diff --git a/core/lib/Drupal/Core/Layout/Icon/SvgIconBuilder.php b/core/lib/Drupal/Core/Layout/Icon/SvgIconBuilder.php
index 29adc583dc..e7218b3c29 100644
--- a/core/lib/Drupal/Core/Layout/Icon/SvgIconBuilder.php
+++ b/core/lib/Drupal/Core/Layout/Icon/SvgIconBuilder.php
@@ -28,14 +28,14 @@ class SvgIconBuilder implements IconBuilderInterface {
    *
    * @var int
    */
-  protected $width = 250;
+  protected $width = 125;
 
   /**
    * The height of the SVG.
    *
    * @var int
    */
-  protected $height = 300;
+  protected $height = 150;
 
   /**
    * The padding between regions.
@@ -49,7 +49,7 @@ class SvgIconBuilder implements IconBuilderInterface {
    *
    * @var int|null
    */
-  protected $strokeWidth = 2;
+  protected $strokeWidth = 1;
 
   /**
    * {@inheritdoc}
diff --git a/core/lib/Drupal/Core/Layout/LayoutDefinition.php b/core/lib/Drupal/Core/Layout/LayoutDefinition.php
index 967a0a38e9..c87b618d11 100644
--- a/core/lib/Drupal/Core/Layout/LayoutDefinition.php
+++ b/core/lib/Drupal/Core/Layout/LayoutDefinition.php
@@ -414,15 +414,14 @@ public function setIconMap($icon_map) {
    *   (optional) The height of the icon. Defaults to 150.
    * @param int $stroke_width
    *   (optional) If an icon map is used, the width of region borders.
-   *   Defaults to 1.
    * @param int $padding
    *   (optional) If an icon map is used, the padding between regions. Any
-   *   value above 0 is valid. Defaults to 4.
+   *   value above 0 is valid.
    *
    * @return array
    *   A render array for the icon.
    */
-  public function getIcon($width = 125, $height = 150, $stroke_width = 1, $padding = 4) {
+  public function getIcon($width = 125, $height = 150, $stroke_width = NULL, $padding = NULL) {
     $icon = [];
     if ($icon_path = $this->getIconPath()) {
       $icon = [
@@ -438,9 +437,13 @@ public function getIcon($width = 125, $height = 150, $stroke_width = 1, $padding
         ->setId($this->id())
         ->setLabel($this->getLabel())
         ->setWidth($width)
-        ->setHeight($height)
-        ->setPadding($padding)
-        ->setStrokeWidth($stroke_width);
+        ->setHeight($height);
+      if ($padding) {
+        $icon_builder->setPadding($padding);
+      }
+      if ($stroke_width) {
+        $icon_builder->setStrokeWidth($stroke_width);
+      }
       $icon = $icon_builder->build($icon_map);
     }
     return $icon;
diff --git a/core/misc/dialog/off-canvas.layout.css b/core/misc/dialog/off-canvas.layout.css
index 3b2b52e387..aa3a5373ea 100644
--- a/core/misc/dialog/off-canvas.layout.css
+++ b/core/misc/dialog/off-canvas.layout.css
@@ -1,6 +1,8 @@
 /**
  * @file
  * Visual styling for layouts in the off-canvas dialog.
+ *
+ * See seven/css/layout/layout.css
  */
 
 .layout-icon__region {
diff --git a/core/tests/Drupal/KernelTests/Core/Layout/IconBuilderTest.php b/core/tests/Drupal/KernelTests/Core/Layout/IconBuilderTest.php
index ac9d380808..13738e401c 100644
--- a/core/tests/Drupal/KernelTests/Core/Layout/IconBuilderTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Layout/IconBuilderTest.php
@@ -24,6 +24,7 @@ class IconBuilderTest extends KernelTestBase {
   public function testBuild(SvgIconBuilder $icon_builder, $icon_map, $expected) {
     $renderer = $this->container->get('renderer');
 
+    $icon_builder->setWidth(250)->setHeight(300);
     $build = $icon_builder->build($icon_map);
 
     $output = (string) $renderer->executeInRenderContext(new RenderContext(), function () use ($build, $renderer) {
@@ -43,7 +44,8 @@ public function providerTestBuild() {
 
     $data['two_column'][] = (new SvgIconBuilder())
       ->setId('two_column')
-      ->setLabel('Two Column');
+      ->setLabel('Two Column')
+      ->setStrokeWidth(2);
     $data['two_column'][] = [['left', 'right']];
     $data['two_column'][] = <<<'EOD'
 <svg width="250" height="300" class="layout-icon layout-icon--two-column"><title>Two Column</title>
@@ -72,6 +74,7 @@ public function providerTestBuild() {
 EOD;
 
     $data['two_column_border_collapse'][] = (new SvgIconBuilder())
+      ->setStrokeWidth(2)
       ->setPadding(-2);
     $data['two_column_border_collapse'][] = [['left', 'right']];
     $data['two_column_border_collapse'][] = <<<'EOD'
@@ -85,7 +88,8 @@ public function providerTestBuild() {
 
 EOD;
 
-    $data['stacked'][] = (new SvgIconBuilder());
+    $data['stacked'][] = (new SvgIconBuilder())
+      ->setStrokeWidth(2);
     $data['stacked'][] = [
       ['sidebar', 'top', 'top'],
       ['sidebar', 'left', 'right'],
diff --git a/core/themes/seven/css/layout/layout.css b/core/themes/seven/css/layout/layout.css
index eb7c2bf0b3..39649e43c1 100644
--- a/core/themes/seven/css/layout/layout.css
+++ b/core/themes/seven/css/layout/layout.css
@@ -4,3 +4,11 @@
 .page-content {
   margin-bottom: 80px;
 }
+
+/**
+ * Add color to layout icons.
+ */
+.layout-icon__region {
+  fill: #f5f5f2;
+  stroke: #666;
+}
diff --git a/core/themes/stable/css/core/dialog/off-canvas.layout.css b/core/themes/stable/css/core/dialog/off-canvas.layout.css
index 3b2b52e387..aa3a5373ea 100644
--- a/core/themes/stable/css/core/dialog/off-canvas.layout.css
+++ b/core/themes/stable/css/core/dialog/off-canvas.layout.css
@@ -1,6 +1,8 @@
 /**
  * @file
  * Visual styling for layouts in the off-canvas dialog.
+ *
+ * See seven/css/layout/layout.css
  */
 
 .layout-icon__region {