diff --git a/static/index.html b/static/index.html
index 5ceffb7..f008bb4 100644
--- a/static/index.html
+++ b/static/index.html
@@ -13,18 +13,18 @@
 <a href="https://github.com/fenwick67/mastofeed" class="cta button alt">Fork on Github <img class="link-logo after" src="github-logo.svg" alt="Github Logo" data-reactid="19"></a><br>
 <br><hr><br>
 <form action="javascript:genUrl()">
-	<label>Instance URL:<input required type="text" id="urlin" placeholder="octodon.social"></label><br>
-	<label>Username:<input required type="text" id="usernamein" placeholder="fenwick67"></label><br>
-	<label>Width(px):<input required type="number" id="width" value="400"></label><br>
-	<label>Height(px):<input required type="number" id="height" value="800"></label><br>
-	<label>UI scale (percent):<input required type="number" id="size" value="100"></label><br>
-	<label>theme:
+	<label>Instance URL:<input required type="text" id="urlin" placeholder="octodon.social" oninvalid="this.setCustomValidity('Insert your instance URL. Example: octodon.social')"></label><br>
+	<label>Username:<input required type="text" id="usernamein" placeholder="fenwick67" oninvalid="this.setCustomValidity('Insert your username. Example: fenwick67')"></label><br>
+	<label>Width (px):<input required type="number" id="width" value="400" oninvalid="this.setCustomValidity('Insert width of generated feed. Default: 400')"></label><br>
+	<label>Height (px):<input required type="number" id="height" value="800" oninvalid="this.setCustomValidity('Insert height of generated feed. Default: 800')"></label><br>
+	<label>UI scale (percent):<input required type="number" id="size" value="100" oninvalid="this.setCustomValidity('Insert UI scale. Default: 100')"></label><br>
+	<label>Theme:
 		<select id="theme">
 			<option value="dark">dark</option>
 			<option value="light">light</option>
 		</select>
 	</label><br>
-	<label>Show header?<input id="header" type="checkbox" checked></label><br>
+	<label>Show header?<input id="header" type="checkbox" checked="checked"></label><br>
 	<button value="generate">Generate</button>
 </form>
 <br>
diff --git a/static/stylesheet.css b/static/stylesheet.css
index 40145d7..0eb4d78 100644
--- a/static/stylesheet.css
+++ b/static/stylesheet.css
@@ -30,7 +30,7 @@ a {
 
 label, h3 {
     color: #607ea7;
-    margin-bottom: 26px
+    margin-bottom: 26px;
     font-size: 16px;
     line-height: 24px
 }
@@ -41,7 +41,7 @@ body {
     font-feature-settings: "kern";
     -webkit-text-size-adjust: none;
     -ms-text-size-adjust: none;
-    text-size-adjust: none
+    text-size-adjust: none;
     box-sizing: border-box;
     font-family: Roboto, sans-serif;
     background-color: #1f232b;
@@ -62,7 +62,7 @@ button {
     border: 1px solid #9baec8;
     padding: 3px 15px;
     color: #9baec8;
-    margin-left: 4px
+    margin-left: 4px;
     font-weight: 500;
     border-radius: 4px;
     box-shadow: 0 4px 6px rgba(0, 0, 0, .1)