feat(legal): add legal notice error handling

The legal notice view now shows an error box if the legal notice could
not be loaded.

src/styles/common.css

@@ -92,4 +92,12 @@ input {
 /* Temporary until a custom tap highlight is implemented. */
 * {
     -webkit-tap-highlight-color: transparent;
-}
+}
+
+.error {
+    background-color: var(--color-negative-bg);
+    border: 1px solid var(--color-negative-border);
+    padding: 1em 2em;
+    border-radius: 1.2em;
+    color: var(--white);
+}

src/styles/variables/colors.css

@@ -84,6 +84,9 @@ body {
     --light-hover:          var(--light-d-2);
 
     --invert: invert(0);
+
+    --color-negative-bg:     oklch(59% 0.22706 29.244);
+    --color-negative-border: oklch(51% 0.22706 29.244);
 }
 
 @media (prefers-color-scheme: dark) {