Merge branch '6-add-target-blank' into 'dev'

Resolve "add target blank"

Closes #6

See merge request !7

public/footer.php

 <footer class="bg-dark text-center text-lg-start">
   <!-- Copyright -->
   <div class="text-center p-3" style="background-color: rgba(0, 0, 0, 0.2);">
-    <a rel="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC 4.0</a> |
-    <a href="https://www.tuhh.de/alt/tuhh/startpage.html">Hamburg University of Technology</a> | 
-    <a href="https://www.mat.tuhh.de/index_en.html">Institute of Mathematics</a> | 
-    <a href="https://collaborating.tuhh.de/cfg0846/eams2021">Deployed with GitLab </a> | 
-    <a  href="https://uberspace.de/en/">Hosted on Asteroids </a> | 
-    <a  href="https://draculatheme.com/">CSS by Dracula</a>
+    <a rel="license" href="http://creativecommons.org/licenses/by-nc/4.0/" target="_blank">CC BY-NC 4.0</a> |
+    <a href="https://www.tuhh.de/alt/tuhh/startpage.html" target="_blank">Hamburg University of Technology</a> | 
+    <a href="https://www.mat.tuhh.de/index_en.html" target="_blank">Institute of Mathematics</a> | 
+    <a href="https://collaborating.tuhh.de/cfg0846/eams2021" target="_blank">Deployed with GitLab </a> | 
+    <a href="https://uberspace.de/en/" target="_blank">Hosted on Asteroids </a> | 
+    <a href="https://draculatheme.com/" target="_blank">CSS by Dracula</a>
   </div>
 </footer>
\ No newline at end of file

public/index.php

@@ -38,13 +38,13 @@ $webwork_link="https://webwork.fabian-gabel.de/webwork2/html2xml?&answersSubmitt
     </div>
     <div class="col-9"> 
       <p>
-      On this page, we present a concept for undergraduate mathematics courses that combines shared collaborative whiteboards, zoom breakout sessions and the use of the WeBWorK system in order to get additional hints or to check solutions. We furthermore used this opportunity to let the students compare and rate <a href="https://www.maplesoft.com/digitaled/">Maple T.A.</a> to <a href="https://webwork.maa.org/">WeBWorK</a>.
+      On this page, we present a concept for undergraduate mathematics courses that combines shared collaborative whiteboards, zoom breakout sessions and the use of the WeBWorK system in order to get additional hints or to check solutions. We furthermore used this opportunity to let the students compare and rate <a href="https://www.maplesoft.com/digitaled/" target="_blank">Maple T.A.</a> to <a href="https://webwork.maa.org/" target="_blank">WeBWorK</a>.
       </p>
       <p>
         Each subsection briefly describes the tool itself, its concrete usage in our course and provides a link to an interactive tutorial.
       </p>
       <p>
-        This project was implemented in 3 different exercise groups during the summer term 2021 in the course <a href="https://intranet.tuhh.de/kvvz/kvvz_fenster.php?type=modul&Lang=en&lvid=915"><i>Lineare Algebra (DE)</i></a> at Hamburg University of Technology (TUHH).
+        This project was implemented in 3 different exercise groups during the summer term 2021 in the course <a href="https://intranet.tuhh.de/kvvz/kvvz_fenster.php?type=modul&Lang=en&lvid=915" target="_blank"><i>Lineare Algebra (DE)</i></a> at Hamburg University of Technology (TUHH).
       </p>
     </div>
   </div>
@@ -56,22 +56,22 @@ $webwork_link="https://webwork.fabian-gabel.de/webwork2/html2xml?&answersSubmitt
   <div class="row" >
     <div class="col-4"> 
       <ul>
-        <li> <a href="https://hedgedoc.org/">HedgeDoc</a> is an open-source collaborative <a href="https://www.markdownguide.org/basic-syntax/">markdown</a> editor.</li>
-        <li>If the <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe">iframe</a> on the right does not render correctly, click <a href="<?php echo $hedgedoc_link?>">here</a>.</li>
+        <li> <a href="https://hedgedoc.org/" target="_blank">HedgeDoc</a> is an open-source collaborative <a href="https://www.markdownguide.org/basic-syntax/" target="_blank">markdown</a> editor.</li>
+        <li>If the <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe" target="_blank">iframe</a> on the right does not render correctly, click <a href="<?php echo $hedgedoc_link?>" target="_blank">here</a>.</li>
       </ul>
       <hr style="border:1px solid #ff79c6;">
       <h3>Usage</h3>
       <ul>
         <li>At the beginning of the online exercise session, the tutor shares the link to a HedgeDoc document.</li>
-        <li>On this page, students find links for the whiteboard of each <a href="https://support.zoom.us/hc/en-us/articles/206476093-Enabling-breakout-rooms">breakout room</a>.</li>
+        <li>On this page, students find links for the whiteboard of each <a href="https://support.zoom.us/hc/en-us/articles/206476093-Enabling-breakout-rooms" target="_blank">breakout room</a>.</li>
         <li>Once the breakout session starts, they start working on the exercise problems withing their group.</li>
       </ul>
 
       <h3>Try it yourself</h3>
       <ul>
         <li>You can rapidly set up a document like this.</li>
-        <li>Get started at <a href="https://demo.hedgedoc.org/">demo.hedgedoc.org</a>.
-        <li>Alternatively you can modify <a href="https://writemd.rz.tuhh.de/cC4GDcXSS3GAE-cwe0ZHqw?both">this</a> demo document.</li>
+        <li>Get started at <a href="https://demo.hedgedoc.org/" target="_blank">demo.hedgedoc.org</a>.
+        <li>Alternatively you can modify <a href="https://writemd.rz.tuhh.de/cC4GDcXSS3GAE-cwe0ZHqw?both" target="_blank">this</a> demo document.</li>
       </ul>
 
       <?php include "comment_snippet.html"?>
@@ -87,8 +87,8 @@ $webwork_link="https://webwork.fabian-gabel.de/webwork2/html2xml?&answersSubmitt
   <div class="row" >
     <div class="col-4"> 
       <ul>
-        <li> <a href="https://r7.whiteboardfox.com/">WhiteboardFox</a> provides free, collaborative online whiteboards for real-time editing.</li>
-        <li>If the <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe">iframe</a> on the right does not render correctly, click <a href="<?php echo $whiteboard_link?>">here</a>.</li>
+        <li> <a href="https://r7.whiteboardfox.com/" target="_blank">WhiteboardFox</a> provides <a href="https://r8.whiteboardfox.com/pricing.jsp" target="_blank">free</a>, collaborative online whiteboards for real-time editing.</li>
+        <li>If the <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe" target="_blank">iframe</a> on the right does not render correctly, click <a href="<?php echo $whiteboard_link?>" target="_blank">here</a>.</li>
       </ul>
       <hr style="border:1px solid #ff79c6;">
       <h3>Usage</h3>
@@ -102,8 +102,8 @@ $webwork_link="https://webwork.fabian-gabel.de/webwork2/html2xml?&answersSubmitt
       <h3>Try it yourself</h3>
       <ul>
         <li>You can rapidly set up a whiteboard like this.</li>
-        <li>Get started at <a href="https://r7.whiteboardfox.com/">WhiteboardFox</a> and <i>Start Drawing</i>.
-        <li>Alternatively you can modify <a href="<?php echo $whiteboard_demo?>">this</a> demo document.</a>
+        <li>Get started at <a href="https://r7.whiteboardfox.com/" target="_blank">WhiteboardFox</a> and <i>Start Drawing</i>.
+        <li>Alternatively you can modify <a href="<?php echo $whiteboard_demo?>" target="_blank">this</a> demo document.</a>
       </ul>
 
       <?php include "comment_snippet.html"?>
@@ -121,8 +121,8 @@ $webwork_link="https://webwork.fabian-gabel.de/webwork2/html2xml?&answersSubmitt
   <div class="row" >
     <div class="col-4"> 
       <ul>
-        <li> <a href="https://webwork.maa.org/">WeBWorK</a> is an open-source online homework system used in over 1300 institutions.</li>
-        <li>If the <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe">iframe</a> on the right does not render correctly, click <a href="<?php echo $webwork_link?>">here</a>.</li>
+        <li> <a href="https://webwork.maa.org/" target="_blank">WeBWorK</a> is an open-source online homework system used in over 1300 institutions.</li>
+        <li>If the <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe" target="_blank">iframe</a> on the right does not render correctly, click <a href="<?php echo $webwork_link?>" target="_blank">here</a>.</li>
       </ul>
       <hr style="border:1px solid #ff79c6;">
       <h3>Usage</h3>
@@ -136,9 +136,9 @@ $webwork_link="https://webwork.fabian-gabel.de/webwork2/html2xml?&answersSubmitt
 
       <h3>Try it yourself</h3>
       <ul>
-        <li>You can access the complete course at <a href="https://webwork.fabian-gabel.de/webwork2/la2/">webwork.fabian-gabel.de</a> (German).</li>
+        <li>You can access the complete course at <a href="https://webwork.fabian-gabel.de/webwork2/la2/" target="_blank">webwork.fabian-gabel.de</a> (German).</li>
         <li>Directly proceed to all exercises using the <i>Guest Login</i>.</li>
-        <li>For further information, consult the <a href="https://webwork.maa.org/wiki/WeBWorK_Main_Page">wiki</a>.
+        <li>For further information, consult the <a href="https://webwork.maa.org/wiki/WeBWorK_Main_Page" target="_blank">wiki</a>.
       </ul>
 
       <?php include "comment_snippet.html"?>
@@ -186,7 +186,7 @@ height="400"
   <h1>Contact</h1>
   <hr style="border:1px solid #ff79c6;">
     <ul>
-      <li> <a href="mailto:fabian.gabel@tuhh.de">fabian.gabel@tuhh.de</a> or visit the <a href="https://www.mat.tuhh.de/home/fgabel_en">web page</a></li>
+      <li> <a href="mailto:fabian.gabel@tuhh.de">fabian.gabel@tuhh.de</a> or visit the <a href="https://www.mat.tuhh.de/home/fgabel_en" target="_blank">web page</a></li>
       <li></li>
     </ul>