System Font CSS is set of @font-face rules that let you use the native system font of the OS running the browser.

body {
    font-family: system-ui;
}

system-font.css offers eight variations of the system-ui font family; light (300) light italic, normal (400), normal italic, medium (500), medium italic, bold (700), and bold italic.

blockquote {
    font: italic 300 system-ui;
}

p {
    font: 400 system-ui;
}

This package can be installed with:

• npm: npm install --save system-font-css

When installed with npm, system-font.css will create both a SCSS and LESS partial for easy importing:

@import 'system-font';

OSX has used three system typefaces. Since El Capitan it has used San Fransisco. In Yosemite it used Helvetica Neue. From Mavericks back to Kodiak it used Lucida Grande.

Windows has used four system typefaces. Since Vista it has used Segoe UI. In XP, it used Tahoma, which oddly enough does not have an italic variation. From Windows ME back to Windows 3.1 it used Microsoft Sans Serif. Finally, from Windows 2.0 back to Windows 1.0 it used Fixedsys. Neither Microsoft Sans Serif or Fixedsys are included in this set, with apologies.

Also, for those of opposed to joy, remember that Internet Explorer 8 does not support local @font-face rules. Therefore, should you need to reference system fonts in that browser then you will need to do so from the font declaration.

body {
    font-family: system-ui, "Segoe UI", Tahoma;
}

Android has used two system typefaces. Since Ice Cream Sandwich it has used Roboto. From Jelly Bean back to Cupcake it used Droid Sans, which also lacks an italic variation. Do you suppose OS developers dislike emphasis?

Ubuntu has always used one system typeface, aptly named Ubuntu. That part was easy.

• CSS Fonts Module Level 4 Editor’s Draft Specification
• Chrome Platform Status
• Can I Use entry
• Previous discussions in the W3C to standardize a generic system family.