youtube.com.user.css

:root {
	--yt-icon-active-color: #3daee9 !important;
	/* --iron-icon-fill-color: #ffffff !important; */
}

paper-button[subscribed].ytd-subscribe-button-renderer {
	background-color: var(--yt-icon-active-color);
	color: #eff0f1;
	transition: .25s background-color;
}

paper-button[subscribed].ytd-subscribe-button-renderer span {
	color: inherit;
}

/** Colorful Rating Bar with Return Youtube Dislike extension **/

:root {
	--colorful-rating-bar-like-color: #009900;
	--colorful-rating-bar-dislike-color: #ff2929;
}

/* Bar */
#ryd-bar {
	background: var(--colorful-rating-bar-like-color) !important;
}

#ryd-bar-container {
	background: var(--colorful-rating-bar-dislike-color) !important;
}

/* Like button */
ytd-toggle-button-renderer.style-default-active:nth-of-type(1):not(:hover) a.yt-simple-endpoint.ytd-toggle-button-renderer {
	color: var(--colorful-rating-bar-like-color) !important; 
}

ytd-toggle-button-renderer:nth-of-type(1):not(:hover) yt-icon-button.style-default-active button yt-icon svg,
ytd-toggle-button-renderer:nth-of-type(1):not(:hover) yt-icon-button[aria-pressed="true"] button yt-icon svg {
	fill: var(--colorful-rating-bar-like-color) !important;
}

/* Dislike button */
ytd-toggle-button-renderer.style-default-active:nth-of-type(2):not(:hover) a.yt-simple-endpoint.ytd-toggle-button-renderer {
	color: var(--colorful-rating-bar-dislike-color) !important; 
}

ytd-toggle-button-renderer:nth-of-type(2):not(:hover) yt-icon-button.style-default-active button yt-icon svg,
ytd-toggle-button-renderer:nth-of-type(2):not(:hover) yt-icon-button[aria-pressed="true"] button yt-icon svg {
	fill: var(--colorful-rating-bar-dislike-color) !important;
}

/* Hover on Like/Dislike buttons */
ytd-toggle-button-renderer.style-default-active:hover a.yt-simple-endpoint.ytd-toggle-button-renderer,
ytd-toggle-button-renderer.style-default-active.force-icon-button a.ytd-toggle-button-renderer:hover #text.ytd-toggle-button-renderer {
	color: var(--yt-spec-icon-inactive) !important; 
}

ytd-toggle-button-renderer:hover yt-icon-button.style-default-active button yt-icon svg,
ytd-toggle-button-renderer:hover yt-icon-button[aria-pressed="true"] button yt-icon svg {
	fill: var(--yt-spec-icon-inactive) !important;
}

/* Compatibility: Enhancer for YouTube's Deep Dark theme */
ytd-toggle-button-renderer:not(.style-default-active) a.yt-simple-endpoint.ytd-toggle-button-renderer:hover * {
	color: var(--main-color) !important;
	fill: var(--main-color) !important;
}

Return YouTube Dislike v3 comes with its own like/dislike + rating bar colorizing options
It's fairly basic (no custom colors code support yet), but can safely switch over to using those instead if desired