ah
So you want to change the color of the svg. This is not easily possible. Lay theme uses this markup for showing an svg image:
<img src="http://laytheme.dev/wp-content/uploads/2016/10/Bugger_King_Logo.svg" alt="Lay Theme">
If you open the svg with a texteditor you see the svg's markup which looks just a bit like HTML markup. If you copy that markup into "Custom HTML at top" (in "Custom html and css") you will have the svg markup directly in your website. Of course this is not the site title and you would need to position this svg by yourself using css. Example:
.your-svgs-class{
position: fixed;
top: 10px;
left: 50%;
transform: translateX(-50%);
z-index: 2;
}
Now that you got your svg markup in your website you can do things like:
svg path{
fill: blue!important;
}
Here's more info on css and svg
https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started/SVG_and_CSS