diff --git a/addons/xterm-addon-webgl/src/atlas/CharAtlasUtils.ts b/addons/xterm-addon-webgl/src/atlas/CharAtlasUtils.ts
index 1fd4c4f6b..03867b410 100644
--- a/addons/xterm-addon-webgl/src/atlas/CharAtlasUtils.ts
+++ b/addons/xterm-addon-webgl/src/atlas/CharAtlasUtils.ts
@@ -21,6 +21,7 @@ export function generateConfig(scaledCharWidth: number, scaledCharHeight: number
     cursor: NULL_COLOR,
     cursorAccent: NULL_COLOR,
     selection: NULL_COLOR,
+    selectionOpaque: NULL_COLOR,
     // For the static char atlas, we only use the first 16 colors, but we need all 256 for the
     // dynamic character atlas.
     ansi: colors.ansi.slice()
diff --git a/src/browser/Color.test.ts b/src/browser/Color.test.ts
new file mode 100644
index 000000000..fc75d4b90
--- /dev/null
+++ b/src/browser/Color.test.ts
@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2017 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { assert } from 'chai';
+import { blend } from 'browser/Color';
+
+describe('Color', () => {
+  describe('blend', () => {
+    it('should blend colors based on the alpha channel', () => {
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF00', rgba: 0xFFFFFF00 }), { css: '#000000', rgba: 0x000000FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF10', rgba: 0xFFFFFF10 }), { css: '#101010', rgba: 0x101010FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF20', rgba: 0xFFFFFF20 }), { css: '#202020', rgba: 0x202020FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF30', rgba: 0xFFFFFF30 }), { css: '#303030', rgba: 0x303030FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF40', rgba: 0xFFFFFF40 }), { css: '#404040', rgba: 0x404040FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF50', rgba: 0xFFFFFF50 }), { css: '#505050', rgba: 0x505050FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF60', rgba: 0xFFFFFF60 }), { css: '#606060', rgba: 0x606060FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF70', rgba: 0xFFFFFF70 }), { css: '#707070', rgba: 0x707070FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF80', rgba: 0xFFFFFF80 }), { css: '#808080', rgba: 0x808080FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFF90', rgba: 0xFFFFFF90 }), { css: '#909090', rgba: 0x909090FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFA0', rgba: 0xFFFFFFA0 }), { css: '#a0a0a0', rgba: 0xA0A0A0FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFB0', rgba: 0xFFFFFFB0 }), { css: '#b0b0b0', rgba: 0xB0B0B0FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFC0', rgba: 0xFFFFFFC0 }), { css: '#c0c0c0', rgba: 0xC0C0C0FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFD0', rgba: 0xFFFFFFD0 }), { css: '#d0d0d0', rgba: 0xD0D0D0FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFE0', rgba: 0xFFFFFFE0 }), { css: '#e0e0e0', rgba: 0xE0E0E0FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFF0', rgba: 0xFFFFFFF0 }), { css: '#f0f0f0', rgba: 0xF0F0F0FF });
+      assert.deepEqual(blend({ css: '#000000', rgba: 0x000000FF }, { css: '#FFFFFFFF', rgba: 0xFFFFFFFF }), { css: '#FFFFFFFF', rgba: 0xFFFFFFFF });
+    });
+  });
+});
diff --git a/src/browser/Color.ts b/src/browser/Color.ts
new file mode 100644
index 000000000..31087116b
--- /dev/null
+++ b/src/browser/Color.ts
@@ -0,0 +1,39 @@
+import { IColor } from './Types';
+
+export function blend(bg: IColor, fg: IColor): IColor {
+  const a = (fg.rgba & 0xFF) / 255;
+  if (a === 1) {
+    return {
+      css: fg.css,
+      rgba: fg.rgba
+    };
+  }
+  const fgR = (fg.rgba >> 24) & 0xFF;
+  const fgG = (fg.rgba >> 16) & 0xFF;
+  const fgB = (fg.rgba >> 8) & 0xFF;
+  const bgR = (bg.rgba >> 24) & 0xFF;
+  const bgG = (bg.rgba >> 16) & 0xFF;
+  const bgB = (bg.rgba >> 8) & 0xFF;
+  const r = bgR + Math.round((fgR - bgR) * a);
+  const g = bgG + Math.round((fgG - bgG) * a);
+  const b = bgB + Math.round((fgB - bgB) * a);
+  const css = toCss(r, g, b);
+  const rgba = ((r << 24) | (g << 16) | (b << 8) | 0xFF) >>> 0;
+  return { css, rgba };
+}
+
+export function fromCss(css: string): IColor {
+  return {
+    css,
+    rgba: parseInt(css.slice(1), 16) << 8 | 0xFF
+  };
+}
+
+export function toPaddedHex(c: number): string {
+  const s = c.toString(16);
+  return s.length < 2 ? '0' + s : s;
+}
+
+export function toCss(r: number, g: number, b: number): string {
+  return `#${toPaddedHex(r)}${toPaddedHex(g)}${toPaddedHex(b)}`;
+}
diff --git a/src/browser/ColorManager.ts b/src/browser/ColorManager.ts
index 70d21a7a4..a1bfc105e 100644
--- a/src/browser/ColorManager.ts
+++ b/src/browser/ColorManager.ts
@@ -5,11 +5,12 @@
 
 import { IColorManager, IColor, IColorSet } from 'browser/Types';
 import { ITheme } from 'common/services/Services';
+import { fromCss, toPaddedHex, toCss, blend } from 'browser/Color';
 
-const DEFAULT_FOREGROUND = fromHex('#ffffff');
-const DEFAULT_BACKGROUND = fromHex('#000000');
-const DEFAULT_CURSOR = fromHex('#ffffff');
-const DEFAULT_CURSOR_ACCENT = fromHex('#000000');
+const DEFAULT_FOREGROUND = fromCss('#ffffff');
+const DEFAULT_BACKGROUND = fromCss('#000000');
+const DEFAULT_CURSOR = fromCss('#ffffff');
+const DEFAULT_CURSOR_ACCENT = fromCss('#000000');
 const DEFAULT_SELECTION = {
   css: 'rgba(255, 255, 255, 0.3)',
   rgba: 0xFFFFFF77
@@ -20,23 +21,23 @@ const DEFAULT_SELECTION = {
 export const DEFAULT_ANSI_COLORS = (() => {
   const colors = [
     // dark:
-    fromHex('#2e3436'),
-    fromHex('#cc0000'),
-    fromHex('#4e9a06'),
-    fromHex('#c4a000'),
-    fromHex('#3465a4'),
-    fromHex('#75507b'),
-    fromHex('#06989a'),
-    fromHex('#d3d7cf'),
+    fromCss('#2e3436'),
+    fromCss('#cc0000'),
+    fromCss('#4e9a06'),
+    fromCss('#c4a000'),
+    fromCss('#3465a4'),
+    fromCss('#75507b'),
+    fromCss('#06989a'),
+    fromCss('#d3d7cf'),
     // bright:
-    fromHex('#555753'),
-    fromHex('#ef2929'),
-    fromHex('#8ae234'),
-    fromHex('#fce94f'),
-    fromHex('#729fcf'),
-    fromHex('#ad7fa8'),
-    fromHex('#34e2e2'),
-    fromHex('#eeeeec')
+    fromCss('#555753'),
+    fromCss('#ef2929'),
+    fromCss('#8ae234'),
+    fromCss('#fce94f'),
+    fromCss('#729fcf'),
+    fromCss('#ad7fa8'),
+    fromCss('#34e2e2'),
+    fromCss('#eeeeec')
   ];
 
   // Fill in the remaining 240 ANSI colors.
@@ -47,7 +48,7 @@ export const DEFAULT_ANSI_COLORS = (() => {
     const g = v[(i / 6) % 6 | 0];
     const b = v[i % 6];
     colors.push({
-      css: `#${toPaddedHex(r)}${toPaddedHex(g)}${toPaddedHex(b)}`,
+      css: toCss(r, g, b),
       // Use >>> 0 to force a conversion to an unsigned int
       rgba: ((r << 24) | (g << 16) | (b << 8) | 0xFF) >>> 0
     });
@@ -66,18 +67,6 @@ export const DEFAULT_ANSI_COLORS = (() => {
   return colors;
 })();
 
-function fromHex(css: string): IColor {
-  return {
-    css,
-    rgba: parseInt(css.slice(1), 16) << 8 | 0xFF
-  };
-}
-
-function toPaddedHex(c: number): string {
-  const s = c.toString(16);
-  return s.length < 2 ? '0' + s : s;
-}
-
 /**
  * Manages the source of truth for a terminal's colors.
  */
@@ -103,6 +92,7 @@ export class ColorManager implements IColorManager {
       cursor: DEFAULT_CURSOR,
       cursorAccent: DEFAULT_CURSOR_ACCENT,
       selection: DEFAULT_SELECTION,
+      selectionOpaque: blend(DEFAULT_BACKGROUND, DEFAULT_SELECTION),
       ansi: DEFAULT_ANSI_COLORS.slice()
     };
   }
diff --git a/src/browser/Types.d.ts b/src/browser/Types.d.ts
index aa7a4c86e..ca852b6aa 100644
--- a/src/browser/Types.d.ts
+++ b/src/browser/Types.d.ts
@@ -21,6 +21,8 @@ export interface IColorSet {
   cursor: IColor;
   cursorAccent: IColor;
   selection: IColor;
+  /** The selection blended on top of background. */
+  selectionOpaque: IColor;
   ansi: IColor[];
 }