/* Natural scrolling: sections follow their content, without snapping or scroll capture. */
html:has(.reading-progress){scroll-padding-block-start:24px;scroll-snap-type:none}
[data-chapter]{scroll-margin-block-start:16px}
[data-chapter]:focus{outline:none}
.reading-progress{position:fixed;inset:0 0 auto;z-index:25;display:block;width:100%;height:3px;border:0;appearance:none;pointer-events:none;background:transparent;color:#304fdd}
.reading-progress::-webkit-progress-bar{background:transparent}
.reading-progress::-webkit-progress-value{background:#304fdd}
.reading-progress::-moz-progress-bar{background:#304fdd}

/* Full-width colour changes retain the same content alignment and natural section height. */
.chapter-dark{position:relative;isolation:isolate;--band-bg:#172b34;--band-text:#ced9d9;--band-accent:#e6f48e;color:#fffef8}
.chapter-dark::before{content:'';position:absolute;inset:0;z-index:-1;background:var(--band-bg);box-shadow:0 0 0 100vmax var(--band-bg);clip-path:inset(0 -100vmax);pointer-events:none}
.chapter-dark>.section-heading h2{color:#fffef8}
.chapter-dark>.section-heading h2 em{color:var(--band-accent)}
.chapter-dark>.section-heading p,.chapter-dark>.scope-note{color:var(--band-text)}
.chapter-dark>.section-heading .eyebrow{color:var(--band-accent)}
.chapter-dark>.section-heading .button.secondary{color:#fffef8;border-color:#91aea2;background:transparent}
.chapter-dark>.section-heading .button.secondary:hover{color:var(--band-bg);background:var(--band-accent);border-color:var(--band-accent)}
.chapter-dark a:focus-visible,.chapter-dark button:focus-visible{outline-color:#e6f48e}

/* Keep the mobile concepts in their original colours; only their surrounding story changes tone. */
.chapter-dark .pvl-intro>p,.chapter-dark .pvl-copy>p,.chapter-dark .pvl-image-note{color:var(--band-text)}
.chapter-dark .pvl-concept-label{color:#dbe4e2}
.chapter-dark .pvl-concept-label i{background:var(--band-accent)}
.chapter-dark .pvl-stage-label>span:first-child{color:var(--band-accent)}
.chapter-dark .pvl-stage-label i{background:#597078}
.chapter-dark .pvl-copy h3{color:#fffef8}
.chapter-dark .pvl-copy>a{color:var(--band-accent);border-color:#7f966e}
.chapter-dark .pvl-copy>a:hover{color:#fffef8;border-color:#fffef8}
.chapter-dark .pvl-summary{border-color:#526a70;background:#ffffff06}
.chapter-dark .pvl-summary p{color:var(--band-text)}
.chapter-dark .pvl-summary strong{color:#fffef8}
.chapter-dark .pvl-summary a{color:var(--band-accent)}

@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto!important}}
@media print{.reading-progress{display:none!important}.chapter-dark{print-color-adjust:exact;-webkit-print-color-adjust:exact}}