diff --git a/samples/calc-02/index.css b/samples/calc-02/index.css
index 721d107..9509098 100644
--- a/samples/calc-02/index.css
+++ b/samples/calc-02/index.css
@@ -159,26 +159,26 @@ body {
 .display-buttons-grid {
 	display: grid;
 	grid-template-columns: repeat(4, minmax(0, 1fr));
-	grid-template-rows: repeat(2, auto);
 	gap: 8px;
 	align-content: start;
 	align-items: stretch;
-	grid-auto-flow: row;
-	grid-auto-rows: auto;
 }
 
 .display-button {
-	box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08), 0 3px 0 rgba(0, 0, 0, 0.34);
-	background-clip: padding-box;
-	background: linear-gradient(180deg, #3a414c, #252b34);
-	color: #e8edf3;
-	border-color: rgba(255, 255, 255, 0.05);
+	background: linear-gradient(180deg, var(--btnTop), var(--btnBottom));
+	color: #eef2f7;
+	box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.18), 0 3px 0 rgba(0, 0, 0, 0.28);
 }
 
 .display-button-offset {
 	grid-column-start: 2;
 }
 
+.display-button-spacer {
+	opacity: 0;
+	pointer-events: none;
+}
+
 .mode-menu {
 	position: fixed;
 	z-index: 20;
@@ -206,14 +206,6 @@ body {
 	color: #eef2f7;
 }
 
-.display-button:nth-child(6) {
-	background: linear-gradient(180deg, #343b46, #20262e);
-}
-
-.display-button:nth-child(7) {
-	background: linear-gradient(180deg, #343b46, #20262e);
-}
-
 .keypad-panel {
 	grid-area: keypad;
 	padding: 10px;
@@ -427,6 +419,10 @@ button:active {
 			"trigo";
 	}
 
+	.display-buttons-grid {
+		grid-template-columns: repeat(4, minmax(0, 1fr));
+	}
+
 	.keypad-grid {
 		grid-template-rows: repeat(5, minmax(42px, 1fr));
 	}
diff --git a/samples/calc-02/index.html b/samples/calc-02/index.html
index 2786cab..658338c 100644
--- a/samples/calc-02/index.html
+++ b/samples/calc-02/index.html
@@ -24,13 +24,16 @@
 			</div>
 
 			<div class="display-buttons-panel">
-				<button id="modeButton" class="display-button">Mode</button>
-				<button id="pasteButton" class="display-button">⎘</button>
-				<button id="upButton" class="display-button">↑</button>
-				<button id="constButton" class="display-button">π</button>
-				<button id="leftButton" class="display-button display-button-offset">←</button>
-				<button id="downButton" class="display-button">↓</button>
-				<button id="rightButton" class="display-button">→</button>
+				<div class="display-buttons-grid">
+					<button id="modeButton" class="display-button key-default">Mode</button>
+					<button id="pasteButton" class="display-button key-default">⎘</button>
+					<button id="upButton" class="display-button key-default">↑</button>
+					<button id="constButton" class="display-button key-default">π</button>
+					<button id="leftButton" class="display-button key-default display-button-offset">←</button>
+					<button id="downButton" class="display-button key-default">↓</button>
+					<button id="rightButton" class="display-button key-default">→</button>
+					<div class="display-button-spacer"></div>
+				</div>
 			</div>
 			
 			<div class="keypad-panel">