I am trying to remove the extra space where the label was supposed to be (the green part)
This seems to be the CSS for the date-picker, now here comes the problem :

I added this in the .css file, but it doesn't seem to do anything.
.mat-form-field-appearance-fill .mat-form-field-flex {
padding-top: 0.0em !important;
padding-right: 0.0em !important;
padding-bottom: 0px !important;
padding-left: 0.0em !important; 
}
Yes, the CSS file is linked to the html file, when I try to modify something else it works.
Any ideas why?
EDIT: I am using the Angular Material Date-picker
This is the HTML
<mat-form-field appearance="fill">
  <mat-date-range-input [formGroup]="range" [rangePicker]="picker">
    <input matStartDate formControlName="from" placeholder="From">
    <input matEndDate formControlName="to" placeholder="To">
  </mat-date-range-input>
  <mat-datepicker-toggle matSuffix [for]="picker"></mat-datepicker-toggle>
  <mat-date-range-picker #picker></mat-date-range-picker>
  <mat-error *ngIf="range.controls.from.hasError('matStartDateInvalid')">Invalid starting date!</mat-error>
  <mat-error *ngIf="range.controls.to.hasError('matEndDateInvalid')">Invalid ending date!</mat-error>
</mat-form-field>