 look
    like:</p>

    <pre><code>
    lex:add_style('custom_whitespace',
                  lexer.styles.whitespace .. {back = lexer.colors.grey})
    </code></pre>

    <p>Remember to refrain from assigning specific colors in styles, but in this
    case, all user color themes probably define <code>colors.grey</code>.</p>

    <p><a id="lexer.Line.Lexers"></a></p>

    <h4>Line Lexers</h4>

    <p>By default, lexers match the arbitrary chunks of text passed to them by
    Scintilla. These chunks may be a