title: mat-select options became transparent after updating to angular material v7
body: <p>I have been working on a web app for the past few weeks and we wanted to make some updates.  We updated the project and all of its node modules and when I got everything working again the select drop down's options were transparent and the mat-cards lost their drop shadow.</p>
  
  <p>Did something change in the material update that made the styles act like this?</p>
  
  <p><a href="https://i.stack.imgur.com/2X3XR.png" rel="noreferrer"><img src="https://i.stack.imgur.com/2X3XR.png" alt="enter image description here"></a></p>