.section-nav{position:fixed;z-index:60;top:calc(var(--header-h) + 14px);left:50%;transform:translateX(-50%) translateY(-8px);display:flex;align-items:center;gap:2px;padding:5px;border-radius:100px;background:rgba(24,24,26,0.88);border:1px solid rgba(255,255,255,0.12);-webkit-backdrop-filter:blur(18px) saturate(160%);backdrop-filter:blur(18px) saturate(160%);box-shadow:0 18px 40px -22px rgba(0,0,0,0.7);opacity:0;visibility:hidden;transition:opacity 400ms var(--ease),transform 400ms var(--ease),visibility 400ms}.section-nav.is-visible{opacity:1;visibility:visible;transform:translateX(-50%) translateY(0)}.section-nav a{padding:8px 16px;border-radius:100px;font-family:'Hanken Grotesk',sans-serif;font-weight:700;font-size:12.5px;letter-spacing:0.03em;color:rgba(255,255,255,0.78);text-decoration:none;white-space:nowrap;transition:color 240ms var(--ease),background 240ms var(--ease)}.section-nav a:hover{color:#fff}.section-nav a:focus-visible{outline:2px solid var(--tsa-orange);outline-offset:3px}.section-nav a.is-active{color:var(--ink);background:#fff}.section-nav__trigger{display:none}@media (max-width:1024px){.section-nav{top:calc(var(--header-h) + 12px);left:auto;right:clamp(12px,4vw,20px);width:auto;max-width:min(92vw,420px);transform:translateY(-8px);display:block;gap:0;padding:4px;border-radius:999px;background:rgba(20,20,24,0.55);-webkit-backdrop-filter:blur(28px) saturate(185%);backdrop-filter:blur(28px) saturate(185%);border:1px solid rgba(255,255,255,0.16);box-shadow:0 24px 54px -20px rgba(0,0,0,0.62),inset 0 1px 0 rgba(255,255,255,0.09);overflow:hidden;transition:opacity 420ms var(--ease),transform 520ms cubic-bezier(.22,1,.36,1),border-radius 380ms var(--ease),visibility 420ms}.section-nav.is-visible{transform:translateY(0)}.section-nav.is-open{border-radius:24px;padding:5px;max-height:calc(100dvh - var(--header-h) - 28px);overflow-y:auto;-webkit-overflow-scrolling:touch}.section-nav__trigger{display:flex;align-items:center;justify-content:center;gap:9px;width:100%;min-height:42px;padding:9px 20px;background:transparent;border:0;cursor:pointer;color:#fff;border-radius:999px;font-family:'Hanken Grotesk',sans-serif;font-weight:700;font-size:13px;letter-spacing:0.02em}.section-nav.is-open .section-nav__trigger{justify-content:space-between;padding:10px 16px 8px}.section-nav__trigger-label{white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.section-nav__caret{width:8px;height:8px;flex:none;margin-top:-3px;border-right:2px solid var(--tsa-orange);border-bottom:2px solid var(--tsa-orange);transform:rotate(45deg);transition:transform .4s cubic-bezier(.22,1,.36,1),margin-top .4s var(--ease)}.section-nav.is-open .section-nav__caret{transform:rotate(-135deg);margin-top:3px}.section-nav a{display:none;margin:2px 3px;padding:11px 16px;border-radius:13px;color:rgba(255,255,255,0.82);text-decoration:none;font-weight:700;font-size:13.5px;letter-spacing:0.01em;min-height:44px;align-items:center;transition:background .2s var(--ease),color .2s var(--ease)}.section-nav.is-open a{display:flex}.section-nav a.is-active{background:rgba(255,255,255,0.15);color:#fff}}@media (prefers-reduced-motion:reduce){.section-nav,.section-nav a{transition:none !important}}[data-chapter-target]{scroll-margin-top:calc(var(--header-h) + 70px)}