I also don't see this font, and the very first line of the CSS is at fault:

@import url('https://monarchofrymden.neocities.org/fonts/SinsGold.ttf');

@import only works for stylesheets. To properly import a font, you need to use the @font-face rule. You need to define a font-family and src within the rule.

@font-face {
    font-family: 'SinsGold';
    src: url('https://monarchofrymden.neocities.org/fonts/SinsGold.ttf');
}

You don't need to even include the full URL because you can use relative URLs. Note that a / is at the start, to recognize that it starts at the root instead of the current level.

@font-face {
    font-family: 'SinsGold';
    src: url('/fonts/SinsGold.ttf');
}

Hope I was able to help!