Template:Multiple image/styles.css

/* {{pp-template}} */
/* this is a block */
.multiimageinner {
	display: flex;
	flex-direction: column;
	/* --- ADDED BORDER AND BACKGROUND STYLES BELOW --- */
	border: 1px solid #c8ccd1 !important; 
	background-color: #f8f9fa !important;  
	padding: 5px;
	font-size: 85%;
	box-sizing: border-box;
}

.trow {
	display: flex;
	flex-direction: row;
	clear: left;
	flex-wrap: wrap;
	width: 100%;
	box-sizing: border-box;
}

/* this is a cell */
.tsingle {
	margin: 1px;
	float: left;
}

/* Strips native frames out of the inner images so they don't look nested */
.tsingle figure[typeof~="mw:File/Thumb"], 
.tsingle .thumbinner {
	margin: 0 !important;
	background: none !important;
	border: none !important;
}

.theader {
	clear: both;
	font-weight: bold;
	text-align: center;
	align-self: center;
	background-color: transparent;
	width: 100%;
}

.thumbcaption {
	background-color: transparent;
}

.text-align-left {
	text-align: left;
}

.text-align-right {
	text-align: right;
}

.text-align-center {
	text-align: center;
}

@media all and ( max-width: 720px ) {
	.thumbinner {
		width: 100% !important;
		box-sizing: border-box;
		max-width: none !important;
		align-items: center;
	}
	.trow {
		justify-content: center;
	}
	.tsingle {
	    float: none !important;
	    max-width: 100% !important;
	    box-sizing: border-box;
	    text-align: center;
	}
	.tsingle .thumbcaption {
		text-align: left;
	}
	.trow > .thumbcaption {
		text-align: center;
	}
}

@media screen {
	.multiimageinner .thumbimage {
		background-color: inherit;
	}
	html.skin-theme-clientpref-night
		.multiimageinner
		.thumbimage:not([style*="background-color"])
		span:not(.skin-invert-image):not(.skin-invert):not(.bg-transparent)
		img,
	html.skin-theme-clientpref-day
		.multiimageinner
		.thumbimage:not([style*="background-color"])
		span:not(.bg-transparent)
		img
	{
		background-color: white;
	}
}

@media screen and (prefers-color-scheme: dark) {
	html.skin-theme-clientpref-os
		.multiimageinner
		.thumbimage:not([style*="background-color"])
		span:not(.skin-invert-image):not(.skin-invert):not(.bg-transparent)
		img
	{
		background-color: white;
	}
}

/* Forces inner image blocks to respect the horizontal grid layout */
.trow figure.mw-default-size,
.trow figure[typeof~="mw:File/Thumb"],
.trow figure {
    display: inline-block !important;
    margin: 2px !important;
    float: none !important;
    vertical-align: top;
}

/* Keeps row layouts properly flexible and side-by-side */
.trow {
    display: flex !important;
    flex-direction: row !important;
    flex-wrap: nowrap !important;
    justify-content: flex-start;
    align-items: flex-start;
    width: 100%;
}