diff --git a/Sources/Slipstream/TailwindCSS/Color.swift b/Sources/Slipstream/TailwindCSS/Color.swift
index 5483180..d1e8f2c 100644
--- a/Sources/Slipstream/TailwindCSS/Color.swift
+++ b/Sources/Slipstream/TailwindCSS/Color.swift
@@ -13,10 +13,19 @@ public struct Color {
   /// Creates a Color instance using a Tailwind CSS palette instance.
   public init(_ colorPalette: ColorPalette, darkness: Int) {
     self.storage = .palette(colorPalette, darkness: darkness)
+    self.opacity = 1
+  }
+
+  /// Multiplies the opacity of the color by the given amount.
+  public func opacity(_ opacity: Double) -> Self {
+    var copy = self
+    copy.opacity *= opacity
+    return copy
   }
 
   init(_ value: Storage) {
     self.storage = value
+    self.opacity = 1
   }
 
   enum Storage {
@@ -25,9 +34,18 @@ public struct Color {
     case palette(ColorPalette, darkness: Int)
   }
   private let storage: Storage
+  private var opacity: Double
 
   /// Returns the Tailwind CSS color class for this color.
   func toTailwindColorClass() -> String {
+    if opacity < 1 {
+      return colorClass + "/" + opacityClass
+    }
+    return colorClass
+  }
+
+  /// Returns the Tailwind CSS color class for this color.
+  private var colorClass: String {
     switch storage {
     case .black:
       return "black"
@@ -37,4 +55,36 @@ public struct Color {
       return colorPalette.closestTailwindColorStop(for: darkness)
     }
   }
+
+  /// Maps the opacity to the closest Tailwind CSS opacity class.
+  ///
+  /// - Parameter size: The size in points to be mapped.
+  /// - Returns: The Tailwind CSS placement class.
+  var opacityClass: String {
+    let mapping: [(name: String, opacity: Double)] = [
+      ("0", 0.0),
+      ("5", 0.05),
+      ("10", 0.10),
+      ("15", 0.15),
+      ("20", 0.20),
+      ("25", 0.25),
+      ("30", 0.30),
+      ("35", 0.35),
+      ("40", 0.40),
+      ("45", 0.45),
+      ("50", 0.50),
+      ("55", 0.55),
+      ("60", 0.60),
+      ("65", 0.65),
+      ("70", 0.70),
+      ("75", 0.75),
+      ("80", 0.80),
+      ("85", 0.85),
+      ("90", 0.90),
+      ("95", 0.95),
+      ("100", 0.100),
+    ]
+    let closestClass = mapping.min { abs($0.opacity - opacity) < abs($1.opacity - opacity) }
+    return closestClass?.name ?? "0"
+  }
 }
diff --git a/Tests/SlipstreamTests/TailwindCSS/Backgrounds/BackgroundColorTests.swift b/Tests/SlipstreamTests/TailwindCSS/Backgrounds/BackgroundColorTests.swift
index 24d5bf3..cd9b6e4 100644
--- a/Tests/SlipstreamTests/TailwindCSS/Backgrounds/BackgroundColorTests.swift
+++ b/Tests/SlipstreamTests/TailwindCSS/Backgrounds/BackgroundColorTests.swift
@@ -13,4 +13,10 @@ struct BackgroundColorTests {
   @Test func colorWithDarkness() throws {
     try #expect(renderHTML(Div {}.background(.cyan, darkness: 500)) == #"<div class="bg-cyan-500"></div>"#)
   }
+
+  @Test func colorWithOpacity() throws {
+    try #expect(renderHTML(Div {}.background(.init(.cyan, darkness: 500).opacity(0))) == #"<div class="bg-cyan-500/0"></div>"#)
+    try #expect(renderHTML(Div {}.background(.init(.cyan, darkness: 500).opacity(0.5))) == #"<div class="bg-cyan-500/50"></div>"#)
+    try #expect(renderHTML(Div {}.background(.init(.cyan, darkness: 500).opacity(20))) == #"<div class="bg-cyan-500"></div>"#)
+  }
 }