/* Densha de Go! Plug & Play — architecture report styles */
:root {
  --bg: #0f1216;
  --surface: #161b22;
  --surface2: #1c2330;
  --border: #2a3441;
  --fg: #d7dde6;
  --muted: #8b98a8;
  --accent: #4fc3f7;      /* Yamanote cyan-green */
  --accent2: #9ccc65;     /* Yamanote green */
  --warn: #ffb74d;
  --err: #ef5350;
  --code-bg: #10151c;
  --mono: "JetBrains Mono", "Fira Code", ui-monospace, "Cascadia Mono", Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", sans-serif;
  --sidebar-w: 300px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font-family: var(--sans); font-size: 16px; line-height: 1.65;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Layout */
.layout { display: flex; min-height: 100vh; }
nav.sidebar {
  width: var(--sidebar-w); flex: 0 0 var(--sidebar-w);
  background: var(--surface); border-right: 1px solid var(--border);
  position: sticky; top: 0; height: 100vh; overflow-y: auto;
  padding: 20px 14px 40px;
}
nav.sidebar .brand {
  display: block; font-weight: 700; font-size: 15px; color: var(--fg);
  padding: 6px 10px 2px; letter-spacing: .02em;
}
nav.sidebar .brand small { display:block; color: var(--muted); font-weight: 400; font-size: 12px; }
nav.sidebar .brand:hover { text-decoration: none; }
nav.sidebar .brand .go { color: var(--accent2); }
nav.sidebar hr { border: none; border-top: 1px solid var(--border); margin: 12px 8px; }
nav.sidebar .grp {
  font-size: 11px; text-transform: uppercase; letter-spacing: .12em;
  color: var(--muted); padding: 10px 10px 4px;
}
nav.sidebar a.item {
  display: block; padding: 5px 10px; border-radius: 6px;
  color: var(--fg); font-size: 13.5px; line-height: 1.4;
}
nav.sidebar a.item:hover { background: var(--surface2); text-decoration: none; }
nav.sidebar a.item.active { background: var(--surface2); color: var(--accent); border-left: 2px solid var(--accent); padding-left: 8px; }
nav.sidebar a.item .num { color: var(--muted); display: inline-block; width: 22px; }

main.content { flex: 1; min-width: 0; padding: 34px 48px 120px; max-width: 1080px; }
.pagehead { border-bottom: 1px solid var(--border); margin-bottom: 26px; padding-bottom: 18px; }
.pagehead .kicker { color: var(--accent2); font-size: 13px; letter-spacing: .14em; text-transform: uppercase; }
.pagehead h1 { margin: 6px 0 8px; font-size: 32px; line-height: 1.2; }
.pagehead .lede { color: var(--muted); font-size: 16.5px; max-width: 46em; }

h2 { font-size: 24px; margin: 44px 0 12px; padding-top: 10px; border-top: 1px solid var(--border); }
h2 .secno { color: var(--muted); font-weight: 400; margin-right: 10px; font-size: 19px; }
h3 { font-size: 18.5px; margin: 30px 0 8px; color: var(--fg); }
h4 { font-size: 15.5px; margin: 22px 0 6px; color: var(--accent); }
p { margin: 10px 0; max-width: 46em; }
ul, ol { max-width: 46em; }
li { margin: 4px 0; }
strong { color: #fff; }
em { color: var(--fg); }

/* Code */
pre {
  background: var(--code-bg); border: 1px solid var(--border); border-radius: 8px;
  padding: 14px 16px; overflow-x: auto; font-family: var(--mono); font-size: 12.8px;
  line-height: 1.5; color: #cfe3d4; margin: 14px 0;
}
pre .cmt { color: #7d8ca0; font-style: italic; }
pre .k { color: #82aaff; }
pre .fn { color: #e2b96f; }
pre .num { color: #c792ea; }
pre .str { color: #a5d6a7; }
code {
  font-family: var(--mono); font-size: .92em; background: var(--code-bg);
  border: 1px solid var(--border); border-radius: 4px; padding: 1px 5px; color: #cfe3d4;
}
pre code { border: none; background: none; padding: 0; }
.codecap {
  font-size: 12px; color: var(--muted); margin: -8px 0 16px; padding-left: 4px;
}
.codecap b { color: var(--accent); }

/* Tables */
table.tbl {
  border-collapse: collapse; width: 100%; margin: 14px 0; font-size: 13.8px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px; overflow: hidden;
}
table.tbl th {
  background: var(--surface2); color: var(--fg); text-align: left;
  padding: 8px 12px; border-bottom: 1px solid var(--border); font-weight: 600; white-space: nowrap;
}
table.tbl td { padding: 7px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
table.tbl tr:last-child td { border-bottom: none; }
table.tbl td.mono, table.tbl th.mono { font-family: var(--mono); font-size: 12.5px; color: #cfe3d4; }
table.tbl td.c { text-align: center; }
table.tbl .ok { color: var(--accent2); }
table.tbl .warn { color: var(--warn); }
table.tbl .err { color: var(--err); }

/* Callouts */
.note, .warn, .tip {
  border-left: 3px solid var(--accent); background: var(--surface);
  padding: 10px 16px; margin: 16px 0; border-radius: 0 8px 8px 0; font-size: 14.5px; max-width: 50em;
}
.warn { border-left-color: var(--warn); }
.tip { border-left-color: var(--accent2); }
.note .t, .warn .t, .tip .t { font-weight: 700; font-size: 12px; letter-spacing: .1em; text-transform: uppercase; display: block; margin-bottom: 4px; color: var(--muted); }
.warn .t { color: var(--warn); }
.tip .t { color: var(--accent2); }

/* Figures */
figure { margin: 22px 0; text-align: center; }
figure img, figure svg {
  max-width: 100%; border: 1px solid var(--border); border-radius: 8px;
  background: #000; display: block; margin: 0 auto;
}
figure.diagram img, figure.diagram svg { background: transparent; border: none; }
figcaption { color: var(--muted); font-size: 13px; margin-top: 8px; max-width: 52em; display: inline-block; text-align: left; }
.imgrow { display: flex; gap: 14px; flex-wrap: wrap; justify-content: center; }
.imgrow figure { flex: 1 1 320px; max-width: 480px; }

/* TOC cards on index */
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; margin: 20px 0; }
.card {
  display: block; background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 16px 18px; color: var(--fg);
}
.card:hover { border-color: var(--accent); text-decoration: none; }
.card .cn { color: var(--accent2); font-size: 12px; letter-spacing: .1em; text-transform: uppercase; }
.card .ct { font-weight: 700; font-size: 16px; margin: 4px 0 6px; }
.card .cd { color: var(--muted); font-size: 13px; line-height: 1.5; }

/* Footer pager */
.pager { display: flex; justify-content: space-between; margin-top: 60px; padding-top: 18px; border-top: 1px solid var(--border); }
.pager a { font-size: 14px; }
.pager .next { color: var(--accent); }

/* small helpers */
.small { font-size: 13px; color: var(--muted); }
.center { text-align: center; }
.katex, .math { font-family: var(--mono); }
hr.sep { border: none; border-top: 1px dashed var(--border); margin: 30px 0; }

@media (max-width: 1100px) {
  nav.sidebar { display: none; }
  main.content { padding: 24px 20px 80px; }
}