dpkg-reconfigure tzdata

ar x dpkg_1.17.23_amd64.deb
tar -zxf data.tar.gz
(or tar -xf data.tar.xz)

Add this file to handle dark themes with Firefox :

cat ~/.mozilla/firefox/randomName.default/chrome/userContent.css
input:not(.tactile-searchbox-input):not(.urlbar-input):not(.textbox-input):not(.form-control):not([type='checkbox']) {
    -moz-appearance: none !important;
    background-color: white;
    color: black;
}

#downloads-indicator-counter {
    color: white;
}

textarea {
    -moz-appearance: none !important;
    background-color: white;
    color: black;
}

select {
    -moz-appearance: none !important;
    background-color: white;
    color: black;
}