feat(embed): Support dark mode (wip)

bskyembed/src/color-mode.ts

@@ -0,0 +1,17 @@
+export function applyTheme(theme: 'light' | 'dark') {
+  document.documentElement.classList.remove('light', 'dark')
+  document.documentElement.classList.add(theme)
+}
+
+export function initColorMode() {
+  applyTheme(
+    window.matchMedia('(prefers-color-scheme: dark)').matches
+      ? 'dark'
+      : 'light',
+  )
+  window
+    .matchMedia('(prefers-color-scheme: dark)')
+    .addEventListener('change', mql => {
+      applyTheme(mql.matches ? 'dark' : 'light')
+    })
+}