/* A scientific plate; only direct interaction changes the illustrated state. */
.brain-study{--background:#111111;--surface:#1e1e1e;--text:#f5f5f5;--muted:#b3b3b3;--active:#ffffff;--focus:#ffffff;--line:#2c2c2c;--line-strong:#757575;color:var(--text);background:var(--background);--brain-ratio:560/448;--brain-tool-size:40px;--brain-tools-mobile-height:120px}
.brain-viewport{position:relative;aspect-ratio:var(--brain-ratio);width:100%;isolation:isolate;overflow:hidden;background:var(--background);touch-action:pan-y}
.brain-fallback,.brain-canvas{position:absolute;inset:0;width:100%;height:100%}
.brain-fallback{pointer-events:none}
.brain-plate{display:none;width:100%;height:100%;object-fit:contain}
[data-state="0"] .brain-plate-physics,[data-state="1"] .brain-plate-evidence,[data-state="2"] .brain-plate-people{display:block}
.brain-canvas{display:none;touch-action:pan-y;cursor:grab}
.brain-canvas:active{cursor:grabbing}
[data-brain-status="ready"] .brain-canvas{display:block}
[data-brain-status="ready"] .brain-fallback{visibility:hidden}
.brain-annotation{position:absolute;z-index:2;left:var(--brain-label-x,50%);top:var(--brain-label-y,35%);max-width:24ch;padding:var(--space-1);font-size:12px;line-height:1.5;color:var(--text);background:var(--background);pointer-events:none;white-space:nowrap}
.brain-annotation:before{content:"";position:absolute;left:0;top:0;z-index:-1;width:var(--brain-leader-length,0px);height:1px;background:var(--gray-400);transform:rotate(var(--brain-leader-angle,0deg));transform-origin:left center}
.brain-tools-slot{min-height:var(--space-8)}
.brain-tools{display:none;flex-wrap:wrap;gap:var(--space-1);align-items:center;min-height:var(--space-6);padding-block:var(--space-1);border-top:1px solid var(--line)}
[data-brain-status="ready"] .brain-tools{display:flex}
.brain-tools button{appearance:none;min-width:var(--brain-tool-size);min-height:var(--brain-tool-size);padding:var(--space-1);border:0;border-bottom:1px solid transparent;background:none;font-size:12px;color:var(--muted);line-height:1.5}
.brain-tools button:hover,.brain-tools button:focus-visible{color:var(--active);border-bottom-color:var(--active)}
.brain-tools button:nth-last-child(2){margin-left:auto}
.brain-help{font-size:12px;line-height:1.6;color:var(--muted);min-height:var(--space-8);margin:0;padding-block:var(--space-1);max-width:66ch}
.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
@media(max-width:599px){.brain-tools-slot{min-height:var(--brain-tools-mobile-height)}.brain-help{min-height:var(--space-10)}.brain-tools button:nth-last-child(2){margin-left:0}.brain-tools{gap:0}.brain-tools button{min-height:48px}}
@media(prefers-reduced-motion:reduce){.brain-canvas,.brain-tools-slot{display:none!important}.brain-fallback{visibility:visible!important}}
@media print{.brain-canvas,.brain-tools-slot,.brain-annotation,.brain-help{display:none!important}.brain-fallback{visibility:visible!important}.brain-viewport{break-inside:avoid}}

/* The homepage stage is a single product visual, with a readable knowledge layer. */
.hero-brain{width:min(1200px,calc(100% - var(--gutter)*2));margin:var(--space-4) auto 0;border-radius:24px;overflow:hidden}
.hero-brain .brain-viewport{aspect-ratio:2/1}
.hero-brain .brain-tools-slot,.hero-brain .brain-help,.hero-brain>figcaption{padding-inline:var(--space-3)}
.hero-brain .brain-tools-slot{min-height:var(--space-8)}
.hero-brain>figcaption{font-size:12px;line-height:1.6;color:var(--muted);padding-block:var(--space-2);margin:0;max-width:none;border-top:1px solid var(--line)}
.brain-invitation{position:absolute;left:var(--space-3);bottom:var(--space-2);pointer-events:none;color:var(--muted);font-size:12px;line-height:1.5;margin:0}
.brain-knowledge{--background:#ffffff;--text:#1d1d1f;--muted:#616166;--active:#1d1d1f;--focus:#1d1d1f;--line:#dedee2;background:var(--background);color:var(--text);padding:var(--space-4);border-top:1px solid var(--line);min-height:312px}
.brain-topic-heading{display:flex;align-items:center;justify-content:space-between;gap:var(--space-2);margin-bottom:var(--space-2)}
.brain-topic-heading>p{font-size:13px;color:var(--muted);margin:0}
.brain-topic-navigation{display:flex;gap:var(--space-1)}
.brain-topic-navigation button{width:40px;height:40px;padding:var(--space-1);color:var(--text);background:var(--background);border:1px solid var(--line);border-radius:8px;font-size:18px}
.brain-topic-navigation button:hover{background:#f5f5f7}
.brain-knowledge h2{font-size:clamp(24px,2.5vw,36px);line-height:1.15;letter-spacing:-.025em;margin-bottom:var(--space-2);max-width:36ch}
.brain-knowledge>p{font-size:15px;line-height:1.7;max-width:68ch;margin:0 0 var(--space-2)}
.brain-knowledge .brain-topic-formula{font-family:var(--font-heading);font-size:20px;color:var(--text);padding-block:var(--space-1)}
.brain-knowledge .brain-topic-unit,.brain-knowledge .brain-topic-limit,.brain-knowledge .brain-topic-source{font-size:12px;color:var(--muted)}
.brain-knowledge .brain-topic-source{margin-bottom:0}
.principle-study.brain-study{padding:var(--space-2);border-radius:16px;overflow:hidden}
@media(max-width:599px){.hero-brain .brain-viewport{aspect-ratio:1.05}.hero-brain{border-radius:16px}.hero-brain .brain-tools-slot{min-height:var(--brain-tools-mobile-height)}.brain-knowledge{padding:var(--space-3);min-height:408px}.brain-invitation{max-width:24ch}}
@media(min-width:1920px){.hero-brain{width:min(1600px,calc(100% - var(--gutter)*2))}}
@media(min-width:3000px){.hero-brain{width:100%;max-width:3840px;border-radius:0}.hero-brain .brain-viewport{aspect-ratio:16/9}}
@media print{.hero-brain{border-radius:0;width:100%}.brain-knowledge{min-height:0}.brain-topic-navigation,.brain-invitation{display:none!important}}

.brain-activate{display:inline-flex;align-items:center;justify-content:center;min-height:40px;margin-block:var(--space-1);padding:var(--space-1) var(--space-2);border:1px solid var(--line-strong);border-radius:8px;background:none;color:var(--text);font-size:13px;line-height:1.5}
.brain-activate:hover{border-color:var(--active)}
.brain-activate:disabled{color:var(--muted);cursor:progress}
[data-brain-status="ready"] .brain-activate,[data-brain-status="fallback"] .brain-activate{display:none}
@media(prefers-reduced-motion:reduce){.brain-activate{display:none!important}}

/* Native modal inspection preserves one canvas and its keyboard controls. */
.network-dialog{max-width:none;max-height:none;width:100vw;height:100svh;padding:0;margin:0;border:0;background:#111111;color:#f5f5f5;overflow:hidden}
.network-dialog::backdrop{background:#111111}
.network-dialog .principle-study{position:relative;width:100%;height:100%;padding:0;border-radius:0}
.network-dialog .brain-viewport{width:100%;height:100%;aspect-ratio:auto}
.network-dialog .brain-tools-slot{position:absolute;z-index:3;bottom:var(--space-3);left:var(--space-3);right:var(--space-3);min-height:0;background:#111111}
.network-dialog .brain-tools{flex-wrap:wrap;border-top:1px solid var(--line);padding-inline:var(--space-2)}
.network-dialog .brain-help{display:none}
.network-dialog figcaption{position:absolute;left:var(--space-3);top:var(--space-3);max-width:60ch;border:0;padding:0 var(--space-2);background:#111111}
.network-close{position:absolute;z-index:4;top:var(--space-3);right:var(--space-3);min-height:48px;padding:var(--space-1) var(--space-2);color:#f5f5f5;border:1px solid #757575;border-radius:8px;background:#111111;font-size:14px}
@media(max-width:599px){.network-dialog figcaption{right:var(--space-3);top:var(--space-10);font-size:12px}.network-dialog .brain-tools-slot{bottom:var(--space-2);left:var(--space-2);right:var(--space-2)}}