Add SVG as logo in The7 theme

function.php

//to able to use svg you can install following plugin https://uk.wordpress.org/plugins/svg-support/
function presscore_get_logo_image( $logos = array(), $class = '' ) {	

	if ( ! is_array( $logos ) ) {
		$logos = array( $logos );
	}

	// get default logo
	foreach ( $logos as $logo ) {
		if ( $logo ) {
			$default_logo = $logo;
			break;
		}
	}
	if ( empty( $default_logo ) ) {
		return '';
	}
	$alt = get_bloginfo( 'name' );
	$my_logo = '<img class="my_svg_logo ' . esc_attr( $class . ' preload-me' ) . '"src="' . $default_logo[0]. '" alt="' . esc_attr(  $alt ) . '">';
	return $my_logo;
}

style.css

.my_svg_logo{
  height: 40px !important;
}