Tailwind CSS variables based on light/dark mode

<button class="some-section">
</button>

<style lang="scss">
  :root {
    --button-bg: some-color;
  }

  @media (prefers-color-scheme: dark) {
    :root {
      --button-bg: other color;
    }
  }

  .some-section {
    background-color: var(--button-bg);
  }
</style>

<script lang="ts">
  let theme: "light" | "dark" : "auto";
  const isPageDark = () => document.body.getAttribute("dark") !== null;
  let themeCurrent: "light" | "dark" = isPageDark() ? "dark" : "light";

  $: if (theme === "auto") {
    themeCurrent = isPageDark() ? "dark" : "light";
  }
  new MutationObserver(() => {
    if (theme === "auto") {
      themeCurrent = isPageDark() ? "dark" : "light";
    }
  }).observe(document.body, { attribtes: true, attributeFilter: ["dark"] })
</script>

<button on:click={() => theme = "light"}Light theme</button>
<button on:click={() => theme = "dark"}>Dark theme</button>
<button on:click={() => theme = "auto"}>Auto</button>

<main data-theme={themeCurrent}>
</main>

<style lang="scss">
  [data-theme="light"] {
    --bg: some-color;
  }

  [data-theme="dark"] {
    --bg: some-other-color;
  }

  main {
    background-color: var(--bg);
  }
</style>