Add missing CSS files.

www/css/adelie.desktop.css

+@media screen and ( min-width: 761px )  {
+    body > header { min-width: 760px; }
+    body > div { min-width: 760px; }
+    body > footer { min-width: 760px; }
+    div.herobox {
+        background-image: linear-gradient(to bottom, rgba(255,255,255,0.7) 0%,rgba(255,255,255,0.7) 100%), url("/web/20200930042041im_/https://static.adelielinux.org/img/backdrop1.jpeg");
+    }
+}

www/css/adelie.mobile.css

+@media screen and ( max-width: 760px )  {
+  /* linearization for grid module */
+  .linearize-level-1,
+  .linearize-level-1 > [class*="ym-g"] {
+    display: block;
+    float: none;
+    padding: 0;
+    margin: 0;
+    width: 100% !important;
+  }
+  /* reset defined gutter values */
+  .linearize-level-1 > [class*="ym-g"] > [class*="ym-gbox"] {
+    overflow: hidden; /* optional for containing floats */
+    padding: 0;
+    margin: 0;
+  }
+}