Add .editorconfig for consistent formatting and apply it

.editorconfig

@@ -0,0 +1,19 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+charset = utf-8
+
+[*.html]
+indent_size = 2
+trim_trailing_whitespace = true
+
+[*.css]
+indent_size = 2
+trim_trailing_whitespace = true
+
+[*.md]
+indent_size = 2
+trim_trailing_whitespace = false