.bk-root{scroll-margin-top:6rem}.bk-xfade{--bk-radius: 14px;display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);border:1px solid var(--color-border-strong);border-radius:var(--bk-radius);overflow:hidden;background:var(--color-bg);box-shadow:0 1px 2px #0000000a,0 18px 40px -18px #0000002e}.bk-side{position:relative;display:flex;flex-direction:column;gap:.75rem;min-width:0;min-height:15rem;padding:2rem 1.75rem 1.75rem;background:var(--color-bg);border:0;color:var(--color-text);font:inherit;cursor:pointer;transition:background-color .25s ease,opacity .4s ease}.bk-side:before{content:"";position:absolute;top:0;left:0;right:0;height:4px;background:var(--color-accent-fill);transform:scaleX(0);transition:transform .35s cubic-bezier(.22,.61,.36,1)}.bk-side-l{align-items:flex-start;text-align:left}.bk-side-l:before{transform-origin:left}.bk-side-r{align-items:flex-end;text-align:right;border-left:1px solid var(--color-border)}.bk-side-r:before{transform-origin:right}.bk-side:focus-visible{outline:2px solid var(--color-text);outline-offset:-4px}.bk-ch{display:inline-flex;align-items:center;padding:.3rem .65rem;border:1px solid var(--color-border-strong);border-radius:999px;font-size:10px;font-weight:700;letter-spacing:.18em;text-transform:uppercase;color:var(--color-text-muted);transition:background-color .25s ease,border-color .25s ease,color .25s ease}.bk-label{margin-top:auto;font-size:clamp(1.6rem,4.6vw,3.25rem);font-weight:700;line-height:.95;letter-spacing:-.01em;text-transform:uppercase}.bk-foot{display:flex;align-items:flex-end;justify-content:space-between;gap:1rem;width:100%}.bk-side-r .bk-foot{flex-direction:row-reverse}.bk-sub{max-width:24ch;font-size:13px;line-height:1.45;color:var(--color-text-muted)}.bk-go{flex-shrink:0;display:grid;place-items:center;width:2.5rem;height:2.5rem;border-radius:50%;border:1px solid var(--color-border-strong);color:var(--color-text);transition:background-color .25s ease,border-color .25s ease,transform .35s cubic-bezier(.34,1.56,.64,1)}.bk-go svg{width:16px;height:16px}@media(hover:hover){.bk-xfade:not(.is-book):not(.is-question) .bk-side:hover{background:var(--color-bg-subtle)}.bk-xfade:not(.is-book):not(.is-question) .bk-side:hover:before{transform:scaleX(1)}.bk-xfade:not(.is-book):not(.is-question) .bk-side:hover .bk-ch{background:var(--color-text);border-color:var(--color-text);color:var(--color-bg)}.bk-xfade:not(.is-book):not(.is-question) .bk-side:hover .bk-go{background:var(--color-accent-fill);border-color:var(--color-accent-fill);transform:translate(3px)}.bk-xfade:not(.is-book):not(.is-question) .bk-side-l:hover .bk-go{transform:translate(-3px)}}.bk-xfade.is-book .bk-side-l,.bk-xfade.is-question .bk-side-r{background:var(--color-bg-subtle)}.bk-xfade.is-book .bk-side-l:before,.bk-xfade.is-question .bk-side-r:before{transform:scaleX(1)}.bk-xfade.is-book .bk-side-l .bk-ch,.bk-xfade.is-question .bk-side-r .bk-ch{background:var(--color-text);border-color:var(--color-text);color:var(--color-bg)}.bk-xfade.is-book .bk-side-l .bk-go,.bk-xfade.is-question .bk-side-r .bk-go{background:var(--color-accent-fill);border-color:var(--color-accent-fill)}.bk-track{grid-column:1 / -1;display:flex;align-items:center;gap:1rem;height:4.5rem;padding:0 1.25rem;border-top:1px solid var(--color-border);background:var(--color-bg-subtle);box-shadow:inset 0 1px 2px #0000000d;cursor:pointer}.bk-end{display:grid;place-items:center;width:1.6rem;height:1.6rem;border-radius:50%;border:1px solid var(--color-border-strong);font-size:11px;font-weight:700;color:var(--color-text-muted);font-variant-numeric:tabular-nums;transition:background-color .3s ease,border-color .3s ease,color .3s ease}.bk-rail{position:relative;flex:1;height:6px;margin:0 1.75rem;border-radius:3px;background:#dcdcd7;box-shadow:inset 0 1px 2px #00000040}.bk-rail:before{content:"";position:absolute;left:0;right:0;top:-24px;height:8px;background:repeating-linear-gradient(to right,var(--color-border-strong) 0 1px,transparent 1px 10%);border-right:1px solid var(--color-border-strong)}.bk-rail:after{content:"";position:absolute;left:50%;top:-28px;width:1px;height:12px;background:var(--color-text-faint)}.bk-knob{position:absolute;top:50%;left:50%;width:48px;height:30px;transform:translate(-50%,-50%);z-index:1;background:linear-gradient(180deg,#2a2a2a,#0a0a0a);border-radius:3px;box-shadow:0 2px 4px #0000004d,inset 0 1px #ffffff26;transition:left .55s cubic-bezier(.34,1.56,.64,1)}.bk-knob:after{content:"";position:absolute;left:50%;top:4px;bottom:4px;width:2px;transform:translate(-50%);background:#5a5a5a;transition:background .2s ease}.bk-xfade:has(.bk-side:hover) .bk-knob:after,.bk-xfade.is-book .bk-knob:after,.bk-xfade.is-question .bk-knob:after{background:var(--color-accent-fill)}@media(hover:hover){.bk-xfade:not(.is-book):not(.is-question):has(.bk-side-l:hover) .bk-knob{left:38%}.bk-xfade:not(.is-book):not(.is-question):has(.bk-side-r:hover) .bk-knob{left:62%}}.bk-xfade.is-book .bk-knob{left:0%}.bk-xfade.is-question .bk-knob{left:100%}.bk-xfade.is-book .bk-side-r,.bk-xfade.is-question .bk-side-l{opacity:.35}.bk-xfade.is-book .bk-end:first-child,.bk-xfade.is-question .bk-end:last-child{background:var(--color-text);border-color:var(--color-text);color:var(--color-bg)}.bk-xfade.is-book,.bk-xfade.is-question{pointer-events:none}.bk-back-row{padding:0 1.5rem}@media(min-width:640px){.bk-back-row{padding:0 2rem}}@media(min-width:1024px){.bk-back-row{padding:0 2.5rem}}.bk-back{display:inline-flex;align-items:center;gap:.5rem;padding:.25rem 0;background:none;border:0;font:inherit;font-size:11px;font-weight:700;letter-spacing:.2em;text-transform:uppercase;color:var(--color-text-faint);cursor:pointer;transition:color .2s ease}.bk-back:hover{color:var(--color-accent)}.bk-back:focus-visible{outline:2px solid var(--color-accent);outline-offset:3px}@media(max-width:520px){.bk-side{min-height:13rem;padding:1.25rem 1rem;gap:.6rem}.bk-sub{font-size:12px}.bk-foot{flex-direction:column;align-items:flex-start;gap:.75rem}.bk-side-r .bk-foot{flex-direction:column;align-items:flex-end}.bk-go{width:2.1rem;height:2.1rem}.bk-track{padding:0 .75rem;gap:.5rem}.bk-rail{margin:0 1.5rem}.bk-knob{width:42px;height:28px}}