Customizing Mattermost

Troubleshooting
4

Thanks amy.blais, I managed in creating a new custom template as default one.
Now I’m looking for some way to custom the login page.
I know I can customise logo and texts on the System Console, but I wish to customise CSS colours as well, in particular I wish to change the link colours.

I am looking in the source of the mattermost-webapp code where this colour:

.btn.btn-primary {
    background: #2389d7;
    border-color: transparent;
}

and

a {
    color: #2389d7;
    cursor: pointer;
    text-decoration: none;
    word-break: break-word;
}

is specified but I cannot find anything.

Could you help me please?