How to set font-style and font-size for all pages in ionic 3?

First you must import Style at this path
F:\Project\DemoApp\node_modules\ionic-angular\fonts

Then add font into Variable.scss before @import “roboto”;(we get this as default )
@import “tradegothic”;

And add this lines in app.scss

ion-app.ios {
font-family: TradeGothic !important;
font-size: 15px;
}

ion-app.android {
font-family: TradeGothic !important;
font-size: 15px;
}

then re run app