Fix a semantics issue in HTML.

Syncscroll now uses `data-name` instead of just `name`.
Also, breadcrumb the way with Gherkin.

user/themes/textbook/js/syncscroll.js

-!function(e,n){"function"==typeof define&&define.amd?define(["exports"],n):n("undefined"!=typeof exports?exports:e.syncscroll={})}(this,function(e){var n="Width",t="Height",o="Top",r="Left",f="scroll",i="client",s="EventListener",d="add"+s,c="length",a=Math.round,u={},l=function(){var e,l,p,y,m,h=document.getElementsByClassName("sync"+f);for(m in u)if(u.hasOwnProperty(m))for(e=0;e<u[m][c];e++)u[m][e]["remove"+s](f,u[m][e].syn,0);for(e=0;e<h[c];)if(y=l=0,p=h[e++],m=p.getAttribute("name")){for(p=p[f+"er"]||p;l<(u[m]=u[m]||[])[c];)y|=u[m][l++]==p;y||u[m].push(p),p.eX=p.eY=0,function(e,s){e[d](f,e.syn=function(){var d,l=u[s],p=e[f+r],y=e[f+o],m=p/(e[f+n]-e[i+n]),h=y/(e[f+t]-e[i+t]),v=p!=e.eX,g=y!=e.eY,X=0;for(e.eX=p,e.eY=y;X<l[c];)d=l[X++],d!=e&&(v&&a(d[f+r]-(p=d.eX=a(m*(d[f+n]-d[i+n]))))&&(d[f+r]=p),g&&a(d[f+o]-(y=d.eY=a(h*(d[f+t]-d[i+t]))))&&(d[f+o]=y))},0)}(p,m)}};"complete"==document.readyState?l():window[d]("load",l,0),e.reset=l});
\ No newline at end of file
+// Modified to use 'data-name' attribute instead of 'name'.
+!function(e,n){"function"==typeof define&&define.amd?define(["exports"],n):n("undefined"!=typeof exports?exports:e.syncscroll={})}(this,function(e){var n="Width",t="Height",o="Top",r="Left",f="scroll",i="client",s="EventListener",d="add"+s,c="length",a=Math.round,u={},l=function(){var e,l,p,y,m,h=document.getElementsByClassName("sync"+f);for(m in u)if(u.hasOwnProperty(m))for(e=0;e<u[m][c];e++)u[m][e]["remove"+s](f,u[m][e].syn,0);for(e=0;e<h[c];)if(y=l=0,p=h[e++],m=p.getAttribute("data-name")){for(p=p[f+"er"]||p;l<(u[m]=u[m]||[])[c];)y|=u[m][l++]==p;y||u[m].push(p),p.eX=p.eY=0,function(e,s){e[d](f,e.syn=function(){var d,l=u[s],p=e[f+r],y=e[f+o],m=p/(e[f+n]-e[i+n]),h=y/(e[f+t]-e[i+t]),v=p!=e.eX,g=y!=e.eY,X=0;for(e.eX=p,e.eY=y;X<l[c];)d=l[X++],d!=e&&(v&&a(d[f+r]-(p=d.eX=a(m*(d[f+n]-d[i+n]))))&&(d[f+r]=p),g&&a(d[f+o]-(y=d.eY=a(h*(d[f+t]-d[i+t]))))&&(d[f+o]=y))},0)}(p,m)}};"complete"==document.readyState?l():window[d]("load",l,0),e.reset=l});
\ No newline at end of file

user/themes/textbook/templates/polyglot-columns.html.twig

 {% extends 'partials/base.html.twig' %}
 
+{# Feature: View all translations of a specific course in synchronized columns. #}
 
 {# `page` is irrelevant here #}
 {# use `target_page`, injected by m3-p2 plugin #}
@@ -20,7 +21,7 @@
 {% block body %}
     <div class="claude-columns">
     {% for column in target_page | translations %}
-        <section id="{{ column.slug }}" class="claude-column syncscroll" name="language">
+        <section id="{{ column.slug }}" class="claude-column syncscroll" data-name="language">
             {{ column.content | raw }}
             {#{% include 'partials/contributions-incentive.html.twig' with {page: column} %}#}
         </section>