What is the expected behavior?
The Mat label is meant to float up, sit above the outline and have a white background

What is the current behavior?
The mat label is floating up but doesn't have a white background.

What are the steps to reproduce?
Add a mat input with appearance outline
<mat-form-field appearance="outline"> <mat-label>{{question.label}}</mat-label> <input matInput [placeholder]="question.placeholder" [formControlName]="question.key" [id]="question.key" [type]="question.type"> ion.type"> </mat-form-field>
Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Angular Material version 7.1.0
Is there anything else we should know?