WordPress/wp-content/themes/twentytwentyone/assets/sass/04-elements/links.scss

/*
 * text-underline-offset doesn't work in Chrome at all 👎
 * But looks nice in Safari/Firefox, so let's keep it and
 * maybe Chrome will support it soon.
 */
a {
	cursor: pointer;
	color: var(--wp--style--color--link, var(--global--color-primary));
	text-underline-offset: 3px;
	text-decoration-skip-ink: all;
}

a:hover {
	text-decoration-style: dotted;
	text-decoration-skip-ink: none;
}

.site a:focus:not(.wp-block-button__link):not(.wp-block-file__button) {

	/* Only visible in Windows High Contrast mode */
	outline: 2px solid transparent;

	text-decoration: underline 1px dotted currentColor;
	text-decoration-skip-ink: none;
	background: rgba(255, 255, 255, .9);

	// Change text color when the body background is dark.
	.is-dark-theme & {
		background: var(--global--color-black);
		color: var(--global--color-white);
		text-decoration: none;

		.meta-nav {
			color: var(--wp--style--color--link, var(--global--color-white));
		}
	}

	// Change colors when the body background is white.
	.has-background-white & {
		background: rgba(0, 0, 0, .9);
		color: var(--wp--style--color--link, var(--global--color-white));

		.meta-nav {
			color: var(--wp--style--color--link, var(--global--color-white));
		}
	}

	&.skip-link {

		/* Only visible in Windows High Contrast mode */
		outline: 2px solid transparent;
		outline-offset: -2px;

		&:focus {
			color: #21759b;
			background-color: #f1f1f1;
		}
	}

	&.custom-logo-link {
		background: none;
	}

	img {
		outline: 2px dotted var(--wp--style--color--link, var(--global--color-primary));
	}
}

// Enforce the custom link color even if a custom background color has been set.
// The extra specificity here is required to override the background color styles.
.has-background {
	// Target both current level and nested block.
	.has-link-color a,
	&.has-link-color a {
		color: var(--wp--style--color--link, var(--global--color-primary));
	}
}