Thank you for sharing the screenshot.
Please add the following css rule in Custom CSS section to solve small screen issue:
@media (max-width:575px) {
#sp-header, #sp-header .logo {
height: 72px;
}
}
About helix quickstart logo svg: It depends on how you have created the svg. If you create the svg from scratch in any vector graphics application it should look cleaner like the quickstart one. Also the quickstart one has less anchors points.
Kindly do let me know if that helps you or if you have any queries.