web: remove broken android navigation bar coloring

cuz it doesn't work

src/front/cobalt.css

@@ -50,7 +50,6 @@ body {
     height: calc(100% + env(safe-area-inset-top) / 2);
     margin: 0;
     background: var(--background);
-    background-color: var(--background);
     color: var(--accent);
     -webkit-tap-highlight-color: var(--transparent);
     font-family: var(--font-mono);

src/front/cobalt.js

@@ -168,7 +168,6 @@ const changeStatusBarColor = () => {
     }
 
     document.querySelector('meta[name="theme-color"]').setAttribute('content', colors[state]);
-    document.querySelector('meta[name="background-color"]').setAttribute('content', colors[state]);
 }
 const detectColorScheme = () => {
     document.documentElement.setAttribute("data-theme", preferredColorScheme());