fix: prevent external CSS from breaking Cal.com embed (#22778)

* fix: added block display to .cal-embed

* fixed the iframe color-scheme to unset and bg transparent

* removed forced CSS

* changes reverted from iframe

* Add comments and remove background transparent as it is still not needed

---------

Co-authored-by: Anik Dhabal Babu <81948346+anikdhabal@users.noreply.github.com>
Co-authored-by: Hariom Balhara <hariombalhara@gmail.com>

packages/embeds/embed-core/src/embed.css

@@ -6,4 +6,9 @@
   min-height: 300px;
   margin: 0 auto;
   width: 100%;
+  /**
+   * Following properties are added to ensure that the embedding page isn't able to affect these properties
+   */
+  display: block !important; /* A website made all iframes' display flex breaking the embed */
+  color-scheme: unset !important; /* A website had explicitly set color-scheme to something for all iframes */
 }