Can tabs preview styling using css?

[YudhaStacy]

can custom like border radius, font size?

[soul4kills]

You can, but you would need modify Firefox directly and add your css in userContent.css.

Here's a sample of my styling.

div.popup[style*="--fg"][style*="--bg"] {
	opacity: 0.95 !important;
	visibility: collapse;
		&:has(div[style*="background-image: url("][style*="opacity: 1;"]) {
		visibility: visible !important;
		border: 1px solid var(--tab-selected-outline-color);
		box-shadow: 0 1px 20px -5px var(--tab-selected-outline-color)!important;
	}
	.header { visibility: collapse !important; }
	@media not (-moz-bool-pref: "sidebar.position_start") { left: auto !important;  right: calc(var(--uc-sidebar-hover-width) - var(--uc-sidebar-width)) !important;}
	@media (-moz-bool-pref: "sidebar.position_start") { right: auto !important; left: calc(var(--uc-sidebar-hover-width) - var(--uc-sidebar-width)) !important; }
}
	/* Tab preview fix alignment when uc.chromeless is toggled to true */
@media (-moz-bool-pref: "uc.chromeless") {
	div.popup[style*="--fg"][style*="--bg"] {
		@media not (-moz-bool-pref: "sidebar.position_start") { left: auto !important; right: var(--uc-sidebar-hover-width) !important;}
		@media (-moz-bool-pref: "sidebar.position_start") { right: auto !important; left: var(--uc-sidebar-hover-width) !important;}
	}
}
	/* Fix pop-in-page tab preview alignment - Specifically when maximized or uc.full.tabs is true */
@media only screen and (width: 109.25em), (-moz-bool-pref: "uc.full.tabs") { /* Adjustments  needed for user specific screen size */
	div.popup[style*="--fg"][style*="--bg"]{
		@media not (-moz-bool-pref: "sidebar.position_start") { left: auto !important; right: 0px !important;}
		@media (-moz-bool-pref: "sidebar.position_start") { right: auto !important; left: 0px !important;}
	}
}
#sdbr_preview_root {
	background: transparent !important;
	@media not (-moz-bool-pref: "sidebar.position_start") { left: auto !important; right: 0px !important; }
	@media (-moz-bool-pref: "sidebar.position_start") { right: auto !important; left: 0px !important; }
}

Only a small part of it is cosmetic. The rest are media queries that determine size of my sidebar and what side it's on then automatically adjusts offsets according to that. So ignore the media queries.

Hope this helps point you in the right direction.

[YudhaStacy]

thanks for the reply