Restructure solution a bit

src/Spectre.Console/Style.cs

@@ -7,7 +7,7 @@ namespace Spectre.Console
     /// <summary>
     /// Represents color and text decoration.
     /// </summary>
-    public sealed partial class Style : IEquatable<Style>
+    public sealed class Style : IEquatable<Style>
     {
         /// <summary>
         /// Gets the foreground color.
@@ -48,6 +48,36 @@ namespace Spectre.Console
             Decoration = decoration ?? Decoration.None;
         }
 
+        /// <summary>
+        /// Creates a new style from the specified foreground color.
+        /// </summary>
+        /// <param name="color">The foreground color.</param>
+        /// <returns>A new <see cref="Style"/> with the specified foreground color.</returns>
+        public static Style WithForeground(Color color)
+        {
+            return new Style(foreground: color);
+        }
+
+        /// <summary>
+        /// Creates a new style from the specified background color.
+        /// </summary>
+        /// <param name="color">The background color.</param>
+        /// <returns>A new <see cref="Style"/> with the specified background color.</returns>
+        public static Style WithBackground(Color color)
+        {
+            return new Style(background: color);
+        }
+
+        /// <summary>
+        /// Creates a new style from the specified text decoration.
+        /// </summary>
+        /// <param name="decoration">The text decoration.</param>
+        /// <returns>A new <see cref="Style"/> with the specified text decoration.</returns>
+        public static Style WithDecoration(Decoration decoration)
+        {
+            return new Style(decoration: decoration);
+        }
+
         /// <summary>
         /// Creates a copy of the current <see cref="Style"/>.
         /// </summary>