Add theme support, light theme, and edgeless light

sass/includes/channel-page.sass

@@ -1,78 +0,0 @@
-@use "colors.sass" as c
-@use "video-list-item.sass" as *
-@use "_dimensions.sass" as dimensions
-
-.channel-page
-  padding: 40px 20px 20px
-  max-width: 900px
-  margin: 0 auto
-
-.banner
-  display: flex
-
-.banner-image
-  width: 100%
-  height: auto
-  border-radius: 8px
-  align-self: flex-start
-
-.channel-data
-  background-color: c.$bg-darker
-  padding: 24px
-  margin: 12px 0px 24px
-  border-radius: 8px
-
-  .info
-    display: flex
-    flex-wrap: wrap
-
-    +dimensions.thin
-      display: block
-
-    .thumbnail-image
-      $size: 120px
-
-      width: $size
-      height: $size
-      border-radius: 50%
-      margin-right: 24px
-
-    .about
-      flex: 1
-      margin-top: 10px
-
-      .name
-        font-size: 30px
-        font-weight: normal
-        color: c.$fg-bright
-        margin: 0
-
-      .subscribers
-        color: c.$fg-main
-        font-size: 18px
-
-    .subscribe-form
-      margin-top: 24px
-
-      .subscribe-button
-        $padding: 14px
-
-        padding: $padding - 2px $padding $padding
-        line-height: 1
-        border-radius: 8px
-        font-size: 22px
-        background-color: c.$power-deep
-        border: none
-
-  .description
-    margin-top: 16px
-    overflow-wrap: break-word
-
-.channel-video
-  @include channel-video
-
-.about-description // class provided by youtube
-  pre
-    font-size: inherit
-    font-family: inherit
-    white-space: pre-wrap