How to change tabulation size on code review?

While reviewing the code with gitlab merge request web page, tabulation is 8 spaces.

It makes the code difficult to read. How could I move it to 1 or 2 spaces ?

It seems to be impossible to achieve that by available GitLab settings, but this can be hacked using Greasemonkey/Tampermonkey browser extension:

    // ==UserScript==
    // @name     Custom tab-width
    // @version  1
    // @grant    none
    // @include  https://your.gitlab.server.com/*/diffs*
    // ==/UserScript==

    var style = document.createElement("style");
    style.type = "text/css";
    style.innerHTML = "span.line {tab-size:2; -moz-tab-size:2;}";
    document.head.appendChild(style);

or by any other stylish-like extensions which allow you to attach any custom css rules to web pages:

span.line {tab-size:2; -moz-tab-size:2;}