Running Ionic4 on Angular is pretty simple as well as for Vue. Regarding the docs for Angular you can add a global variable file located in src/theme/variable.scss and override whatever you want. However this seems not to be possible for Vue.
Looking at segment-button.md.vars.scss there is a variable called $segment-button-md-line-height which should be overrideable. Again, running Angular this is possible which, however, isn’t possible for Vue.
Due to web components shadow DOMs I’m not able to override any styles. So, what would be (the best) solution to pass in styles?