You can style your cart icon with Ecwid to your liking. You can change for example:

You will find the instructions under this link: https://support.ecwid.com/hc/en-us/articles/360000013659-Adding-shopping-bag-to-a-custom-site

Watch the video below on how to ad a sticky cart icon to your store:

<div data-fixed="TRUE"
data-fixed-position="TOP_RIGHT"
data-fixed-shape="VALUE"
data-horizontal-indent="VALUE"
data-vertical-indent="VALUE" class="ec-cart-widget"></div>
<div>
<script data-cfasync="false" type="text/javascript"
src="https://app.ecwid.com/script.js?STORE_ID&data_platform=code"
charset="utf-8"></script><script>Ecwid.init();</script></div>