I used to do this for override this date picker ( ng2-date-picker ) an other css from module that are hard to change :
In *.ts
constructor(private elRef: ElementRef) {}
couleurBouton() {
var header = this.elRef.nativeElement.querySelector('.dp-nav-header');
if (header) {
header.style.color = "#c8960f";
}
var current = this.elRef.nativeElement.querySelector('.dp-current-month');
if (current) {
current.style.border = "1px solid #c8960f";
}
var selected = this.elRef.nativeElement.querySelector('.dp-selected');
if (selected) {
selected.style.background = "#c8960f";
}
}
In template :
<dp-date-picker (click)="couleurBouton()" theme="dp-material" mode="month" [(ngModel)]="selectedDate" placeholder="Date par mois" [config]="datePickerConfig"></dp-date-picker>
If someone have a solution more clean it will be a pleasure