fix(conv): scroll btn; css clean up

frontend/src/index.css

@@ -2,6 +2,16 @@
 @tailwind components;
 @tailwind utilities;
 
+:root {
+  --viewport-height: 100vh;
+}
+
+@supports (height: 100dvh) {
+  :root {
+      --viewport-height: 100dvh; /* Use dvh where supported */
+  }
+}
+
 body.dark {
   background-color: #202124; /* raisin-black */
 }
@@ -63,20 +73,19 @@ html {
 
 body {
   margin: 0;
-  min-height: 100vh;
+  min-height: var(--viewport-height);
   overflow-x: hidden;
   font-family: 'Inter', sans-serif;
 }
 /*
-Avoid changing height in mobile browsers
+Avoid over-scrolling in mobile browsers
 */
 @media only screen and (max-width: 500px) {
   body,
   html {
-    height: 100%;
+    min-height: var(--viewport-height);
     position: fixed;
     width: 100%;
-    overflow-y: none;
   }
 }
 /**