diff --git a/xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/xwiki-platform-flamingo-skin-resources/src/main/resources/flamingo/less/messages.less b/xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/xwiki-platform-flamingo-skin-resources/src/main/resources/flamingo/less/messages.less
index 72725e49e180..b32151f90d26 100644
--- a/xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/xwiki-platform-flamingo-skin-resources/src/main/resources/flamingo/less/messages.less
+++ b/xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/xwiki-platform-flamingo-skin-resources/src/main/resources/flamingo/less/messages.less
@@ -2,10 +2,49 @@
 // Messages
 // --------------------------------------------------
 
-.successmessage, .errormessage, .warningmessage, .infomessage,
-span.successmessage, span.errormessage, span.warningmessage, span.infomessage, 
-span.box { // Used by: Inline boxes and messages
-  padding: floor(@font-size-base * 0.2);
+// Used by: Inline boxes
+span.successmessage, span.errormessage, span.warningmessage, span.infomessage {
+  padding: 0 floor(@font-size-base * 0.2);
+  border: none;
+  box-shadow: none;
+  & > img {
+    // Style the silk icons
+    margin: 0 .6rem 0 .2rem;
+    vertical-align: sub;
+  }
+
+  & > span.fa {
+    // Style the font awesome icons
+    margin: 0 .6rem 0 .2rem;
+  }
+}
+
+// Used by: message boxes
+div.successmessage, div.errormessage, div.warningmessage, div.infomessage {
+  display: flex;
+  gap: 2rem;
+  justify-content: left;
+  align-items: baseline;
+  padding: 2rem;
+  border: none;
+  border-left: 4px solid;
+  box-shadow: none;
+
+  & > img {
+    // Improve alignment for silk icons
+    align-self: flex-start;
+  }
+
+  & > div > .box-title,
+  & > div > .xwiki-metadata-container[data-xwiki-parameter-name="title"] {
+    font-weight: bold;
+  }
+
+  // Main message content
+  & > div > p,
+  & > div > [data-cke-display-name="$content"] {
+    margin: 0;
+  }
 }
 
 .box, .plainmessage, // Used by: Code Macro, Success Macro, etc.
@@ -28,21 +67,25 @@ fieldset.xwikimessage { // Used by: Login form, Delete messages
 .successmessage {
   .alert-success;
   background-color: @state-success-bg;
+  border-color: @brand-success;
 }
 
 .errormessage {
   .alert-danger;
   background-color: @state-danger-bg;
+  border-color: @brand-danger;
 }
 
 .warningmessage {
   .alert-warning;
   background-color: @state-warning-bg;
+  border-color: @brand-warning;
 }
 
 .infomessage {
   .alert-info;
   background-color: @state-info-bg;
+  border-color: @brand-primary;
 }
 
 // --------------------------------------------------
diff --git a/xwiki-platform-core/xwiki-platform-icon/xwiki-platform-icon-fontawesome/src/main/resources/IconThemes/FontAwesome.xml b/xwiki-platform-core/xwiki-platform-icon/xwiki-platform-icon-fontawesome/src/main/resources/IconThemes/FontAwesome.xml
index f12f51c8a704..184c414827dc 100644
--- a/xwiki-platform-core/xwiki-platform-icon/xwiki-platform-icon-fontawesome/src/main/resources/IconThemes/FontAwesome.xml
+++ b/xwiki-platform-core/xwiki-platform-icon/xwiki-platform-icon-fontawesome/src/main/resources/IconThemes/FontAwesome.xml
@@ -288,7 +288,8 @@ disk = floppy-o
 drink = glass
 drive = hdd-o
 email = envelope-o
-emoticon_smile=smile-o
+emoticon_smile= smile-o
+emoticon_unhappy = frown-o
 error = exclamation-triangle
 exclamation = exclamation-circle
 eye = eye
diff --git a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/pom.xml b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/pom.xml
index 628faf61249c..6eca438898a3 100644
--- a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/pom.xml
+++ b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/pom.xml
@@ -108,6 +108,16 @@
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpclient</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.xwiki.platform</groupId>
+      <artifactId>xwiki-platform-icon-api</artifactId>
+      <version>${project.version}</version>
+    </dependency>
+    <dependency>
+      <groupId>org.xwiki.platform</groupId>
+      <artifactId>xwiki-platform-localization-api</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <!--dependency>
       <groupId>javax.servlet</groupId>
       <artifactId>javax.servlet-api</artifactId>
diff --git a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/java/org/xwiki/rendering/internal/util/XWikiIconProvider.java b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/java/org/xwiki/rendering/internal/util/XWikiIconProvider.java
new file mode 100644
index 000000000000..89abd57a1e0b
--- /dev/null
+++ b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/java/org/xwiki/rendering/internal/util/XWikiIconProvider.java
@@ -0,0 +1,96 @@
+/*
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.xwiki.rendering.internal.util;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+import org.xwiki.component.annotation.Component;
+import org.xwiki.icon.IconException;
+import org.xwiki.icon.IconRenderer;
+import org.xwiki.icon.IconSet;
+import org.xwiki.icon.IconSetManager;
+import org.xwiki.localization.ContextualLocalizationManager;
+import org.xwiki.rendering.block.Block;
+import org.xwiki.rendering.block.CompositeBlock;
+import org.xwiki.rendering.block.FormatBlock;
+import org.xwiki.rendering.block.RawBlock;
+import org.xwiki.rendering.block.WordBlock;
+import org.xwiki.rendering.listener.Format;
+import org.xwiki.rendering.syntax.Syntax;
+
+import java.util.List;
+
+/**
+ * Component to use the icon theme to provide a proper block for displaying an icon.
+ *
+ * @version $Id$
+ * @since 15.10.6
+ * @since 16.1.0RC1
+ */
+@Component
+@Singleton
+public class XWikiIconProvider extends DefaultIconProvider
+{
+    @Inject
+    private IconSetManager iconSetManager;
+    @Inject
+    private IconRenderer iconRenderer;
+    @Inject
+    private ContextualLocalizationManager l10n;
+
+    /**
+     * Uses the icon theme to provide the right block for displaying an icon.
+     * @param iconName the name of the icon to display
+     * @return the block containing an icon.
+     */
+    @Override
+    public Block get(String iconName)
+    {
+        IconSet iconSet = null;
+        try {
+            iconSet = getIconSet(iconName);
+            String iconContent = this.iconRenderer.renderHTML(iconName, iconSet);
+            Block iconAlternative;
+            try {
+                // Try to retrieve a translation for the icon.
+                iconAlternative = new FormatBlock(List.of(l10n.getTranslation(
+                    String.format("rendering.icon.provider.icon.alternative.%s", iconName)).render()), Format.NONE);
+            } catch (Exception e) {
+                // As a fallback, we just get the english name of the icon as an alternative.
+                iconAlternative = new FormatBlock(List.of(new WordBlock(iconName)), Format.NONE);
+            }
+            iconAlternative.setParameter("class", "sr-only");
+            Block iconRaw = new RawBlock(iconContent, Syntax.HTML_5_0);
+            // We return a combination of the icon itself and its text alternative.
+            return new CompositeBlock(List.of(iconRaw, iconAlternative));
+        } catch (IconException e) {
+            return super.get(iconName);
+        }
+    }
+
+    private IconSet getIconSet(String iconName) throws IconException
+    {
+        IconSet iconSet = this.iconSetManager.getCurrentIconSet();
+        if (iconSet == null || !iconSet.hasIcon(iconName)) {
+            iconSet = this.iconSetManager.getDefaultIconSet();
+        }
+        return iconSet;
+    }
+}
diff --git a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/ApplicationResources.properties b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/ApplicationResources.properties
index a9311eca90b0..104501738873 100644
--- a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/ApplicationResources.properties
+++ b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/ApplicationResources.properties
@@ -42,6 +42,12 @@
 #     old.key.name=Some translation
 ###############################################################################
 
+# Those entries are used to label the message boxes of different types.
+rendering.icon.provider.icon.alternative.information=Information
+rendering.icon.provider.icon.alternative.accept=Success
+rendering.icon.provider.icon.alternative.error=Warning
+rendering.icon.provider.icon.alternative.exclamation=Error
+
 rendering.error.causedBy=Cause: [{0}].
 rendering.error.click=Click on this message for details.
 rendering.macro.rawMacroRequiredRights=Using the raw macro for HTML content requires script right.
diff --git a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/META-INF/components.txt b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/META-INF/components.txt
index 235f63519a7b..a1627d0569eb 100644
--- a/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/META-INF/components.txt
+++ b/xwiki-platform-core/xwiki-platform-rendering/xwiki-platform-rendering-xwiki/src/main/resources/META-INF/components.txt
@@ -1,6 +1,7 @@
 500:org.xwiki.rendering.internal.renderer.XWikiAttachmentURILabelGenerator
 500:org.xwiki.rendering.internal.renderer.XWikiLinkLabelGenerator
 500:org.xwiki.rendering.internal.renderer.XWikiPageAttachmentURILabelGenerator
+500:org.xwiki.rendering.internal.util.XWikiIconProvider
 500:org.xwiki.rendering.internal.util.XWikiErrorBlockGenerator
 500:org.xwiki.rendering.internal.wiki.XWikiWikiModel
 500:org.xwiki.rendering.internal.macro.XWikiHTMLRawBlockFilter