use EditorConfig

.editorconfig

@@ -0,0 +1,24 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[{*.html,*.css}]
+indent_style = space
+indent_size = 2
+
+[humans.txt]
+indent_style = tab
+indent_size = 2
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.js]
+indent_style = space
+indent_size = 2

docs/index.html

@@ -22,7 +22,7 @@
     <div class="wrap">
       <form action="JavaScript:getCover()">
         <input type="text" id="videoUrl" placeholder="YouTube video url" onchange="getCover()"><!--
-     --><button type="submit">Search</button>
+      --><button type="submit">Search</button>
       </form>
     </div>
   </div>