zotero/scss/components/_mainWindow.scss

:is(panel):not(#autoscroller)::part(content) {
	--panel-background: var(--material-toolbar);
}

#main-window {
	min-width: max(var(--width-of-fixed-components) + $min-width-items-pane, $min-width-tabs-deck);
	min-height: 300px;
}

#main-window.stacked {
	min-height: calc(var(--height-of-fixed-components) + $min-height-items-pane + $height-toolbar);
}

#zotero-pane {
	min-width: 0;
	min-height: 0;
}

#zotero-pane-stack > hbox {
	// Let window chrome, tabs, and toolbar shrink even when sidebars overflow
	min-width: 0;
}
#browser, #zotero-pane-stack, #zotero-trees {
	min-height: 0;
}

#zotero-pane-overlay {
	background: rgba(0,0,0,.3);
}

#zotero-pane-progress-box {
	background: var(--color-sidepane);
	border-radius: 5px;
	border: var(--color-panedivider);
	height: 30px;
	width: 300px;
}

#zotero-pane-progressmeter-container {
	padding: 10px;
}

#zotero-layout-switcher {
	flex-grow: 1;
	flex-shrink: 1;
	min-width: 0;

	/*
		Fx115: make panes occupy all available width/height after layout switch
		or splitter expand/collapse.
		The splitter element stores state in the style attribute's width/height
		properties, and if we remove them, the splitter breaks. So we override
		them here with !important.
	*/
	&[orient="horizontal"] :is(#zotero-items-pane-container, #zotero-item-pane) {
		height: auto !important;
	}

	&[orient="vertical"],
	&[orient="vertical"] :is(#zotero-items-pane-container, #zotero-item-pane) {
		width: -moz-available !important;
		/* min-width: 0 is required here to allow the pane to shrink in Stacked view,
		   but the child #zotero-items-pane sets a larger min-width, and the splitter
		   follows that instead of this. */
		min-width: 0 !important;
	}
}