Custom Firefox Quantum Dev Tools (Network tab)

userChrome.css

/* https://www.userchrome.org/what-is-userchrome-css.html */
/* Preview: https://imgur.com/kZmJ75T */

.requests-list-file.requests-list-column {  
    background-color: #48654b1a !important;
    color: #ddd !important;
    min-width: 300px !important;
    direction: rtl !important;
}
.requests-list-file.requests-list-column[title*='/web-api'] {
    color: #5177ff !important;
}
.requests-list-method.requests-list-column {
    min-width: 45px !important;
    width: 45px !important;
    font-size: 8px !important;
}
.requests-list-status.requests-list-column {
    min-width: 35px !important;
    width: 35px !important;
}
.requests-list-domain.requests-list-column {
    min-width: 100px !important;
    width: 100px !important;
}
.requests-list-transferred.requests-list-column {
    min-width: 60px !important;
    width: 60px !important;
}
.requests-list-size.requests-list-column {
    min-width: 60px !important;
    width: 60px !important;
    color: #467209;
}
.requests-list-type.requests-list-column[title^='text/html'] {
    color: #91acf2 !important;
}
.requests-list-type.requests-list-column[title^='application/javascript'] {
    color: #c260e5 !important;
}
.requests-list-type.requests-list-column[title^='text/css'] {
    color: #e86d30 !important;
}
.requests-list-type.requests-list-column[title^='application/json'] {
    color: #9be82f !important;
}
.requests-list-type.requests-list-column[title^='image/'] {
    color: #d3ca61 !important;
}
.requests-list-cause.requests-list-column[title='xhr'] {
    color: #d3ca61 !important;
}

#requests-list-status-header-box,
#requests-list-method-header-box
{
    text-indent: -9999px !important;
    overflow: hidden !important;
}