Checathlon theme old pink color. You can put these styles in child theme style.css or in the Customizer additional CSS section.

checathlon-old-pink-color.css

.highlight-color,
.jetpack-testimonial .entry-inner .icon,
.before-footer-widgets-wrapper .icon,
.checathlon_widget_pricing .icon {
	color: #ff1654;
}

a,
a:visited {
	color: #ff1654;
}

.page-template-team-page .entry-title a:hover,
.page-template-team-page .entry-title a:focus,
.page-template-team-page .entry-title a:active {
	color: #ff1654;
}

@media screen and (min-width: 62.875em) {

	.main-navigation a:hover,
	.main-navigation a:focus,
	.main-navigation a:active {
		color: #ff1654;
	}

	.main-navigation .current-menu-item > a,
	.main-navigation .current-menu-ancestor > a {
		color: #ff1654;
	}

}

button,
input[type="button"],
input[type="reset"],
input[type="submit"],
a.button,
a.button:visited {
	background-color: #ff1654;
}

a.button-secondary:hover,
a.button-secondary:focus,
a.button-secondary:active,
a.edd-cart-saving-button.button:hover,
a.edd-cart-saving-button.button:focus,
a.edd-cart-saving-button.button:active,
.edd-download-info .button.edd-demo-link:hover,
.edd-download-info .button.edd-demo-link:focus,
.edd-download-info .button.edd-demo-link:active,
body .wp-core-ui .quicktags-toolbar input.button.button-small:hover,
body .wp-core-ui .quicktags-toolbar input.button.button-small:focus,
body .wp-core-ui .quicktags-toolbar input.button.button-small:active {
	background-color: #ff1654;
}

.menu-toggle,
.menu-toggle:hover,
.menu-toggle:focus,
.menu-toggle:active {
	color: #ff1654;
}

.archive-description:before {
	border-bottom-color: #ff1654;
}