docs(material/datepicker): address feedback

Author: mmalerba

src/components-examples/material/datepicker/datepicker-inline-calendar/datepicker-inline-calendar-example.css

@@ -1,4 +1,3 @@
-.demo-inline-calendar {
-  border: 1px solid black;
+.demo-inline-calendar-card {
   width: 300px;
 }

src/components-examples/material/datepicker/datepicker-inline-calendar/datepicker-inline-calendar-example.html

@@ -1,3 +1,4 @@
-<mat-calendar class="demo-inline-calendar" (selectedChange)="selected=$event">
-</mat-calendar>
+<mat-card class="demo-inline-calendar-card">
+  <mat-calendar (selectedChange)="selected = $event"></mat-calendar>
+</mat-card>
 <p>Selected date: {{selected}}</p>

src/components-examples/material/datepicker/index.ts

@@ -2,6 +2,7 @@ import {CommonModule} from '@angular/common';
 import {NgModule} from '@angular/core';
 import {FormsModule, ReactiveFormsModule} from '@angular/forms';
 import {MatButtonModule} from '@angular/material/button';
+import {MatCardModule} from '@angular/material/card';
 import {MatNativeDateModule} from '@angular/material/core';
 import {MatDatepickerModule} from '@angular/material/datepicker';
 import {MatIconModule} from '@angular/material/icon';
@@ -107,6 +108,7 @@ const EXAMPLES = [
   imports: [
     CommonModule,
     MatButtonModule,
+    MatCardModule,
     MatDatepickerModule,
     MatInputModule,
     MatIconModule,