feat: replace completion animation with Gemini-style rotating gradient glow

- Remove bouncing "CRISPY" text animation (dvd-bounce)
- Add rotating conic-gradient border with glow effect
- Colors: purple (#9b59b6), magenta (#e040fb), cyan (#00bcd4), violet (#7c4dff)
- Animation plays once (2.5s) then fades out so students can continue
- Update success colors from green to purple theme:
  - success-color: #9b6dd4
  - success-color-dark: #7c4dff
  - success-color-light: #c9b8e8
- Uses CSS @property for animating conic-gradient angle
- Two layers: blurred glow + crisp border using mask-composite

🤖 Generated with [Claude Code](https://claude.com/claude-code)

src/app.js

@@ -626,11 +626,11 @@ function runCode() {
 		elements.nextBtn.classList.add("success");
 		elements.taskInstruction.classList.add("success-instruction");
 
-		// Show match animation (DVD-style bouncing)
+		// Show match animation (rotating gradient glow)
 		elements.previewWrapper?.classList.add("matched");
 		setTimeout(() => {
 			elements.previewWrapper?.classList.remove("matched");
-		}, 10000);
+		}, 3000);
 
 		updateNavigationButtons();
 		updateProgressDisplay();

src/main.css

@@ -28,9 +28,9 @@
 
 	/* Status colors */
 	--info-color: #7a93fe;
-	--success-color: #58b890;
+	--success-color: #9b6dd4;
-	--success-color-dark: #3d8d6a;
+	--success-color-dark: #7c4dff;
-	--success-color-light: #a3e6c8;
+	--success-color-light: #c9b8e8;
 	--error-color: #cb6e75;
 	--danger-color: #dc3545;
 
@@ -38,7 +38,7 @@
 	--primary-bg-light: rgba(94, 75, 139, 0.05);
 	--primary-bg-medium: rgba(94, 75, 139, 0.1);
 	--primary-bg-instruction: rgba(125, 92, 203, 0.9);
-	--success-bg-light: rgba(88, 184, 144, 0.15);
+	--success-bg-light: rgba(155, 109, 212, 0.15);
 	--modal-bg: rgba(0, 0, 0, 0.5);
 
 	/* Typography */
@@ -596,50 +596,98 @@ kbd {
 	border-radius: var(--border-radius-sm);
 }
 
-/* Success Match Animation */
+/* Success Match Animation - Gemini-style rotating gradient glow */
+@property --gradient-angle {
+	syntax: "<angle>";
+	initial-value: 0deg;
+	inherits: false;
+}
+
 .preview-wrapper.matched {
-	box-shadow: 0 0 0 3px var(--success-color);
+	--glow-size: 3px;
+	--glow-spread: 12px;
 }
 
-.preview-wrapper.matched::after {
+/* Glow layer (blurred background) */
-	content: "CRISPY ٩( ◕‿◕ )۶";
+.preview-wrapper.matched::before {
+	content: "";
 	position: absolute;
-	background: var(--success-color-dark);
+	inset: calc(var(--glow-size) * -1);
-	color: white;
+	border-radius: calc(var(--border-radius-md) + var(--glow-size));
-	padding: var(--spacing-sm) var(--spacing-lg);
+	background: conic-gradient(
-	border-radius: var(--border-radius-lg);
+		from var(--gradient-angle, 0deg),
-	font-weight: bold;
+		#9b59b6,
-	font-size: 1.3rem;
+		#e040fb,
-	animation: dvd-bounce 8s ease-in-out infinite;
+		#00bcd4,
-	z-index: 10;
+		#7c4dff,
-	white-space: nowrap;
+		#9b59b6
+	);
+	z-index: -1;
+	filter: blur(var(--glow-spread));
+	opacity: 0;
+	animation: glow-fade 2.5s ease-out forwards;
 }
 
-@keyframes dvd-bounce {
+/* Border layer (crisp rotating gradient) */
+.preview-wrapper.matched::after {
+	content: "";
+	position: absolute;
+	inset: calc(var(--glow-size) * -1);
+	border-radius: calc(var(--border-radius-md) + var(--glow-size));
+	background: conic-gradient(
+		from var(--gradient-angle, 0deg),
+		#9b59b6,
+		#e040fb,
+		#00bcd4,
+		#7c4dff,
+		#9b59b6
+	);
+	z-index: -1;
+	padding: var(--glow-size);
+	-webkit-mask:
+		linear-gradient(#fff 0 0) content-box,
+		linear-gradient(#fff 0 0);
+	-webkit-mask-composite: xor;
+	mask-composite: exclude;
+	opacity: 0;
+	animation: border-rotate 2.5s ease-out forwards;
+}
+
+@keyframes border-rotate {
 	0% {
-		top: 15%;
+		--gradient-angle: 0deg;
-		left: 15%;
+		opacity: 1;
-		transform: translate(-50%, -50%) scale(1);
 	}
-	25% {
+	70% {
-		top: 75%;
+		opacity: 1;
-		left: 85%;
-		transform: translate(-50%, -50%) scale(1.1);
-	}
-	50% {
-		top: 25%;
-		left: 75%;
-		transform: translate(-50%, -50%) scale(0.95);
-	}
-	75% {
-		top: 70%;
-		left: 20%;
-		transform: translate(-50%, -50%) scale(1.05);
 	}
 	100% {
-		top: 15%;
+		--gradient-angle: -360deg;
-		left: 15%;
+		opacity: 0;
-		transform: translate(-50%, -50%) scale(1);
+	}
+}
+
+@keyframes glow-fade {
+	0% {
+		--gradient-angle: 0deg;
+		opacity: 0;
+		filter: blur(var(--glow-spread));
+	}
+	15% {
+		opacity: 0.7;
+		filter: blur(calc(var(--glow-spread) * 1.5));
+	}
+	50% {
+		opacity: 0.5;
+		filter: blur(var(--glow-spread));
+	}
+	70% {
+		opacity: 0.3;
+	}
+	100% {
+		--gradient-angle: -360deg;
+		opacity: 0;
+		filter: blur(calc(var(--glow-spread) * 0.5));
 	}
 }