Stackedit.io - Justify

README.md

Settings -> Extensions -> UserCustom

userCustom.onReady = function() {
    $('head').append(`<style>p, pre, blockquote {
      text-align: justify;
    }
    blockquote p, li p {
      text-indent: 0
    }</style>`);
};

Settings -> Advanced -> PDF template

<style>
    p, pre, blockquote {
      text-align: justify;
    }
    blockquote p, li p {
      text-indent: 0
    }
</style>