Currently, I am studying angular2 with its material design. One of the modules I am using is md-select for material and here is a snippet of my code:
<md-select>
<md-option value="1">1</md-option>
<md-option value="2">2</md-option>
<md-option value="3">3</md-option>
<md-option value="4">4</md-option>
</md-select>
However, I encountered a https://i.sstatic.net/Nm50A.png
For guidance, I referred to this documentation