title: Text field from Vuetify has no underline
body: <p>I am trying to use vuetify's text field. It looks like this:
  <a href="https://i.stack.imgur.com/2Md2I.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2Md2I.png" alt="before_focus"></a></p>
  
  <p>After applying focus it looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/Yb1vc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Yb1vc.png" alt="after_focus"></a></p>
  
  <p>I have read <a href="https://stackoverflow.com/questions/45579658/vuetify-text-field-border-missing">this</a> this, but my app IS wrapped in v-app. Is there anything else I could try?</p>
  
  <p>HINT:
  Dark theme doesn't work for me as well,but for example, I can use classes like "red", "text--red", to apply colors.</p>
  
  <p>Proof, that there is v-app involved below:
  <a href="https://i.stack.imgur.com/dwhNb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dwhNb.png" alt="enter image description here"></a></p>
  
  <p>EDIT:
  I tried to wrap it with v-content as well, but it didn't help.</p>
  
  <pre><code>&lt;v-app&gt;
    &lt;v-content&gt;
      &lt;router-view&gt;&lt;/router-view&gt;
    &lt;/v-content&gt;
  &lt;/v-app&gt;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/zi10Z.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zi10Z.png" alt="enter image description here"></a></p>