/* Empty slots inherit the surrounding page surface in either theme. */
body { --ad-placeholder-bg: var(--bg-color, #fafafa); }
body.interactive-course { --ad-placeholder-bg: var(--lesson-surface); }
body.how-to { --ad-placeholder-bg: var(--ht-bg); }
.desktop-side-ad { --ad-placeholder-bg: var(--bg, var(--ht-bg, var(--bg-color, #fafafa))); }
:is(.lesson-top-ad, .how-to-top-ad, .desktop-side-ad),
ins.adsbygoogle { background-color: var(--ad-placeholder-bg); }
ins.adsbygoogle iframe { background-color: transparent; color-scheme: inherit; }
/* An unfilled slot has no creative to show; keep its reserved themed space. */
ins.adsbygoogle[data-ad-status='unfilled'] iframe { visibility: hidden; }