.doc-header {
     padding-top: 8.5rem;
     padding-bottom: 2.5rem;
     background-image:
         linear-gradient(rgba(234, 244, 241, 0.9), rgba(234, 244, 241, 0.98)),
         repeating-linear-gradient(0deg, rgba(14, 42, 46, 0.05) 0 1px, transparent 1px 42px),
         repeating-linear-gradient(90deg, rgba(14, 42, 46, 0.05) 0 1px, transparent 1px 42px);
     border-bottom: 1px solid var(--line);
 }

 .eyebrow {
     font-family: 'IBM Plex Mono', monospace;
     font-size: 0.78rem;
     letter-spacing: 0.14em;
     text-transform: uppercase;
     color: var(--copper-deep);
     font-weight: 600;
 }

 .doc-title {
     font-size: clamp(1.9rem, 3vw, 2.6rem);
     font-weight: 700;
     margin-top: 0.5rem;
 }

 .updated-note {
     font-size: 0.85rem;
     color: var(--slate);
     margin-top: 0.6rem;
 }

 /* TOC */
 .toc {
     position: sticky;
     top: 100px;
     background: #fff;
     border: 1px solid var(--line);
     border-radius: 10px;
     padding: 1.2rem 1.3rem;
 }

 .toc .toc-label {
     font-family: 'IBM Plex Mono', monospace;
     font-size: 0.7rem;
     letter-spacing: 0.1em;
     text-transform: uppercase;
     color: var(--slate);
     font-weight: 600;
     margin-bottom: 0.7rem;
     display: block;
 }

 .toc ul {
     list-style: none;
     padding: 0;
     margin: 0;
     display: flex;
     flex-direction: column;
     gap: 0.55rem;
 }

 .toc a {
     font-size: 0.86rem;
     color: var(--ink-soft);
     text-decoration: none;
 }

 .toc a:hover {
     color: var(--teal-deep);
 }

 /* content */
 .doc-body {
     padding: 3.5rem 0 5rem;
 }

 .doc-section {
     padding-top: 1.2rem;
     margin-top: 1.2rem;
     scroll-margin-top: 100px;
     padding-bottom: 2px;
 }

 .doc-section h2 {
     font-size: 1.28rem;
     font-weight: 700;
     display: flex;
     align-items: center;
     gap: 0.6rem;
     margin-bottom: 0.9rem;
 }

 .doc-section h2 .idx {
     font-family: 'IBM Plex Mono', monospace;
     color: var(--amber-deep);
     font-size: 0.9rem;
     font-weight: 700;
 }

 .doc-section p,
 .doc-section li {
     color: var(--ink-soft);
     font-size: 0.96rem;
 }

 .doc-section h3 {
     font-size: 1rem;
     margin-top: 1.2rem;
     margin-bottom: 0.5rem;
     color: var(--ink);
 }

 hr.doc-rule {
     border-color: var(--line);
     margin: 0;
 }

 .identity-card {
     background: #fff;
     border: 1px solid var(--line);
     border-radius: 10px;
     padding: 1.6rem 1.7rem;
     position: relative;
 }

 .identity-card::before,
 .identity-card::after {
     content: "";
     position: absolute;
     width: 14px;
     height: 14px;
     border-color: var(--amber);
     border-style: solid;
 }

 .identity-card::before {
     top: -1px;
     left: -1px;
     border-width: 2px 0 0 2px;
 }

 .identity-card::after {
     bottom: -1px;
     right: -1px;
     border-width: 0 2px 2px 0;
 }

 .identity-row {
     display: flex;
     justify-content: space-between;
     gap: 1rem;
     padding: 0.55rem 0;
     border-bottom: 1px dashed var(--line);
     font-size: 0.92rem;
 }

 .identity-row:last-child {
     border-bottom: none;
 }

 .identity-row .k {
     color: var(--slate);
 }

 .identity-row .v {
     font-family: 'IBM Plex Mono', monospace;
     color: var(--ink);
     text-align: right;
     font-weight: 600;
 }

 .callout {
     background: var(--amber-soft);
     border: 1px solid var(--amber);
     border-radius: 8px;
     padding: 0.9rem 1.1rem;
     font-size: 0.85rem;
     color: #6B4A0E;
     margin-bottom: 2rem;
 }

 .callout strong {
     color: #5A3D0B;
 }