tweak css

src/app.css

@@ -1,3 +1,24 @@
+:root {
+	--bg-main: #f3f3f3;
+	--bg-bright: white;
+
+	--text-main: #232323;
+	--accent: #351e75;
+}
+
+@media (prefers-color-scheme: dark) {
+	:root {
+		--bg-main: #232323;
+		--bg-bright: black;
+
+		--text-main: #f3f3f3;
+	}
+	
+	#output-graph > div {
+		filter: invert(100%);
+	}
+}
+
 html, body {
 	margin: 0; padding: 0;
 	font-size: 100%;
@@ -5,6 +26,8 @@ html, body {
 body {
 	min-height: 100vh;
 	font-family: Ubuntu, sans-serif;
+	background: var(--bg-main);
+	color: var(--text-main);
 	
 	display: grid;
 	grid-template-columns: 1fr;
@@ -21,15 +44,26 @@ h1 {
 	text-align: center;
 }
 
+textarea, input, #output-graph {
+	background: var(--bg-bright);
+	color: var(--text-main);
+	border: 0.2em dashed var(--accent);
+}
+
 #input-summary {
 	grid-area: summary;
 }
 
 #output-graph {
 	grid-area: graph;
+	overflow-x: scroll;
+	
+	margin: 1em 0;
+	border-left-width: 0;
+	border-right-width: 0;
 }
 
 footer {
 	grid-area: footer;
-	margin: 0.5em;
+	margin: 1em 1em 0.5em 1em;
 }