Hi @JonC,
Thank you for reaching out to us. This would require custom CSS as this is not a theme feature by default and is outside of our support scope, but we will do our best to help you getting started with the customization but we will not be able to implement it. To change the button style to X button style, try adding the following code in the Theme Options > CSS:
.calendly-badge-content {
border-radius: 0.35em !important;
font-size: 15px !important;
background-color: #363636 !important;
box-shadow: 0em 0.15em 0.65em 0em rgba(0,0,0,0.25) !important;
padding: 10px 20px !important;
font-family: "Source Sans Pro",sans-serif !important;
font-weight: normal !important;
}
Here are some related links for further reading, this could help you in finding and implementing some CSS fixes:
Don’t forget to clear all caches including your browser’s cache after adding the code. Hope this helps!