That is part of the Material styling. You can customize this by CSS – var(–smart-button-text-transform); CSS variable should be set to ”;
For the window, the var(–smart-window-footer-button-width) CSS variable controls the width of the buttons displayed in the Window’s footer.
Please, look at https://www.htmlelements.com/docs/window-css/. Scroll to the bottom of the page, where we have an example. I will also copy it here to show you how to apply CSS variables