Create back-to-top button using HTML and CSS

Fixes OtacilioN#790 

Created a back to top button code using HTML and CSS.
Also added code for floating back to top button.

Hope this solves the issue.

Looking forward for merging this PR.

back-to-top button using HTML and CSS

@@ -0,0 +1,29 @@
+<!-- HTML File -->
+<a href="#">Scroll To Top</a>
+
+/* CSS File */
+/* Basic css code for smooth scrolling */
+:root { scroll-behavior: smooth; }
+/* For floating back to top button */
+.stt {
+  position: fixed;
+  right: 1rem;
+  bottom: 1rem;
+  width: 3rem;
+  height: 3rem;
+  border-radius: 50%;
+  background: rgb(128, 128, 255) url("data:image/svg+xml;utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 384 512'%3E%3Cpath fill='currentColor' d='M352 352c-8.188 0-16.38-3.125-22.62-9.375L192 205.3l-137.4 137.4c-12.5 12.5-32.75 12.5-45.25 0s-12.5-32.75 0-45.25l160-160c12.5-12.5 32.75-12.5 45.25 0l160 160c12.5 12.5 12.5 32.75 0 45.25C368.4 348.9 360.2 352 352 352z'%3E%3C/path%3E%3C/svg%3E") center no-repeat;
+  box-shadow: 0 0.25rem 0.5rem 0 gray;
+  opacity: 0.7;
+}
+.stt:hover {
+  opacity: 0.8;
+}
+.stt:focus {
+  opacity: 0.9;
+}
+.stt:active {
+  opacity: 1;
+}
+/* After adding this link you have to update the HTML link by the following code
+<a href='#' class="stt" title="scroll to top"></a> */