Created Style tweaks (markdown)

Style-tweaks.md

@@ -0,0 +1,12 @@
+Koreader allows extensive style tweaks within EPUB documents, with ability to edit all CSS element of documents.
+
+![style tweaks](https://user-images.githubusercontent.com/24273478/39957877-7ed7a9f2-55fa-11e8-92c5-b319ca56e808.png)
+![style tweaks](https://user-images.githubusercontent.com/24273478/39957879-8c94564e-55fa-11e8-8957-f5c249b00e11.png)
+![style tweaks](https://user-images.githubusercontent.com/24273478/39957885-aee95c8a-55fa-11e8-8332-d4e304b1611f.png)
+![style tweaks](https://user-images.githubusercontent.com/24273478/39957888-c36fdbc0-55fa-11e8-84b6-d91a865e9c6e.png)
+![](https://user-images.githubusercontent.com/24273478/39957890-d4da97ec-55fa-11e8-838e-3439d994eadf.png)
+![](https://user-images.githubusercontent.com/24273478/39958098-650bde5e-55fe-11e8-847e-a9c05f6c6f91.png)
+![](https://user-images.githubusercontent.com/24273478/39957906-057a7bba-55fb-11e8-9338-7e953fcb0e8b.png)
+![](https://user-images.githubusercontent.com/24273478/39957926-46c6d37a-55fb-11e8-87c6-daa10be2bde7.png)
+
+More info can be found [here.](https://github.com/koreader/koreader/pull/3944)