UnfoldingCSS:StyleBox

:root {
    /* ***** PAGE OPTIONS **** */
    --page-size: A4; 

    /* ***** FONTS ****** */
    --title-font: 'Serif';
    --body-font: 'Sanserif';
    --code-font: 'Monospace';
    --quote-font: 'Serif';
    --footnote-font: 'Sanserif';
    --page-number-font: 'Monospace';
    

    /* ****** COLOR ****** */
    --background-color: #ffffff;
    --text-color: 'MidnightBlue';


    /* ***** CONTENT ****** */
    --PUB-title: 'PUB Title';

}

@page {
    size: var(--page-size);
    margin-top: 1.5cm;
    margin-bottom: 1.5cm;
}


@page:first{

    @right-middle {
        content: none;
    }    

    @right-top {
        content: none;
    }

}

@page:right {

    margin-left: 35mm;
    margin-right: 20mm;

    @right-middle {
        content: counter(page);
        font-family: var(--code-font);
    }    

    @right-top {
        content: var(--PUB-title);
        font-family: var(--title-font);
        margin-right: 0.8cm;
        writing-mode: vertical-rl;
        text-orientation: mixed;
    }
    
}


@page:left {

    margin-right: 35mm;
    margin-left: 20mm;

    @left-middle {
        content: counter(page);
        font-family: var(--title);
    }    

    @left-top {
        content: "TITLE";
        font-family: Serif;
        margin-right: 0.8cm;
        writing-mode: vertical-rl;
        text-orientation: mixed;
    }
    
}


p:nth-of-type(3n) {
  border: 2px solid orange;
  margin-left: -10px;
}