feat: add theming support

app/src/lib/grid/Cell.svelte

@@ -57,9 +57,20 @@
     overflow: hidden;
   }
   .seperator {
-    background: white;
+    position: relative;
     cursor: ew-resize;
     height: 100%;
-    width: 5px;
+    width: 1px;
+    background: var(--outline);
+  }
+  .seperator::before {
+    content: "";
+    cursor: ew-resize;
+    position: absolute;
+    pointer-events: all;
+    height: 100%;
+    width: 14px;
+    z-index: 2;
+    left: -7px;
   }
 </style>

app/src/lib/grid/Row.svelte

@@ -17,7 +17,7 @@
 
   setContext("sizes", sizes);
 
-  $: cols = $sizes.map((size, i) => `${i > 0 ? "5px " : ""}` + size).join(" ");
+  $: cols = $sizes.map((size, i) => `${i > 0 ? "1px " : ""}` + size).join(" ");
 </script>
 
 <div class="wrapper" style={`grid-template-columns: ${cols};`}>