How to add Custom CSS:

https://help.gohighlevel.com/en/support/solutions/articles/48001171841

Code:

<script>
      (function () {
        var funcCount = 0;
        function changeColor() {
          funcCount++;
          var chatWidgets = document.getElementsByTagName('chat-widget');
          if (chatWidgets.length > 0 && !!chatWidgets[0].shadowRoot) {
            var chatWidgetHost = chatWidgets.length > 0 && chatWidgets[0].shadowRoot;
            var style = document.createElement('style');
            style.innerHTML =
              '.lc_text-widget--btn, .lc_text-widget_heading--root, button, .TextInput__Bar:after  { background-color: #4752ac !important; } \
              .TextInput__Textarea:focus ~ label, .TextInput__Input:focus ~ label, .TextInput input:focus ~ .TextInput__Bar:after, \
.TextInput input:focus ~ .TextInput__Bar:before, \
.TextInput textarea:focus ~ .TextInput__Bar:after, \
.TextInput input:focus ~ label, \
.TextInput input:valid ~ label, \
.TextInput textarea:focus ~ label, \
.TextInput textarea:valid ~ label, \
.ConfirmationMessage__PhoneNumber,\
.TextInput textarea:focus ~ .TextInput__Bar:before {color: #4752ac !important;}\
.loader {border-top-color: #4752ac !important;}\
              ';
            chatWidgetHost.appendChild(style);
            return true;
          }
          if (funcCount < 100) {
            setTimeout(changeColor, 0);
          }
          return false;
        }
        if (document.readyState !== 'loading') {
          changeColor();
        } else {
          //somehow window.addEventListener not working with rocket loader
          document.addEventListener('DOMContentLoaded', function () {
            changeColor();
          });
        }
      })();
    </script>