replaced back with 'search' button

web/app/templates/abstracts.html

         <!-- The following total reading time is based on the calculation of approx. 43,647,513 words in all the documents divided by 200 as the average reading speed of 200 wpm -->
         <p class="operations">↪ a <span id="time"></span> minute read out of 218238 minutes reading time</p>
       </span>
-      <a href="{{ url_for('main.index') }}" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+      <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
     </div>
   </div>
 

web/app/templates/compare.html

     <span class="operations">↝ new display of random records from the dataset;</span>
   </span>
   <button id="notes-operations" onclick="hideShowInfo()">?</button>
-  <a href="{{ url_for('main.index') }}" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+  <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
 </div>
 
 <div class="compare mt-5">

web/app/templates/conversations-overview.html

 <div class="text">
     <button id="notes-operations" onclick="hideShowInfo()">?</button>
-    <a href="/contents/" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+    <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
     
 {% extends "base.html" %}
 

web/app/templates/data.html

 
 {% block content %}
 
-<a href="{{ url_for('main.index') }}" class="h1 text-left" title="back to index"> ⇽ </a>
+<a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
 
 <h1 class="h1 text-center"> There are a total of {{ total_number }} patents.</h1>
 

web/app/templates/hidden.html

 <div class="themes">
-    <a href="/contents/" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+    <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
+
     
 {% extends "base.html" %}
     

web/app/templates/images.html

     <span class="operations">↝ remove a random image from page;</span>
   </span>
   <button id="notes-operations" onclick="hideShowInfo()">?</button>
-  <a href="{{ url_for('main.index') }}" class="arrow-back h1 text-left contrast" style="color: var(--color-lightyellow) !important;" title="back to index"> ⇽ </a>
+  <a href="{{ url_for('main.index') }}" class="search-back text-left" style="color: var(--color-lightyellow) !important;" title="back to search">search</a>
 </div>
 
 <div class="row">

web/app/templates/making-overview.html

 <div class="text">
     <button id="notes-operations" onclick="hideShowInfo()">?</button>
-    <a href="/contents/" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+    <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
     
 {% extends "base.html" %}
 

web/app/templates/record.html

     <span class="operations">↝ new display of a random record from the dataset;</span>
   </span>
   <button id="notes-operations" onclick="hideShowInfo()">?</button>
-  <a href="{{ url_for('main.index') }}" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+  <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
 </div>
 
   {% for result in results %}

web/app/templates/search.html

 
 <div class="row">
   <div class="col m-5">
-    <a href="{{ url_for('main.index') }}" class="h1 text-left"> ⇽ </a>
+    <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
     <p class="h1 text-center">a timeline of inventions</p>
     <p class="mt-2 text-center">{{ num_found }} patents found out of {{ total_number }}</p>
   </div>

web/app/templates/text.html

 <div class="text">
     <button id="notes-operations" onclick="hideShowInfo()">?</button>
-    <a href="/contents/" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+    <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
     
 {% extends "base.html" %}
 

web/app/templates/titles.html

     <span class="operations">↝ remove a random title from page;</span>
   </span>
   <button id="notes-operations" onclick="hideShowInfo()">?</button>
-  <a href="{{ url_for('main.index') }}" class="arrow-back h1 text-left" title="back to index"> ⇽ </a>
+  <a href="{{ url_for('main.index') }}" class="search-back text-left" title="back to search">search</a>
 </div>
 
 <div class="row">