Can anyone help with this Google Calendar script please?

I am seeking a way to restyle the google calendar by trying to add a different background color to each day of the month, closest I am getting is this code:

@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document url-prefix("http://www.google.com/calendar") {

.tg-today, .bg-exists .tg-today, .st-bg-today {
 background-color:#53abdf !important;
}
.lv-today {
/* background-color:#ffffcc !important;*/
}


}

taken from this small artticle:

Google Calendar - MAKE TODAY BG COLOR OBVIOUS - Themes and Skins for google.com - userstyles.org

The way I see it, if this code can change the bg color for one day then why can’t it work for ANY day “ahead” of time?