:root{
  --bg: rgb(245,248,252);
  --card: rgb(255,255,255);
  --text: rgb(20,22,25);
  --muted: rgb(90,98,110);
  --accent: rgb(30,64,175);         /* deep professional blue (borders) */
  --accent-2: rgb(16,185,129);      /* teal accent for highlights */
  --border: rgba(30,64,175,0.22);   /* subtle border */
  --shadow: 0 10px 20px rgba(0,0,0,0.06);
}

*{ box-sizing: border-box; }
html, body{ height:100%; }
body{
  margin:0;
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Arial, "Noto Sans", sans-serif;
  font-weight: 700; /* All fonts bold per requirement */
  line-height: 1.45;
}

/* Layout */
.sidebar{
  position: fixed;
  inset: 0 auto 0 0;
  width: 290px;
  background: linear-gradient(180deg, rgba(30,64,175,0.10), rgba(30,64,175,0.04));
  border-right: 3px solid var(--accent);
  padding: 14px 12px;
  overflow-y: auto;
}
.sidebar-header{
  display: flex; align-items: center; gap: 10px; margin-bottom: 12px;
}
#menuToggle{
  border: 2px solid var(--accent);
  border-radius: 10px;
  padding: 6px 10px;
  background: var(--card);
  cursor: pointer;
}
.brand{ color: var(--accent); letter-spacing: 0.4px; }

.toc{ display: grid; gap: 8px; margin-top: 10px; }
.toc-link{
  text-align: left;
  background: var(--card);
  color: var(--text);
  border: 2px solid var(--accent);
  border-radius: 12px;
  padding: 10px 12px;
  cursor: pointer;
  box-shadow: var(--shadow);
}
.toc-link:hover{ outline: 3px solid rgba(30,64,175,0.15); }

.print-wrap{ margin-top: 16px; }
.print-btn{
  width: 100%;
  padding: 10px 12px;
  border-radius: 12px;
  border: 2px solid var(--accent);
  background: var(--accent);
  color: white;
  cursor: pointer;
}

.content{
  margin-left: 310px;
  padding: 24px;
  max-width: 1100px;
}

.card{
  background: var(--card);
  border: 2px solid var(--border);
  border-left: 6px solid var(--accent);
  border-radius: 18px;
  padding: 18px 18px 14px 18px;
  margin: 16px 0;
  box-shadow: var(--shadow);
}

h1{
  margin: 8px 0 12px 0;
  color: var(--accent);
  font-size: 1.6rem;
}
h2{
  margin: 12px 0 8px 0;
  color: var(--muted);
  font-size: 1.2rem;
}

.bullets { padding-left: 18px; }
.bullets > li{ margin: 8px 0; }
.bullets ul{ padding-left: 18px; }

.table-wrap{ overflow-x:auto; }
.compare-table{
  width:100%;
  border-collapse: collapse;
  border: 2px solid var(--accent);
}
.compare-table th, .compare-table td{
  padding: 10px 12px;
  border: 1px solid var(--border);
}
.compare-table thead th{
  background: rgba(30,64,175,0.10);
}

.qa{
  margin-top: 12px;
  border: 2px dashed var(--accent);
  border-radius: 14px;
  padding: 8px 12px;
  background: rgba(16,185,129,0.06);
}
.qa summary{ cursor: pointer; }
.qa-body{ margin-top: 8px; }

.diagram-wrap{
  background: linear-gradient(180deg, rgba(16,185,129,0.06), rgba(30,64,175,0.06));
  border: 2px solid var(--accent);
  border-radius: 18px;
  padding: 10px;
  overflow: auto;
}
.diagram{ width:100%; height:auto; display:block; }
.node{
  fill: #fff; stroke: var(--accent); stroke-width: 3;
}
.node-circle{
  fill:#fff; stroke: var(--accent-2); stroke-width: 5;
}
.accent{ fill: rgba(16,185,129,0.12); }
.node-text{
  dominant-baseline: middle; text-anchor: middle; font-family: inherit; font-weight: 700; font-size: 14px; fill: #111;
}
.node-text.center{ font-size: 18px; }

.arrow{
  stroke: var(--accent);
  stroke-width: 3;
  fill: none;
}
.arrow-head{
  fill: var(--accent);
}

.explain{ color:#111; }

.qa-list{ padding-left: 18px; }
.qa-list > li{ margin: 8px 0; }
.qa-list details summary{ cursor: pointer; }

/* Responsive */
@media (max-width: 980px){
  .sidebar{ width: 260px; transform: translateX(-102%); transition: transform 0.25s ease; }
  .sidebar.open{ transform: translateX(0%); }
  .content{ margin-left: 0; padding-top: 64px; }
  .card{ margin: 14px 4px; }
}

/* Print */
@media print {
  .sidebar, #menuToggle, .print-btn { display: none !important; }
  .content { margin: 0; }
  .card { page-break-inside: avoid; border-color: #000; }
  body { background: #fff; color: #000; font-weight: 700; }
}