title: How to use headerClass property of ag-grid in angular?
body: <p>Recently I added <code>a-grid</code> grid to my angular project.</p>
  
  <p>I want to change font-family of header of my grid. I know that there is a property named as <code>headerClass</code> and it is the place of header class definition. but when I applied this property nothing changed to my header font family.</p>
  
  <p>It is html file:</p>
  
  <pre><code>&lt;ag-grid-angular  style="width: 100%; height: 500px;"
                    class="ag-theme-blue"
                    [rowData]="gridOptions.rowData"
                    [columnDefs]="gridOptions.columnDefs"
                    [defaultColDef]="gridOptions.defaultColDef"
                    [enableRtl]="agGridPropeties.enableRTL"
                    [localeText]="localeTextPersian"
                    [rowSelection]="agGridPropeties.rowSelection"
                    [multiSortKey]="agGridPropeties.multiSortKey"
                    [pagination]="agGridPropeties.pagination"
                    [paginationPageSize]="agGridPropeties.paginationPageSize"
  &gt; 
  &lt;/ag-grid-angular&gt;
  </code></pre>
  
  <p>It is my class:</p>
  
  <pre><code>.my-header-class {
    font-family: tahoma;
    font-weight:bold;
  }
  </code></pre>
  
  <p>and it is my ts file:</p>
  
  <pre><code>public gridOptions: any = {
    defaultColDef: {
      resizable: true,
      sortable: true,
      filter: true,
      headerClass: 'my-header-class'
    },
  
    columnDefs : [
      {headerName: 'Make', field: 'make'},
      {headerName: 'Model', field: 'model'},
      {headerName: 'Price', field: 'price'},
      {headerName: 'Country', field: 'country'},
    ],
  
    rowData : [
        { make: 'TOYOTA', model: 'Celica', price: 35000, country:'Japan'},
        { make: 'FORD', model: 'Mondeo', price: 32000, country:'USA'},
        { make: 'BENZ', model: 'C200', price: 100000, country:'Germany'},
        { make: 'LAMBORGHINI', model: 'Aventador', price: 350000, country:'Italy' }
    ]
  }
  </code></pre>
  
  <p>But the column header font family is not as I expected.</p>
  
  <p>Do you have any Idea?</p>