fix(mobile): Card-Overflow (border-box) + Offcanvas-Menue in Markenfarbe

- .op-split__list: box-sizing border-box -> width:100%+padding ragte 34px
  ueber den Viewport, Kacheln/Suche waren rechts abgeschnitten
- Offcanvas-Menue: Markenblau statt UIkit-Grau, weisse Links,
  gelber Aktiv-/Hover-Akzent, sichtbarer Schliessen-Button

themes/op-dz/assets/css/main.css

@@ -241,6 +241,25 @@ a:hover { color: var(--op-blau-dunkel); }
 }
 .op-navbar .op-logo__img { height: 44px; }
 
+/* Mobiles Offcanvas-Menü im Hausstil (Blau statt UIkit-Default-Grau) */
+.uk-offcanvas-bar { background: var(--op-blau); color: #fff; }
+.uk-offcanvas-bar .uk-nav-primary > li > a {
+  color: #fff; font-weight: 700; text-transform: none;
+}
+.uk-offcanvas-bar .uk-nav-primary > li > a:hover,
+.uk-offcanvas-bar .uk-nav-primary > li > a:focus,
+.uk-offcanvas-bar .uk-nav-primary > li.uk-active > a,
+.uk-offcanvas-bar .uk-nav-primary > li > a[aria-current="page"] {
+  color: var(--op-gelb);
+}
+.uk-offcanvas-bar .uk-nav-sub a { color: rgba(255,255,255,.75); font-weight: 600; }
+.uk-offcanvas-bar .uk-nav-sub a:hover,
+.uk-offcanvas-bar .uk-nav-sub a:focus { color: var(--op-gelb); }
+.uk-offcanvas-bar .uk-nav-parent-icon > .uk-parent > a .uk-nav-parent-icon,
+.uk-offcanvas-bar .uk-close,
+.uk-offcanvas-bar .uk-offcanvas-close { color: #fff; }
+.uk-offcanvas-bar .uk-offcanvas-close:hover { color: var(--op-gelb); }
+
 /* =========================================================================
    6. TOPBAR
    ========================================================================= */
@@ -506,7 +525,7 @@ a:hover { color: var(--op-blau-dunkel); }
 
 /* --- 15a. Split-View (Karte + Liste), Vorbild map.offener-prozess.de --- */
 .op-split { display: flex; align-items: flex-start; }
-.op-split__list { width: 50%; padding: 2rem clamp(1rem, 3vw, 2.5rem); }
+.op-split__list { box-sizing: border-box; width: 50%; padding: 2rem clamp(1rem, 3vw, 2.5rem); }
 .op-split__map {
   width: 50%;
   position: sticky;