Vaadin Inject Custom CSS to prevent FontIcons on core components

CssStyles.css

.v-checkbox > input ~ label:after {
    content: "\2714" !important;
    font-family: default !important;
    color: transparent;
    -webkit-transition: color 100ms;
    -moz-transition: color 100ms;
    transition: color 100ms;
}

.v-tree-node-expanded > .v-tree-node-caption > div:before {
    -webkit-transform: rotate(90deg);
    -moz-transform: rotate(90deg);
    -ms-transform: rotate(90deg);
    -o-transform: rotate(90deg);
    transform: rotate(90deg);
    content: "\25b6" !important;
    font-family: default !important;
}

.v-tree-node > .v-tree-node-caption > div:before {
    content: "\25b6" !important;
    font-family: default !important;
    display: inline-block;
    width: 0.5em;
    text-align: center;
    margin: 0 0.6em 0 0.8em;
    -webkit-transition: all 100ms;
    -moz-transition: all 100ms;
    transition: all 100ms;
}

.v-button-prevyear:before {
    font-family: default !important;
    content: "\ab" !important;
}

.v-button-prevmonth:before {
    font-family: default !important;
    content: "\2039" !important;
}

.v-button-nextyear:before {
    font-family: default !important;
    content: "\bb" !important;
}

.v-button-nextmonth:before {
    font-family: default !important;
    content: "\203a" !important;
}

.v-datefield-huge [class*="button"]:before {
    font-family: default !important;
    content: "\25A4" !important;

}
.v-datefield [class*="button"]:before {
    font-family: default !important;
    content: "\25A4" !important;
}


.v-filterselect [class$="button"]:before {
    font-family: default !important;
    -webkit-transform: rotate(90deg);
    -moz-transform: rotate(90deg);
    -ms-transform: rotate(90deg);
    -o-transform: rotate(90deg);
    transform: rotate(90deg);
    content: "\25b6" !important;
    top: 50%;
    font-size: 40px;
}

.v-filterselect-large [class$="button"]:before {
    font-family: default !important;
    content: "\25b6" !important;
    top: 50% !important;
    font-size: 55px !important;
}

.v-filterselect-huge [class$="button"]:before {
    font-family: default !important;
    content: "\25b6" !important;
    top: 50% !important ;
    font-size: 80px;
}

.v-filterselect-compact [class$="button"]:before, .updater .v-filterselect-small [class$="button"]:before {
    font-family: default !important;
    content: "\25b6" !important;
    top: 50%;
}

.v-filterselect-tiny [class$="button"]:before {
    font-family: default !important;
    content: "\25b6" !important;
    top: 50%;
}

.v-filterselect-suggestpopup div[class*="prev"]:before {
    content: "\25B2" !important;
}

.v-filterselect-suggestpopup div[class*="next"]:before {
    content: "\25BC" !important;
}

UIInjectStyles.java

//You should place this code on your UI
//if you want you can add also the version check here
if (Page.getCurrent().getWebBrowser().isIE()){
    Page.getCurrent().getStyles().add(new ClassResource("iefix-vaadinfa.css"));
}