Change the fonts in Notion via Stylus

style.css

/* ==UserStyle==
@name         notion-custom-fonts
@version      20240503.19.42
@namespace    https://userstyles.world/user/aquariuslt
@description  customize your notion fonts (cjk + latin)
@author       aquariuslt
@license      MIT
==/UserStyle== */
@-moz-document domain("notion.so") {
    /* define cjk font here */
    @font-face {
        font-family: 'CustomFontCJK';
        src: local('Noto Serif SC');
        unicode-range: U+4E00-9FFF;
    }

    @font-face {
        font-family: 'CustomFontCJK-Bold';
        src: local('Noto Serif SC SemiBold');
        unicode-range: U+4E00-9FFF;
    }

    /* define latin/us font here */
    @font-face {
        font-family: 'CustomFontLatin';
        src: local('Outfit-Thin_ExtraLight');
        unicode-range: U+0000-007F, U+0080-00FF;
    }

    /* define code/monospace font here */
    @font-face {
        font-family: 'CustomFontCode';
        src: local('Iosevka'), local("Consolas");
        unicode-range: U+0000-007F, U+0080-00FF;
    }


    /* title in Notion */
    #notion-app > * h1 {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif;
        font-weight: 600;
    }


    /* h1 in Notion */
    #notion-app > * h2 {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;

        color: #364e96;
        padding: 0.5em 0;
        border-top: solid 3px #364e96;
        border-bottom: solid 3px #364e96;
    }

    /* h2 in Notion */
    #notion-app > * h3 {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;

        padding: 0.4em 0.5em;
        color: #494949;
        background: #f4f4f4;
        border-left: solid 5px #7db4e6;
        border-bottom: solid 3px #d7d7d7;
    }

    /* h3 in Notion */
    #notion-app > * h4 {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;

        background: linear-gradient(transparent 70%, #a7d6ff 70%);
    }


    /* normal text block */
    #notion-app > * .notion-text-block > * div.notranslate {
        font-family: 'CustomFontCJK', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
        font-weight: normal;
    }

    /* quote block */
    #notion-app > * .notion-quote-block > * div.notranslate {
        font-family: 'CustomFontCJK', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
        font-weight: normal;
    }

    /* code block */
    #notion-app > * .notion-code-block > * div.notranslate {
        font-family: 'CustomFontCode', 'CustomFontLatin', monospaced !important;
    }


    /* mention */
    #notion-app > * .notion-text-mention-token,
    #notion-app > * .notion-external_object_instance-block {
        font-family: 'CustomFontCJK', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
        font-weight: normal;
    }

    /* list-item */
    #notion-app > * .notion-page-block > * div.notranslate,
    #notion-app > * .notion-collection-item > * div,
    #notion-app > * .notion-collection_view_page-block > * div.notranslate,
    #notion-app > * .notion-bulleted_list-block > * div.notranslate,
    #notion-app > * .notion-numbered_list-block > * div.notranslate {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif;
    }


    /* page property */
    /* page placeholder */
    #notion-app > * div[aria-label="Page properties"] {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
    }

    /* template button */
    #notion-app > * div[role="button"] {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
    }


    /* breadcrumbs */
    /* sidebar */
    .notion-sidebar-container,
    .notion-topbar {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
        font-weight: 500;
    }


    /* inbox */
    /* search modal */
    .notion-scroller > div,
    .notion-search-menu > * div {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
    }



    /* account settings modal */
    .notion-space-settings {
        font-family: 'CustomFontCJK-Bold', 'CustomFontLatin', ui-sans-serif, sans-serif !important;
    }
}