diff --git a/index.html b/index.html
index 58ee2db..993b2ce 100644
--- a/index.html
+++ b/index.html
@@ -138,5 +138,6 @@
 	<script src="js/greeter-date-message.js"></script>
 	<script src="js/search-engine-settings.js"></script>
 	<script src="js/search-query-send.js"></script>
+	<script src="js/theme-engine.js"></script>
 </body>
 </html>
\ No newline at end of file
diff --git a/js/theme-engine.js b/js/theme-engine.js
new file mode 100644
index 0000000..dfc5bee
--- /dev/null
+++ b/js/theme-engine.js
@@ -0,0 +1,210 @@
+var localStorage = window.localStorage;
+
+var backgroundTextBox = document.getElementById('backgroundSet');
+var backgroundOpacityTextBox = document.getElementById('backgroundOpacitySet');
+var foregroundTextBox = document.getElementById('foregroundSet');
+var foregroundOpacityTextBox = document.getElementById('foregroundOpacitySet');
+
+var blurTextBox = document.getElementById('blurSet');
+
+var applyTheme = document.getElementById('themeEngineAsDefault');
+var resetTheme = document.getElementById('themeEngineReset');
+
+// Save CSS color variables default in localStorage
+// Will only save if you visit the webpage for the very first time
+const saveDefaultCSS = () => {
+
+	var origBaseBG = localStorage.getItem('origBaseBG');
+	var origBaseColor = localStorage.getItem('origBaseColor');
+	var origBlurStrength = localStorage.getItem('origBlurStrength');
+	
+	if ((origBaseBG === null) || (origBaseColor === null) || (origBlurStrength) === null) {
+
+		localStorage.setItem(
+			'origBaseBG',
+			window.getComputedStyle(document.documentElement).getPropertyValue('--base-bg')
+		);
+		localStorage.setItem(
+			'origBaseColor',
+			window.getComputedStyle(document.documentElement).getPropertyValue('--base-color')
+		);
+		localStorage.setItem(
+			'origBlurStrength',
+			window.getComputedStyle(document.documentElement).getPropertyValue('--blur-strength')
+		);
+	}
+}
+
+// Check color validity
+const checkColorValidity = (colorStr) => {
+
+	// Check if RGBA - (#RRGGBBAA)
+	var colorRGBA = /^#[0-9A-F]{8}$/i.test(colorStr);
+
+	// If not RGBA
+	if (!colorRGBA) {
+
+		// If RGB - (#RRGGBB)
+		if (/^#([0-9A-F]{3}){1,2}$/i.test(colorStr)) {
+			
+			// Add completely opaque alpha
+			return colorStr + 'FF';
+		
+		// If three-charactered HEX color - (#RGB)
+		} else if (/^#([0-9A-F]{3}){1,2}$/i.test(colorStr)) {
+
+			// Convert it to RRGGBB
+			return colorStr.replace(/^#([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])/, "#$1$1$2$2$3$3");
+
+		// If three-charactered HEX Color(#RGB) with AA - (#RGBAA)
+		} else if (colorStr.length == 6) {
+
+			var bg = colorStr.slice(0, -2);
+			var op = colorStr.slice(-2);
+
+			return bg.replace(/^#([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])/, "#$1$1$2$2$3$3") + op;
+
+		} else {
+			alert('Invalid color');
+		}
+	}
+
+	// It's RGBA and a valid color so just return it
+	return colorStr;
+}
+
+// Update textboxes
+const updateTextBoxValues = (bgColor, bgOpacity, fgColor, fgOpacity, blurPower) => {
+	// Set placeholders
+	backgroundTextBox.value = '';
+	backgroundTextBox.placeholder = bgColor;
+
+	backgroundOpacityTextBox.value = '';
+	backgroundOpacityTextBox.placeholder = bgOpacity;
+
+	foregroundTextBox.value = '';
+	foregroundTextBox.placeholder = fgColor;
+	foregroundOpacityTextBox.value = '';
+	foregroundOpacityTextBox.placeholder = fgOpacity;
+
+	blurTextBox.value = '';
+	blurTextBox.placeholder = blurPower;
+}
+
+// Theme processing
+const processTheme = () => {
+
+	// Retrieve custom colors
+	var baseBG = localStorage.getItem('baseBG');
+	var baseColor = localStorage.getItem('baseColor');
+	var blurStrength = localStorage.getItem('blurStrength');
+
+	// If custom color doesn't exist, use the value in CSS
+	if (baseBG === null) {
+		baseBG = localStorage.getItem('origBaseBG');
+	}
+
+	if (baseColor === null) {
+		baseColor = localStorage.getItem('origBaseColor');
+	}
+
+	if (blurStrength === null) {
+		blurStrength = localStorage.getItem('origBlurStrength');
+	}
+
+	// Remove whitespace
+	baseBG = baseBG.replace(/ /g,'');
+	baseColor = baseColor.replace(/ /g,'');
+	blurStrength = blurStrength.replace(/ /g,'');
+
+	// Check validity
+	baseBG = checkColorValidity(baseBG);
+	baseColor = checkColorValidity(baseColor);
+
+	// Slice to separate RGB and A of background color
+	// Slice alpha out
+	var backgroundColor = baseBG.slice(0, -2);
+	// Get alpha
+	var backgroundOpacity = baseBG.slice(-2);
+
+
+	// Slice to separate RGB and A of foreground color		
+	// Slice alpha out
+	var foregroundColor = baseColor.slice(0, -2);
+	// Get alpha
+	var foregroundOpacity = baseColor.slice(-2);
+
+	updateTextBoxValues(
+		backgroundColor,
+		backgroundOpacity,
+		foregroundColor,
+		foregroundOpacity,
+		blurStrength
+	)
+}
+
+// Update colors
+const updateCSSVariables = () => {
+
+	// Get value from input fields
+	var background = (backgroundTextBox.value || backgroundTextBox.placeholder) +
+		(backgroundOpacityTextBox.value || backgroundOpacityTextBox.placeholder);
+
+	var foreground = (foregroundTextBox.value || foregroundTextBox.placeholder) +
+		(foregroundOpacityTextBox.value || foregroundOpacityTextBox.placeholder);
+	
+	var blurPower = (blurTextBox.value || blurTextBox.placeholder);
+
+	// Check color validity
+	var bgColor = checkColorValidity(background);
+	var fgColor = checkColorValidity(foreground);
+
+	// Change CSS colors
+	document.documentElement.style.setProperty('--base-bg', bgColor);
+	document.documentElement.style.setProperty('--base-color', fgColor);
+	document.documentElement.style.setProperty('--blur-strength', blurPower);
+
+	// Save custom color
+	localStorage.setItem('baseBG', bgColor);
+	localStorage.setItem('baseColor', fgColor);
+	localStorage.setItem('blurStrength', blurPower);
+
+	processTheme();
+}
+
+// Run on window onload
+const updateOnStartUp = () => {
+	// Update
+	processTheme();
+
+	// Update settings
+	updateCSSVariables();
+}
+
+// Apply button event handler
+applyTheme.onmouseup = () => {
+	updateCSSVariables();
+	alert('Success!');
+}
+
+// Reset button event handler
+resetTheme.onmouseup = () => {
+	localStorage.removeItem('baseBG');
+	localStorage.removeItem('baseColor');
+	localStorage.removeItem('blurStrength');
+
+	saveDefaultCSS();
+	processTheme();
+	updateCSSVariables();
+	
+	alert('Success!');
+}
+
+// Initialize
+const onStartUp = () => {
+	saveDefaultCSS();
+	updateOnStartUp();
+}
+
+// Call Initialize
+window.onload = onStartUp();
\ No newline at end of file