diff --git a/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-style/set.js b/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-style/set.js
index 50b65947a854..65345a6708dc 100644
--- a/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-style/set.js
+++ b/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-style/set.js
@@ -23,8 +23,10 @@
 // MODULES //
 
 var logger = require( 'debug' );
-var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
 var isUndefined = require( '@stdlib/assert/is-undefined' );
+var isFontStyle = require( '@stdlib/plot/vega/base/assert/is-font-style' );
+var join = require( '@stdlib/array/base/join' );
+var fontStyles = require( '@stdlib/plot/vega/base/font-styles' );
 var format = require( '@stdlib/string/format' );
 var changeEvent = require( './../change_event.js' );
 var prop = require( './properties.js' );
@@ -46,12 +48,12 @@ var debug = logger( 'vega:title:set:'+prop.name );
 *
 * @private
 * @param {(string|void)} value - input value
-* @throws {TypeError} must be a string
+* @throws {TypeError} must be a valid font style
 * @returns {void}
 */
 function set( value ) {
-	if ( !isString( value ) && !isUndefined( value ) ) {
-		throw new TypeError( format( 'invalid assignment. `%s` must be a string. Value: `%s`.', prop.name, value ) );
+	if ( !isUndefined( value ) && !isFontStyle( value ) ) {
+		throw new TypeError( format( 'invalid assignment. `%s` must be one of the following: "%s". Value: `%s`.', prop.name, join( fontStyles(), '", "' ), value ) );
 	}
 	if ( value !== this[ prop.private ] ) {
 		debug( 'Current value: %s. New value: %s.', this[ prop.private ], value );
diff --git a/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-weight/set.js b/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-weight/set.js
index 2d105394e6d8..ac841716d904 100644
--- a/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-weight/set.js
+++ b/lib/node_modules/@stdlib/plot/vega/title/ctor/lib/font-weight/set.js
@@ -23,9 +23,11 @@
 // MODULES //
 
 var logger = require( 'debug' );
-var isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
-var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
 var isUndefined = require( '@stdlib/assert/is-undefined' );
+var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
+var isFontWeight = require( '@stdlib/plot/vega/base/assert/is-font-weight' );
+var join = require( '@stdlib/array/base/join' );
+var fontWeights = require( '@stdlib/plot/vega/base/font-weights' );
 var format = require( '@stdlib/string/format' );
 var changeEvent = require( './../change_event.js' );
 var prop = require( './properties.js' );
@@ -47,12 +49,15 @@ var debug = logger( 'vega:title:set:'+prop.name );
 *
 * @private
 * @param {(number|string|void)} value - input value
-* @throws {TypeError} must be a number or string
+* @throws {TypeError} must be a valid font weight
 * @returns {void}
 */
 function set( value ) {
-	if ( !isNumber( value ) && !isString( value ) && !isUndefined( value ) ) {
-		throw new TypeError( format( 'invalid assignment. `%s` must be a number or string. Value: `%s`.', prop.name, value ) );
+	if ( isNonNegativeInteger( value ) ) {
+		value = String( value );
+	}
+	if ( !isUndefined( value ) && !isFontWeight( value ) ) {
+		throw new TypeError( format( 'invalid assignment. `%s` must be one of the following: "%s". Value: `%s`.', prop.name, join( fontWeights(), '", "' ), value ) );
 	}
 	if ( value !== this[ prop.private ] ) {
 		debug( 'Current value: %s. New value: %s.', this[ prop.private ], value );
diff --git a/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_style.js b/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_style.js
index 937e9cb8bac9..f4c1d50fb9bc 100644
--- a/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_style.js
+++ b/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_style.js
@@ -43,7 +43,7 @@ tape( 'the constructor returns an instance which has a `fontStyle` property', fu
 	t.strictEqual( isUndefined( v.fontStyle ), true, 'returns expected value' );
 
 	v = new Title({
-		'fontStyle': 'Arial'
+		'fontStyle': 'italic'
 	});
 	t.strictEqual( isString( v.fontStyle ), true, 'returns expected value' );
 
@@ -55,6 +55,8 @@ tape( 'the constructor returns an instance having a `fontStyle` property which t
 	var i;
 
 	values = [
+		'Arial',
+		'foo',
 		5,
 		NaN,
 		null,
@@ -82,14 +84,14 @@ tape( 'the constructor returns an instance having a `fontStyle` property', funct
 	t.strictEqual( isUndefined( title.fontStyle ), true, 'returns expected value' );
 
 	title = new Title({
-		'fontStyle': 'Arial'
+		'fontStyle': 'italic'
 	});
-	t.strictEqual( title.fontStyle, 'Arial', 'returns expected value' );
+	t.strictEqual( title.fontStyle, 'italic', 'returns expected value' );
 
 	title = new Title({
-		'fontStyle': 'Sans'
+		'fontStyle': 'oblique'
 	});
-	t.strictEqual( title.fontStyle, 'Sans', 'returns expected value' );
+	t.strictEqual( title.fontStyle, 'oblique', 'returns expected value' );
 
 	t.end();
 });
@@ -97,11 +99,11 @@ tape( 'the constructor returns an instance having a `fontStyle` property', funct
 tape( 'the constructor returns an instance having a `fontStyle` property which can be set to a valid value', function test( t ) {
 	var title = new Title();
 
-	title.fontStyle = 'Arial';
-	t.strictEqual( title.fontStyle, 'Arial', 'returns expected value' );
+	title.fontStyle = 'italic';
+	t.strictEqual( title.fontStyle, 'italic', 'returns expected value' );
 
-	title.fontStyle = 'Sans';
-	t.strictEqual( title.fontStyle, 'Sans', 'returns expected value' );
+	title.fontStyle = 'oblique';
+	t.strictEqual( title.fontStyle, 'oblique', 'returns expected value' );
 
 	t.end();
 });
@@ -115,14 +117,14 @@ tape( 'the constructor returns an instance which emits an event when the `fontSt
 
 	title.on( 'change', onChange );
 
-	title.fontStyle = 'Sans';
+	title.fontStyle = 'italic';
 	t.strictEqual( count, 1, 'returns expected value' );
 
-	title.fontStyle = 'Arial';
+	title.fontStyle = 'oblique';
 	t.strictEqual( count, 2, 'returns expected value' );
 
 	// Setting to the same value should not emit an event:
-	title.fontStyle = 'Arial';
+	title.fontStyle = 'oblique';
 	t.strictEqual( count, 2, 'returns expected value' );
 
 	t.end();
diff --git a/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_weight.js b/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_weight.js
index 9ef9cd6a4339..763531d226c5 100644
--- a/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_weight.js
+++ b/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.font_weight.js
@@ -25,7 +25,6 @@ var hasOwnProp = require( '@stdlib/assert/has-own-property' );
 var isUndefined = require( '@stdlib/assert/is-undefined' );
 var hasProp = require( '@stdlib/assert/has-property' );
 var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
-var isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
 var Title = require( './../lib' );
 
 
@@ -49,9 +48,9 @@ tape( 'the constructor returns an instance which has a `fontWeight` property', f
 	t.strictEqual( isString( v.fontWeight ), true, 'returns expected value' );
 
 	v = new Title({
-		'fontWeight': 6
+		'fontWeight': 600
 	});
-	t.strictEqual( isNumber( v.fontWeight ), true, 'returns expected value' );
+	t.strictEqual( isString( v.fontWeight ), true, 'returns expected value' );
 
 	t.end();
 });
@@ -61,6 +60,9 @@ tape( 'the constructor returns an instance having a `fontWeight` property which
 	var i;
 
 	values = [
+		'foo',
+		6,
+		NaN,
 		null,
 		true,
 		false,
@@ -91,19 +93,19 @@ tape( 'the constructor returns an instance having a `fontWeight` property', func
 	t.strictEqual( title.fontWeight, 'bold', 'returns expected value' );
 
 	title = new Title({
-		'fontWeight': 'light'
+		'fontWeight': 'lighter'
 	});
-	t.strictEqual( title.fontWeight, 'light', 'returns expected value' );
+	t.strictEqual( title.fontWeight, 'lighter', 'returns expected value' );
 
 	title = new Title({
-		'fontWeight': 6
+		'fontWeight': '600'
 	});
-	t.strictEqual( title.fontWeight, 6, 'returns expected value' );
+	t.strictEqual( title.fontWeight, '600', 'returns expected value' );
 
 	title = new Title({
-		'fontWeight': 8
+		'fontWeight': 800
 	});
-	t.strictEqual( title.fontWeight, 8, 'returns expected value' );
+	t.strictEqual( title.fontWeight, '800', 'returns expected value' );
 
 	t.end();
 });
@@ -114,14 +116,14 @@ tape( 'the constructor returns an instance having a `fontWeight` property which
 	title.fontWeight = 'bold';
 	t.strictEqual( title.fontWeight, 'bold', 'returns expected value' );
 
-	title.fontWeight = 'light';
-	t.strictEqual( title.fontWeight, 'light', 'returns expected value' );
+	title.fontWeight = 'lighter';
+	t.strictEqual( title.fontWeight, 'lighter', 'returns expected value' );
 
-	title.fontWeight = 6;
-	t.strictEqual( title.fontWeight, 6, 'returns expected value' );
+	title.fontWeight = '600';
+	t.strictEqual( title.fontWeight, '600', 'returns expected value' );
 
-	title.fontWeight = 8;
-	t.strictEqual( title.fontWeight, 8, 'returns expected value' );
+	title.fontWeight = 800;
+	t.strictEqual( title.fontWeight, '800', 'returns expected value' );
 
 	t.end();
 });
@@ -135,7 +137,7 @@ tape( 'the constructor returns an instance which emits an event when the `fontWe
 
 	title.on( 'change', onChange );
 
-	title.fontWeight = 'light';
+	title.fontWeight = 'lighter';
 	t.strictEqual( count, 1, 'returns expected value' );
 
 	title.fontWeight = 'bold';
diff --git a/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.js b/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.js
index eeaba0114550..11cfcad05fde 100644
--- a/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.js
+++ b/lib/node_modules/@stdlib/plot/vega/title/ctor/test/test.js
@@ -380,6 +380,8 @@ tape( 'the constructor throws an error if provided an invalid `fontStyle` option
 	var i;
 
 	values = [
+		'Arial',
+		'foo',
 		5,
 		NaN,
 		null,
@@ -408,6 +410,9 @@ tape( 'the constructor throws an error if provided an invalid `fontWeight` optio
 	var i;
 
 	values = [
+		'foo',
+		6,
+		NaN,
 		null,
 		true,
 		false,
@@ -903,7 +908,7 @@ tape( 'the constructor returns an instance having a `toJSON` method for serializ
 		},
 		'font': 'Arial',
 		'fontSize': 12,
-		'fontStyle': 'Arial',
+		'fontStyle': 'italic',
 		'fontWeight': 'bold',
 		'frame': 'group',
 		'limit': 100,
@@ -942,7 +947,7 @@ tape( 'the constructor returns an instance having a `toJSON` method for serializ
 		},
 		'font': 'Arial',
 		'fontSize': 12,
-		'fontStyle': 'Arial',
+		'fontStyle': 'italic',
 		'fontWeight': 'bold',
 		'frame': 'group',
 		'limit': 100,