Enabling `toc.sticky` while setting `globaltoc_collapse` to `True` leads to overlapping / disappearing items in global TOC / left sidebar

[ani-per]

The conditional section of index.ts when toc.sticky is enabled, which was added 3 years ago, seems to be out of date with the latest codebase.

sphinx-immaterial/src/templates/assets/javascripts/components/toc/index.ts

Lines 382 to 422 in 12adf37

	/* sphinx-immaterial: sticky toc headings */
	if (feature("toc.sticky")) {
	watchElementSize(document.body).pipe(distinctUntilKeyChanged("width"),
	debounceTime(0)).subscribe(() => {
	// The `position: sticky` CSS feature by itself is
	// sufficient to enable a single level of "sticky" headings.
	// To display multiple levels of sticky headings, it is
	// necessary to specify a `top` position for each nested
	// heading that is exactly the sum of the heights of the
	// ancestor headings. For fixed-height headings that can be
	// done statically, but this theme wraps long titles.
	// Therefore, we must use JavaScript to compute the
	// necessary top positions for each heading.
	const existingHeights = new Map<HTMLElement, {height: string, zindex: number}>()
	const heightProperty = "--md-nav__header-height"
	for (const link of getElements(".md-nav__link", el)) {
	const nav = link.nextElementSibling
	if (!(nav instanceof HTMLElement) || nav.tagName !== "NAV") {
	continue
	}
	let heightStr = ""
	let zindex = NaN
	const parentNav = nav.parentElement!.closest("nav")
	if (parentNav !== null) {
	const info = existingHeights.get(parentNav)
	if (info !== undefined) {
	heightStr = `${info.height} + `
	zindex = info.zindex - 1
	}
	}
	if (isNaN(zindex)) {
	zindex = 100
	}
	heightStr += `${link.offsetHeight}px + 0.625em`
	link.classList.add("md-nav__sticky")
	link.style.setProperty("--md-nav__sticky-zindex", zindex.toString())
	nav.style.setProperty(heightProperty, `calc(${heightStr})`)
	existingHeights.set(nav, {height: heightStr, zindex})
	}
	})
	}

See the following example when toc.sticky and globaltoc_collapse are enabled - the TOC headers obscure their first child entirely (see "Officers" heading) and overlap the next header (see "Sets" heading):

Inspecting the TOC headers ("Officers", "Sets") and disabling the --md-nav__sticky-zindex and --md-nav__header-height properties set by lines 417 and 418 fixes the issue, even when scrolling:

Hence I'm guessing that removing lines 417 and 418 would be enough to fix this issue:

sphinx-immaterial/src/templates/assets/javascripts/components/toc/index.ts

Lines 417 to 418 in 12adf37

	link.style.setProperty("--md-nav__sticky-zindex", zindex.toString())
	nav.style.setProperty(heightProperty, `calc(${heightStr})`)