Customer area & login popup CSS

Site URL: https://weareluxus.co.uk

I need help changing everything about the customer login popup in horizon. ie:

I've tried to start with the sign in button and this is as far as I've got (not even sure this is close):

button.Button-container-BtFfe {
    background-color: #e08700;
    border-radius: 3px;
    color: #000000;
    display: block;
    width: 100%;
    font-weight: 700;
    line-height: 22px;
    padding: 11px;
    margin-top: 22px;
  text-transform: uppercase;
}

Any help appreciated. TIA

Andrew

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