site-footer{
  grid-area: footer;
  padding: 18px 24px;
  border-top:1px solid var(--line);
  color:var(--muted);
  background:#fff;
}

/* -----------------------------
   6) Hero (Home)
----------------------------- */
.hero{
  text-align:center;
  margin: 12px auto 18px;
}
.hero__title{ 
  font-size: clamp(28px, 3.5vw, 44px);
  line-height:1.2;
  margin:0 0 6px;
}
.hero__subtitle{ 
  color:var(--muted); 
  margin:0;
}
.hero-body {
  display: flex;               
  align-items: flex-start;     
  justify-content: center;     
  gap: 2rem;                  
  flex-wrap: wrap;             
  padding: 2rem;
}

.hero-illustration {
  flex: 0 0 400px;             
  background: #ddd;
  border-radius: var(--radius);
  overflow: hidden;
}
.hero-illustration img {
  display: block;
  width: 100%;
  height: auto;
}

.card-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  max-width: 520px;            
}

.card {
  flex: 1 1 calc(50% - 8px);
  min-width: 240px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  text-decoration: none;
  color: inherit;
  box-shadow: 0 1px 0 rgba(0, 0, 0, .03);
  transition: transform 0.2s;
}
.card:hover { transform: translateY(-4px); }

@media (max-width: 768px) {
  .hero-body { flex-direction: column; }
  .hero-illustration { flex: none; width: 100%; }
  .card-grid { max-width: 100%; }
  .card { flex: 1 1 100%; }
}


/* -----------------------------
   7) Section Header / Buttons
----------------------------- */
.section-header{
  display:flex;               
  justify-content:space-between;
  align-items:center;
  gap:var(--gap);
  margin-bottom:14px;
}
.section-title{
  margin:0;
  font-size: clamp(22px, 3vw, 32px);
}
.btn{
  display:inline-block;
  padding:8px 12px;
  border-radius:10px;
  text-decoration:none;
  font-weight:600;
}
.btn--ghost{
  color:var(--ink);
  border:1px solid var(--line);
  background:#f3f4f6;
}

/* -----------------------------
   8) Intro page (two columns)
----------------------------- */
.page-body.two-col{
  display:grid;
  grid-template-columns: 1fr 340px;
  gap: var(--gap);
  background:#fff;
  border:1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(16px, 2.2vw, 24px);
}
.page-body .media-right img{
  width:100%; height:auto; display:block;
  border-radius: 10px;
  background:#ddd;
}
.col--full{ grid-column:1 / -1; }

/* -----------------------------
   9) Key Themes layout
----------------------------- */
.virtue-grid{
  display: grid;
  grid-template-columns: 120px 1fr; 
  gap: var(--gap);
  align-items: stretch;
}

.virtue-kanji{
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f3f4f6;
  border: 1px solid var(--line);
  border-radius: 12px;
  font-weight: 800;
  font-size: clamp(28px, 4.2vw, 40px); 
  letter-spacing: .1em;
  line-height: 1;
  color: var(--ink);
  height: 100%;
}

.virtue-explain{
  background:#fff;
  border:1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(14px, 2vw, 18px);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.virtue-explain h3{
  margin:0 0 4px;
  font-size: clamp(18px, 2.2vw, 22px);
}
.virtue-explain p{
  margin:0;
  color: var(--ink);
}

.theme-rows{ margin-top: var(--gap); }

@media (max-width: 720px){
  .virtue-grid{
    grid-template-columns: 1fr;       
    gap: 12px;
  }
  .virtue-kanji{ height:auto; padding:16px 0; }
}

/* =============================
   The Three kingdoms page
============================= */
.kingdoms-row{
  display: flex;
  align-items: stretch;
  justify-content: center;
  gap: 24px;
  padding: 18px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scroll-snap-type: x mandatory;
}

.kingdom-card{
  scroll-snap-align: start;
  flex: 0 0 clamp(240px, 28vw, 360px); 
  height: clamp(160px, 24vw, 220px);
  border-radius: 18px;
  border: 1px solid var(--line);
  box-shadow: 0 8px 20px rgba(0,0,0,.08), inset 0 1px 0 rgba(255,255,255,.2);
  background: #fff;
  position: relative;
  padding: 18px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  isolation: isolate; 
  transition: transform .18s ease, box-shadow .18s ease, filter .18s ease;
}

.kingdom-cn{
  font-weight: 900;
  font-size: clamp(48px, 6vw, 72px);
  line-height: 1;
  margin-bottom: 6px;
  color: #fff;
  text-shadow: 0 2px 6px rgba(0,0,0,.25);
  letter-spacing: .06em;
}
.kingdom-en{
  font-weight: 800;
  font-size: clamp(18px, 2.2vw, 22px);
  letter-spacing: .18em;
  color: #f8fafc;
  text-shadow: 0 1px 3px rgba(0,0,0,.25);
}

.kingdom-wei{
  background: linear-gradient(135deg, #1e3a8a 0%, #0a246a 100%);
}
.kingdom-shu{
  background: linear-gradient(135deg, #b91c1c 0%, #8a1111 100%);
}
.kingdom-wu{
  background: linear-gradient(135deg, #065f46 0%, #044434 100%);
}

.kingdom-card:hover{
  transform: translateY(-6px);
  box-shadow: 0 14px 28px rgba(0,0,0,.18), 0 0 0 2px rgba(255,255,255,.2) inset;
  filter: saturate(1.1);
}


@media (max-width: 640px){
  .kingdoms-row{
    gap: 16px;
    padding-inline: 12px;
  }
  .kingdom-card{
    display: flex;
    flex-basis: 82vw; 
    height: 46vw;
    color: inherit;
  }
}


/* -----------------------------
   10) Accessibility helpers
----------------------------- */
.visually-hidden{
  position:absolute !important;
  height:1px;width:1px;overflow:hidden;
  clip:rect(1px,1px,1px,1px);
  white-space:nowrap;border:0;padding:0;margin:-1px;
}

/* -----------------------------
   11) Responsive
----------------------------- */
@media (max-width: 980px){
  body{ grid-template-columns: 200px 1fr; }
  .hero-body{ grid-template-columns: 1fr; }
}
@media (max-width: 720px){
  body{ grid-template-columns: 1fr; grid-template-areas:
    "header" "main" "footer"; }
  .site-sidebar{ display:none; }
  .page-body.two-col{ grid-template-columns: 1fr; }
  .theme-rows{ grid-template-columns: 1fr; }
}

/* ===== Sidebar context navigation ===== */
.side-title{
  margin: 0 0 6px;
  font-size: 13px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: .06em;
}
.side-group{
  margin: 8px 0 10px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
  overflow: hidden;
}
.side-group > summary{
  cursor: pointer;
  padding: 10px 12px;
  font-weight: 700;
  list-style: none;
  outline: none;
}
.side-group[open] > summary{ background: #f8fafc; }
.side-group__title::-webkit-details-marker{ display:none; }

.side-list{
  list-style: none;
  margin: 0;
  padding: 6px 10px 10px 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.side-list a{
  display:block;
  padding:8px 10px;
  border-radius:8px;
  text-decoration:none;
  color: var(--ink);
}
.side-list a:hover{ background:#f3f4f6; }
.side-list .is-active > a,
.side-list a[aria-current="page"]{
  background: var(--ink);
  color: #fff;
}

.side-caption{
  display:block;
  margin:8px 0 2px;
  font-weight:700;
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: .06em;
}
.side-sub{
  list-style: none;
  margin: 0 0 6px 10px;
  padding: 0;
  border-left: 2px solid var(--line);
}
.side-sub li a{
  padding:6px 8px;
  border-radius: 8px;
}

/* ===== Page TOC ===== */
.side-toc{
  margin-top: 18px;
  padding-top: 12px;
  border-top: 1px dashed var(--line);
}
.toc-list{
  margin: 6px 0 0;
  padding-left: 18px;
  display: grid;
  gap: 6px;
}
.toc-list a{
  text-decoration:none;
  color: var(--ink);
  border-radius: 8px;
  padding: 4px 4px;
}
.toc-list a:hover{ background:#f3f4f6; }

/* ===== Prose helpers for Introduction content ===== */
.prose h2{
  margin: 18px 0 6px;
  font-size: clamp(18px, 2.2vw, 22px);
}
.prose p{ margin: 0 0 10px; }

@media (max-width: 720px){
  .site-sidebar{ display:none; }
}