Import style using <link> tag and replace {DOMAIN} with the current domain:
HTML
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no" />
<link href="/font/fp-glyph/css/fp-glyph.css" rel="stylesheet" />
<link href="https://fonts.googleapis.com/css2?family=Montserrat:wght@300;400;600;700;800&display=swap" rel="stylesheet" />
<link rel="stylesheet" href="{DOMAIN}/tikui.css" />
Pug
meta(name='viewport' content='width=device-width, initial-scale=1, shrink-to-fit=no')
link(href='/font/fp-glyph/css/fp-glyph.css' rel='stylesheet')
link(href='https://fonts.googleapis.com/css2?family=Montserrat:wght@300;400;600;700;800&display=swap' rel='stylesheet')
link(rel='stylesheet' href='{DOMAIN}/tikui.css')
The Style have an Atomic Design organization.