Wikipedia:Today's featured article/styles.css

.tfa-header-left {
    width: 60%;
    padding: 0.5em 1em;
    border: 1px solid #a3b1bf;
    background-color: #e6f2ff;
    color: inherit;
    vertical-align: top;
}

.tfa-header-right {
    padding: 0.5em 1em;
    border: 1px solid #a3b1bf;
    background-color: #e6f2ff;
    color: inherit;
    vertical-align: top;
}

.tfa-archive {
    border: 1px solid #bfb6a3;
    padding: 0.5em 1em;
    background-color: #fffaf0;
    color: inherit;
}

.mp-tfa-h2 {
    margin: 0.5em;
    background: #cef2e0;
    font-family: inherit;
    font-size: 120%;
    font-weight: bold;
    border: 1px solid #a3bfb1;
    color: inherit;
    padding: 0.2em 0.4em;
}

.MainPageBG {
    margin-top: 4px;
    border: 1px solid #cef2e0;
    padding: 0;
    background: #f5fffa;
    vertical-align: top;
    color: inherit;
}

.mp-tfa {
    padding: 0.1em 0.6em;
}

@media screen {
	html.skin-theme-clientpref-night .tfa-header-right,
	html.skin-theme-clientpref-night .tfa-header-left {
		background-color: #0d1a27;
		border-color: #404E5C;
	}
	
	html.skin-theme-clientpref-night .tfa-archive {
		background-color: #2d2212;
		border-color: #5C5440;
	}
	
	html.skin-theme-clientpref-night .mp-tfa-h2 {
		background: #104437;
		border-color: #405C4E;
	}
	
	html.skin-theme-clientpref-night .MainPageBG {
		background: #0b1e1c;
		border-color: #0D3120;
	}
}

@media screen and (prefers-color-scheme: dark) {
	html.skin-theme-clientpref-os .tfa-header-right,
	html.skin-theme-clientpref-os .tfa-header-left {
		background-color: #0d1a27;
		border-color: #404E5C;
	}
	
	html.skin-theme-clientpref-os .tfa-archive {
		background-color: #2d2212;
		border-color: #5C5440;
	}
	
	html.skin-theme-clientpref-os .mp-tfa-h2 {
		background: #104437;
		border-color: #405C4E;
	}
	
	html.skin-theme-clientpref-os .MainPageBG {
		background: #0b1e1c;
		border-color: #0D3120;
	}
}