Variables in CSS Selectors

The selectors for links on Hacker News are as below,where 'xxxxxxx' is a random 7 digit number.
---

#\32 xxxxxxx .storylink {
}

---
How would I create a variable to stand in for that 7 digit number?
here's my current userstyle
---

/* ==UserStyle==
@name         Modern Hacker News Dark
@namespace    github.com/losuler/hacker-news-userstyle
@homepageURL  https://github.com/losuler/hacker-news-userstyle
@description  A modern dark Hacker News userstyle
@updateURL    https://github.com/losuler/hacker-news-userstyle/blob/master/modern-hacker-news-dark.user.css
@version      1.0.0
@preprocessor stylus
==/UserStyle== */
@-moz-document url-prefix("https://news.ycombinator.com") {
/* reset */
:root{
        --bg:#000000;
        --text:#CCCCCC;
        --fsize:18px;
        --container-bg:#000044;
        --container-text:#ffffff;
    }

    body{
        background-color: var(--bg);
    }
    #hnmain,#hnmain table,#hnmain > tbody > tr > td,a link,.storylink{
        background-color: var(--container-bg);
        color:var(--container-text);
        font-size:var(--fsize);
    }
}

---