Fix validator.w3.org warnings and erros (#227)

Author: Rotzbua

_includes/footer.html

@@ -11,7 +11,7 @@
             <div class="row pt-2 mb-4 mb-lg-3 justify-content-between">
                 <div class="col-12 col-lg-4 col-md-12 mb-3">
                     <div class="small mb-4 mb-lg-3"><a href="/{% if site.lang != 'en' %}{{ site.lang }}{% endif %}"><img
-                                src="/assets/branding/logo-full-horizontal-dynamic.svg" width="260px" /></a></div>
+                                src="/assets/branding/logo-full-horizontal-dynamic.svg" width="260" /></a></div>
                     <p class="size-14 color-gray-900 mb-3">{% t footer.description %}</p>
                 </div>
                 <div class="col-0 col-lg-2"></div>

_includes/nav.html

@@ -19,7 +19,7 @@
             <div class="nav-item ml-2 ml-sm-1 text-center">
               <li class="nav-item dropdown mb-0">
                 <button class="nav-link dropdown-toggle" id="navbarDropdown" aria-label="{% t generic.accessibility.lang-menu %}"
-                        role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
+                        data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                   <i class="fa fa-globe size-16 color-gray-900"></i><span
                      class="ml-1 size-16 color-gray-900 weight-600">{{ site.lang | upcase }}</span>
                 </button>
@@ -35,7 +35,7 @@
           <div class="nav-item text-center d-inline-block">
             <div class="nav-item dropdown">
               <button class="nav-link dropdown-toggle" id="navbarDropdown" aria-label="{% t generic.accessibility.lang-menu %}"
-                      role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
+                      data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                 <i class="fa fa-globe size-16 color-gray-900"></i><span
                    class="ml-1 size-16 color-gray-900 weight-600">{{ site.lang | upcase }}</span>
               </button>
@@ -55,7 +55,7 @@
   <div id="navbar-mobile" class="overlay">
     <button class="closebtn" onclick="closeNav()">&times;</button>
       <div class="overlay-header">
-        <img src="/assets/branding/logo-icon.svg" width="80px" height="auto"
+        <img src="/assets/branding/logo-icon.svg" width="80" height="auto"
              alt="{% t generic.accessibility.logo %}" />
       </div>
       <div class="overlay-content">