1. Once you have JSON Reader extension installed on your web browser, access the options page for the extension.

2. On the custom style section, add the following css properties:

.CodeMirror {
  font-family: monaco, Consolas, Menlo, Courier, monospace;
  font-size: 16px;
  line-height: 1.5em;
  background-color: #19002e !important;
  color: #8d659c !important;
  border: none;
}
.CodeMirror-gutters {
  background-color: #19002e !important;
}
.CodeMirror-linenumber {
  color: #00ffb7 !important;
}

span {
  color: #399ee6 !important;
}
span.cm-property {
  color: #ff0e82 !important;
}
span.cm-atom {
  color: #ff0e82 !important;
}
span.cm-number {
  color: #bd93f9 !important;
}
span.cm-variable {
  color: #50fa7b !important;
}
span.cm-string {
  color: #a470d8 !important;
}
span.cm-comment {
  color: #620ca2 !important;
}

.extras .icon svg {
  fill: #00ffb7 !important;
}