Make it suitable for use with Stylish, without external imports (other than Google Fonts)

Roam-tufte.css

@-moz-document domain("roamresearch.com") {
  @import url('https://fonts.googleapis.com/css2?family=Merriweather:ital,wght@0,400;0,700;1,400;1,700&family=Playfair+Display:ital,wght@0,400;0,700;1,400;1,700&family=Source+Code+Pro&display=swap');

  :root {
      --text-size-xs: 0.69rem;
      --text-size-sm: 1rem;
      --text-size-md: 1rem;
      --text-size-2xl: 1.7rem;
      --text-size-3xl: 2.2rem;
      --text-size-4xl: 3.2rem;
      --border-color: #dddddd;
      --link-color: #c6262e;


      --header-font: "Playfair Display", serif;
      --body-font: "Merriweather", serif;
      --monospace-font: "Source Code Pro", monospace;

      --header-color: #f0e8db;
      --header-text-color: #111;

      --text-color: #111;
      --background-color: #fffdfa;

      --right-sidebar-background-color: #fffdfa;
      --right-sidebar-border-size: 1px;

      --tag-background-color: #f0e8db;
      --tag-background-hover-color: #f0e8db;
      --tag-hover-color: #e82c2e;
      --tag-color: #555;

      --sidebar-color: #fffdfa;
      --sidebar-text-color: #111;
      --sidebar-text-hover-color: #F2B230;
  }

  html {
      font-size: 14px
  }

  @media(min-width:700px) {
      html {
          font-size: 16px
      }
  }

  body,
  div,
  p,
  textarea {
      font-family: var(--body-font)!important;
      color: var(--text-color)
  }

  h1,
  h2,
  h3,
  h4,
  h5,
  h6,
  .rm-level1 *,
  .rm-level2 *,
  .rm-level3 *,
  .rm-heading-level-1 > .rm-block__self .rm-block__input,
  .rm-heading-level-2 > .rm-block__self .rm-block__input,
  .rm-heading-level-3 > .rm-block__self .rm-block__input,
  textarea.rm-title-textarea {
      font-family: var(--header-font)!important
  }

  .CodeMirror .CodeMirror-code pre,
  .CodeMirror-linenumber {
      font-family: var(--monospace-font)!important;
      font-size: var(--text-size-sm)
  }

  .rm-page-ref,
  .rm-page-ref-tag {
      font-weight: 700
  }

  body,
  div,
  p,
  textarea {
      line-height: unset;
      letter-spacing: 0
  }

  p,
  .roam-block,
  textarea.rm-block-input {
      font-size: var(--text-size-md);
      line-height: 1.65
  }

  .rm-block > .rm-block__self > .controls {
      margin-top: 2px
  }

  h1,
  .rm-level1 span,
  .sidebar-content h1.level2,
  .rm-title-editing-display textarea,
  .rm-heading-level-1 > .rm-block__self .rm-block__input,
  h1 textarea {
      margin-top: 0;
      font-size: var(--text-size-4xl)!important;
      line-height: 1.25
  }

  .rm-heading-level-1 > .rm-block__self .rm-block__input {
      margin-top: 2rem;
      margin-bottom: 1.5rem
  }

  .rm-heading-level-1 > rm-block__self textarea.rm-block__input {
      margin-bottom: 1.7rem;
      padding: 6px 0
  }

  .rm-heading-level-1 > .rm-block__self > .controls {
      margin-top: calc(2rem + 24px)
  }

  h2,
  .rm-level2 span,
  .rm-heading-level-2 > .rm-block__self .rm-block__input,
  h2 textarea {
      font-size: var(--text-size-3xl)!important;
      font-style: italic;
      line-height: 1.25;
      margin-top: 2.1rem;
      margin-bottom: 1.4rem
  }

  .rm-heading-level-2 > .rm-block__self textarea.rm-block__input {
      margin-bottom: 1.6rem;
      padding: 4px 0
  }

  .rm-heading-level-2 > .rm-block__self > .controls {
      margin-top: calc(2rem + 16px)
  }

  h3,
  .rm-level3 span,
  .rm-heading-level-3 > .rm-block__self .rm-block__input {
      font-size: var(--text-size-2xl)!important;
      color: var(--text-color);
      font-style: italic;
      line-height: 1.25;
      margin-top: 2rem;
      margin-bottom: 1.4rem
  }

  .rm-heading-level-3 > .rm-block__self textarea.rm-block__input {
      margin-bottom: 1.8rem;
      padding: 5px 0 4px
  }

  .rm-heading-level-3 > .rm-block__self > .controls {
      margin-top: calc(2rem + 12px)
  }

  caption,
  .text-caption {
      font-size: var(--text-size-sm)!important
  }

  small,
  .text-small {
      font-size: var(--text-size-xs)!important
  }

  .rm-zoom.zoom-mentions-view {
      font-size: unset
  }

  .sidebar-content .window-headers > div {
      font-size: var(--text-size-md)!important
  }

  .sidebar-content div[style*="padding-bottom: 8px"] > div[style*="margin-top: -8px"] {
      margin-top: 8px!important
  }

  .rm-page-ref__brackets {
      display: none
  }

  a {
      color: var(--link-color);
      font-weight: 700
  }

  a:hover {
      color: var(--link-color);
      text-decoration: underline
  }

  div.rm-block-text,
  textarea.rm-block-text {
      margin-top: -.25rem
  }

  .check-container {
      top: -.1rem!important;
      margin-right: 4px
  }

  .checkmark {
      height: 1rem;
      width: 1rem
  }

  .check-container .checkmark::after {
      left: 4.5px;
      top: .5px
  }

  .roam-table th,
  .roam-table td,
  .roam-table tr {
      border: 0;
      border-bottom: 1px solid var(--border-color)
  }

  .roam-table table > *:first-child > tr:first-of-type,
  .roam-table table.dont-focus-block tr:nth-of-type(2) {
      border-top: 2px solid var(--text-color);
      border-bottom: 0
  }

  .roam-table table tbody > tr:last-of-type {
      border-bottom: 2px solid var(--text-color)
  }

  .roam-table span[style*="background-color: rgb(14, 90, 138);"] {
      background-color: unset!important
  }

  div#right-sidebar {
      background-color: var(--right-sidebar-background-color);
      padding-top: 45px
  }

  div.roam-center,
  div.roam-body-main {
      background-color: var(--background-color)
  }

  div#right-sidebar {
      border-left: var(--right-sidebar-border-size) solid var(--border-color)
  }

  .roam-sidebar-container {
      border-right: var(--right-sidebar-border-size) solid var(--border-color)
  }

  #right-sidebar .level2 > a {
      color: var(--text-color)
  }

  .rm-reference-item {
      background-color: var(--background-color)
  }

  #right-sidebar .rm-reference-item {
      background-color: var(--right-sidebar-background-color)
  }

  #right-sidebar .bp3-button:before,
  #right-sidebar .bp3-button .bp3-icon {
      color: var(--sidebar-text-color)
  }

  .rm-page-ref-tag,
  .rm-page-ref {
      color: var(--tag-color)!important;
      background-color: var(--tag-background-color);
      padding: 2px 4px;
      border-radius: 5px;
      transition: color, background .35s ease-in-out 0s
  }

  .rm-page-ref-tag:hover,
  .rm-page-ref:hover {
      color: var(--tag-hover-color)!important;
      background-color: var(--tag-background-hover-color)!important;
      text-decoration: none
  }

  div[style="color: rgb(206, 217, 224);"],
  strong[style="color: rgb(206, 217, 224);"] {
      color: var(--text-color)!important
  }

  #roam-sidebar-logo {
      display: none
  }

  .roam-body .roam-app .roam-sidebar-container {
      background-color: var(--sidebar-color)
  }

  .roam-sidebar-container .rm-db-title-container .rm-db-title,
  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .log-button,
  .starred-pages-wrapper > div > span,
  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .starred-pages-wrapper .starred-pages .page,
  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .rm-db-title .expand-icon {
      color: var(--sidebar-text-color)
  }

  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .starred-pages-wrapper .starred-pages .page,
  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .starred-pages-wrapper .starred-pages .page:hover {
      font-weight: 400
  }

  div.starred-pages-wrapper > div:first-child {
      background-color: var(--border-color)!important
  }

  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .starred-pages-wrapper .starred-pages .page:hover,
  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .log-button:hover,
  .roam-body .roam-app .roam-sidebar-container .roam-sidebar-content .top-row:hover {
      background-color: unset;
      color: var(--sidebar-text-hover-color)!important
  }

  div.roam-sidebar-container[style*="top: 0px;"] {
      padding-top: 45px
  }

  div.roam-sidebar-container[style*="top: 0px;"] span.bp3-icon-menu-closed {
      opacity: 1!important
  }

  .log-button > div {
      color: inherit
  }

  div.roam-sidebar-container span.bp3-icon-menu-closed::before,
  .rm-topbar .bp3-button[class*=bp3-icon-]::before,
  .rm-topbar .bp3-button .bp3-icon {
      color: var(--header-text-color)
  }

  #find-or-create-input {
      background-color: var(--background-color)
  }

  .rm-find-or-create-wrapper .bp3-popover .bp3-menu {
      background-color: var(--background-color)
  }

  .rm-find-or-create-wrapper .bp3-popover .bp3-menu div[style*=background-color] {
      background-color: var(--header-color)!important
  }

  .rm-ref-page-view-title > a {
      color: var(--tag-color);
      background-color: var(--tag-background-color);
      font-size: var(--text-size-md)
  }

  .rm-query .rm-query-title {
      background-color: var(--header-color);
      color: var(--header-text-color);
      font-family: var(--monospace-font)!important;
      font-size: var(--text-size-sm)
  }

  .sidebar-content > div > div {
      border-bottom: 1px solid var(--border-color)!important
  }

  .block-border-left {
      border-left: 1px solid var(--border-color)
  }

  .roam-log-container .roam-log-page {
      border-top: 1px solid var(--border-color)
  }

  .roam-log-container .roam-log-page:first-child {
      border-top: 0
  }

  .rm-embed-container {
      background-color: var(--background-color)
  }

  span[style="color: red;"] {
      color: var(--link-color)!important
  }

  .rm-query {
      border-color: var(--border-color)
  }

  .rm-multibar {
      border-color: var(--border-color)
  }

  .rm-multibar:hover {
      border-color: var(--border-color)
  }

  .check-container input:checked ~ .checkmark {
      background-color: var(--tag-color)
  }

  .intercom-lightweight-app {
      display: none
  }

  .CodeMirror {
      border: 1px solid var(--border-color);
      background-color: var(--background-color)
  }

  .CodeMirror-gutters {
      background-color: var(--header-color)
  }

  .CodeMirror-linenumber {
      color: var(--tag-color)
  }

  .rm-sidebar-outline .rm-title-display {
      padding-top: 0;
      padding-bottom: 8px
  }

  #rm-mobile-bar {
      z-index: 6
  }

  .roam-body-main {
      position: relative
  }

  .rm-topbar {
      position: fixed;
      left: 0;
      right: 0;
      top: 0;
      z-index: 9999;
      background-color: var(--header-color)
  }

  .bp3-tooltip .bp3-popover-arrow-fill {
      fill: var(--background-color)
  }

  .bp3-tooltip .bp3-popover-content {
      background-color: var(--background-color);
      color: var(--text-color)
  }

  .bp3-tooltip .bp3-popover-content a {
      color: var(--text-color)
  }

  @media(min-width:700px) {
      div.roam-center > div {
          padding-right: 0!important
      }

      #roam-right-sidebar-content {
          padding-left: 42px
      }

      div.roam-sidebar-container[style*=box-shadow] {
          bottom: 0!important;
          box-shadow: unset!important
      }

      .sidebar-content > div > div {
          padding: 16px 0
      }

      .rm-title-display,
      .roam-body-main .rm-title-editing-display {
          margin-top: 50px
      }

      .roam-article .roam-log-page:not(:first-child) .rm-title-display {
          margin-top: 0
      }

      #right-sidebar .rm-sidebar-outline .rm-title-editing-display {
          margin-top: -56px;
          margin-bottom: 8px
      }

      .rm-title-display,
      .roam-body-main .rm-title-editing-display {
          padding-top: 8px
      }

      .check-container .checkmark::after {
          left: 5px;
          top: 1.5px
      }
  }

  .rm-help-popup {
      z-index: 9999
  }

  .rm-help-popup .rm-help-popup__drag-handle {
      background-color: var(--background-color);
      border-color: var(--border-color)
  }

  .jsPanel-hdr,
  #jsPanelDNP-min {
      border-radius: 5px
  }

  .jsPanel-headerbar {
      border-top-left-radius: 5px;
      border-top-right-radius: 5px
  }

  div[data-tippy-root] {
      background-color: var(--background-color)
  }
}