:root{
  --c1:#213448; /* primary */
  --c2:#547792; /* secondary */
  --c3:#94B4C1; /* accent */
  --c4:#ECEFCA; /* background */
  --radius:16px;
  --shadow: 0 10px 30px rgba(0,0,0,.10);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  background: var(--c4);
  color: var(--c1);
  line-height:1.55;
}

a{color: var(--c2); text-decoration:none}
a:hover{text-decoration:underline}

.header{
  position:sticky; top:0; z-index:50;
  backdrop-filter: blur(10px);
  background: color-mix(in srgb, var(--c4) 78%, white 22%);
  border-bottom: 1px solid color-mix(in srgb, var(--c3) 40%, transparent 60%);
}

.header-inner{
  max-width:1200px; margin:0 auto;
  padding: 14px 16px;
  display:flex; align-items:center; justify-content:space-between; gap:12px;
}

.brand{
  display:flex; flex-direction:column;
  gap:2px;
}
.brand .title{font-weight:800; letter-spacing:.2px}
.brand .meta{font-size: 13px; color: color-mix(in srgb, var(--c1) 70%, var(--c2) 30%)}

.toc-toggle{
  display:none;
  border:1px solid color-mix(in srgb, var(--c3) 60%, transparent 40%);
  background: white;
  color: var(--c1);
  padding:10px 12px;
  border-radius: 12px;
  box-shadow: 0 6px 18px rgba(0,0,0,.06);
  cursor:pointer;
}

.layout{
  max-width:1200px; margin:0 auto;
  padding: 18px 16px 80px;
  display:grid;
  grid-template-columns: 320px 1fr;
  gap: 18px;
}

.sidebar{
  position: sticky;
  top: 72px;
  align-self:start;
}

.card{
  background:white;
  border: 1px solid color-mix(in srgb, var(--c3) 55%, transparent 45%);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow:hidden;
}

.toc{
  padding: 14px 14px 10px;
  max-height: calc(100vh - 110px);
  overflow:auto;
}

.toc h2{
  margin:0 0 8px;
  font-size: 14px;
  letter-spacing:.08em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--c1) 70%, var(--c2) 30%);
}
.toc ul{list-style:none; padding-left:0; margin:0}
.toc li{margin: 6px 0}
.toc a{
  display:block;
  padding: 7px 10px;
  border-radius: 12px;
  color: var(--c1);
}
.toc a:hover{
  background: color-mix(in srgb, var(--c3) 26%, white 74%);
  text-decoration:none;
}
.toc a.active{
  background: color-mix(in srgb, var(--c2) 18%, white 82%);
  border: 1px solid color-mix(in srgb, var(--c2) 35%, transparent 65%);
}

.toc ul ul{
  padding-left: 12px;
  border-left: 2px solid color-mix(in srgb, var(--c3) 45%, transparent 55%);
  margin-left: 8px;
}

.main{
  padding: 18px 18px 6px;
}

.hero{
  padding: 18px 18px 16px;
  border-bottom: 1px solid color-mix(in srgb, var(--c3) 55%, transparent 45%);
  background: linear-gradient(135deg,
    color-mix(in srgb, var(--c3) 22%, white 78%),
    white
  );
}
.hero h1{
  margin:0;
  font-size: 28px;
  line-height: 1.15;
}
.hero .sub{
  margin-top:10px;
  color: color-mix(in srgb, var(--c1) 75%, var(--c2) 25%);
  font-size: 14px;
}
.badge-row{display:flex; flex-wrap:wrap; gap:8px; margin-top:12px}
.badge{
  padding: 6px 10px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--c2) 12%, white 88%);
  border: 1px solid color-mix(in srgb, var(--c2) 28%, transparent 72%);
  font-size: 12px;
}

.content{
  padding: 6px 0 0;
}
.content h2, .content h3{
  scroll-margin-top: 90px;
}
.content h2{
  margin: 22px 0 10px;
  font-size: 22px;
  border-top: 1px solid color-mix(in srgb, var(--c3) 55%, transparent 45%);
  padding-top: 18px;
}
.content h3{
  margin: 18px 0 8px;
  font-size: 18px;
  color: color-mix(in srgb, var(--c1) 85%, var(--c2) 15%);
}
.content p{margin: 10px 0}
.content ol, .content ul{
  margin: 10px 0 10px 20px;
}
.content li{margin: 7px 0}
.figure{
  margin: 14px 0;
  background: color-mix(in srgb, var(--c4) 55%, white 45%);
  border: 1px solid color-mix(in srgb, var(--c3) 55%, transparent 45%);
  border-radius: 14px;
  padding: 10px;
}
.figure img{
  width:100%;
  height:auto;
  display:block;
  border-radius: 10px;
  box-shadow: 0 10px 24px rgba(0,0,0,.10);
  cursor: zoom-in;
}
.figure figcaption{
  margin-top: 8px;
  font-size: 12px;
  color: color-mix(in srgb, var(--c1) 65%, var(--c2) 35%);
}

.footer{
  margin-top: 16px;
  padding: 14px 18px;
  border-top: 1px solid color-mix(in srgb, var(--c3) 55%, transparent 45%);
  color: color-mix(in srgb, var(--c1) 70%, var(--c2) 30%);
  font-size: 13px;
}

/* Lightbox */
.lightbox{
  position: fixed; inset:0;
  background: rgba(0,0,0,.78);
  display:none;
  align-items:center; justify-content:center;
  padding: 16px;
  z-index: 999;
}
.lightbox.open{display:flex}
.lightbox img{
  max-width: min(1100px, 96vw);
  max-height: 90vh;
  border-radius: 14px;
  box-shadow: 0 20px 50px rgba(0,0,0,.35);
  cursor: zoom-out;
}

@media (max-width: 980px){
  .layout{grid-template-columns: 1fr}
  .sidebar{position: static}
  .toc-toggle{display:inline-flex; align-items:center; gap:8px}
  .toc-card{display:none}
  .toc-card.open{display:block}
}