title: How to override global border color styles for disabled Material UI TextField?
body: <p>I'm trying to override the global style for the Mui TextField components that are disabled, but I can't get the border color to change.</p>
  
  <p>I've managed to change the label color if the field is disabled, but not the border color. Here is what I have so far:</p>
  
  <pre><code>export const theme = createMuiTheme({
    overrides: {
      // For label
      MuiInputLabel: {
        root: {
          '&amp;$disabled': {
            color: '#000000',
          },
        },
      },
      // For border color of field (doesn't work)
      MuiTextField: {
        root: {
          '&amp;$disabled': {
            borderColor: '#FFFFFF'
          },
        },
      },
    },
  });
  </code></pre>
  
  <p>I've tried all kinds of variations, including,</p>
  
  <pre><code>    MuiOutlinedInput: {
        root: {
          fieldset: {
            borderColor: '#FFFFFF',
          },
        }
      }
  </code></pre>
  
  <p>But this only changes the border color of non-disabled fields. What am I doing wrong here?
  Here is how it looks:
  <a href="https://i.stack.imgur.com/PlMD9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PlMD9.png" alt="img"></a></p>