diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5eaee41
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/.gradle
+/.idea
+build
\ No newline at end of file
diff --git a/beasts/frog.jpg b/beasts/frog.jpg
new file mode 100644
index 0000000..6ebf852
Binary files /dev/null and b/beasts/frog.jpg differ
diff --git a/beasts/snake.jpg b/beasts/snake.jpg
new file mode 100644
index 0000000..be459b7
Binary files /dev/null and b/beasts/snake.jpg differ
diff --git a/beasts/turtle.jpg b/beasts/turtle.jpg
new file mode 100644
index 0000000..9d62d39
Binary files /dev/null and b/beasts/turtle.jpg differ
diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000..c16be97
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,30 @@
+buildscript {
+    ext.kotlin_version = '1.1.60'
+
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+version '1.0-SNAPSHOT'
+
+allprojects {
+    apply plugin: 'kotlin2js'
+    apply plugin: 'kotlin-dce-js'
+
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        compile "org.jetbrains.kotlin:kotlin-stdlib-js:$kotlin_version"
+    }
+
+    compileKotlin2Js {
+        kotlinOptions.sourceMap = true
+        kotlinOptions.sourceMapEmbedSources = "always"
+    }
+}
\ No newline at end of file
diff --git a/content_script/src/main/kotlin/content_script.kt b/content_script/src/main/kotlin/content_script.kt
new file mode 100644
index 0000000..cab4792
--- /dev/null
+++ b/content_script/src/main/kotlin/content_script.kt
@@ -0,0 +1,41 @@
+import org.w3c.dom.HTMLElement
+import org.w3c.dom.asList
+import org.w3c.dom.get
+import kotlin.browser.document
+import kotlin.browser.window
+
+fun main(args: Array<String>) {
+    if (window["hasRun"] == true) {
+        return
+    }
+    window.asDynamic()["hasRun"] = true
+
+    browser.runtime.onMessage.addListener { message ->
+        if (message.command === "beastify") {
+            insertBeast(message.beastURL)
+        } else if (message.command === "reset") {
+            removeExistingBeasts()
+        }
+    }
+}
+
+fun insertBeast(beastURL: String) {
+    removeExistingBeasts()
+
+    val beastImage = document.createElement("img") as HTMLElement
+    beastImage.run {
+        setAttribute("src", beastURL)
+        style.height = "100vh"
+        className = "beastify-image"
+    }
+
+    document.body?.appendChild(beastImage)
+}
+
+fun removeExistingBeasts() {
+    val existingBeasts = document.querySelectorAll(".beastify-image")
+
+    for (beast in existingBeasts.asList()) {
+        beast.parentNode?.removeChild(beast)
+    }
+}
\ No newline at end of file
diff --git a/content_script/src/main/kotlin/helpers.kt b/content_script/src/main/kotlin/helpers.kt
new file mode 100644
index 0000000..4113c3d
--- /dev/null
+++ b/content_script/src/main/kotlin/helpers.kt
@@ -0,0 +1 @@
+external val browser: dynamic
\ No newline at end of file
diff --git a/gradle.properties b/gradle.properties
new file mode 100644
index 0000000..5711a98
--- /dev/null
+++ b/gradle.properties
@@ -0,0 +1 @@
+kotlin.incremental.js=false
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..6733908
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..3bffae5
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Sun Nov 19 14:32:19 CET 2017
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.3.1-bin.zip
diff --git a/gradlew b/gradlew
new file mode 100644
index 0000000..cccdd3d
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..f955316
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/icons/LICENSE b/icons/LICENSE
new file mode 100644
index 0000000..9a206f8
--- /dev/null
+++ b/icons/LICENSE
@@ -0,0 +1,4 @@
+
+The icon "beasts-32.png" is taken from the IconBeast Lite iconset, and used under the terms of its license (http://www.iconbeast.com/faq/), with a link back to the website: http://www.iconbeast.com/free/.
+
+The icon "beasts-48.png" is taken from Aha-Soft’s Free Retina iconset, and used under the terms of its license (http://www.aha-soft.com/free-icons/free-retina-icon-set/), with a link back to the website: http://www.aha-soft.com/.
diff --git a/icons/beasts-32-light.png b/icons/beasts-32-light.png
new file mode 100644
index 0000000..dbed714
Binary files /dev/null and b/icons/beasts-32-light.png differ
diff --git a/icons/beasts-32.png b/icons/beasts-32.png
new file mode 100644
index 0000000..89863cc
Binary files /dev/null and b/icons/beasts-32.png differ
diff --git a/icons/beasts-48.png b/icons/beasts-48.png
new file mode 100644
index 0000000..c3f0924
Binary files /dev/null and b/icons/beasts-48.png differ
diff --git a/manifest.json b/manifest.json
new file mode 100644
index 0000000..81f8865
--- /dev/null
+++ b/manifest.json
@@ -0,0 +1,33 @@
+{
+
+  "description": "Adds a browser action icon to the toolbar. Click the button to choose a beast. The active tab's body content is then replaced with a picture of the chosen beast. See https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Examples#beastify",
+  "manifest_version": 2,
+  "name": "Beastify",
+  "version": "1.0",
+  "homepage_url": "https://github.com/mdn/webextensions-examples/tree/master/beastify",
+  "icons": {
+    "48": "icons/beasts-48.png"
+  },
+
+  "permissions": [
+    "activeTab"
+  ],
+
+  "browser_action": {
+    "default_icon": "icons/beasts-32.png",
+    "theme_icons": [{
+        "light": "icons/beasts-32-light.png",
+        "dark": "icons/beasts-32.png",
+        "size": 32
+    }],
+    "default_title": "Beastify",
+    "default_popup": "popup/choose_beast.html"
+  },
+
+  "web_accessible_resources": [
+    "beasts/frog.jpg",
+    "beasts/turtle.jpg",
+    "beasts/snake.jpg"
+  ]
+
+}
diff --git a/popup/choose_beast.css b/popup/choose_beast.css
new file mode 100644
index 0000000..db4c5a5
--- /dev/null
+++ b/popup/choose_beast.css
@@ -0,0 +1,31 @@
+html, body {
+  width: 100px;
+}
+
+.hidden {
+  display: none;
+}
+
+.button {
+  margin: 3% auto;
+  padding: 4px;
+  text-align: center;
+  font-size: 1.5em;
+  cursor: pointer;
+}
+
+.beast:hover {
+  background-color: #CFF2F2;
+}
+
+.beast {
+  background-color: #E5F2F2;
+}
+
+.reset {
+  background-color: #FBFBC9;
+}
+
+.reset:hover {
+  background-color: #EAEA9D;
+}
diff --git a/popup/choose_beast.html b/popup/choose_beast.html
new file mode 100644
index 0000000..2d2e96a
--- /dev/null
+++ b/popup/choose_beast.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+
+<html>
+  <head>
+    <meta charset="utf-8">
+    <link rel="stylesheet" href="choose_beast.css"/>
+  </head>
+
+<body>
+  <div id="popup-content">
+    <div class="button beast">Frog</div>
+    <div class="button beast">Turtle</div>
+    <div class="button beast">Snake</div>
+    <div class="button reset">Reset</div>
+  </div>
+  <div id="error-content" class="hidden">
+    <p>Can't beastify this web page.</p><p>Try a different page.</p>
+  </div>
+  <script src="build/classes/kotlin/main/min/kotlin.js"></script>
+  <script src="build/classes/kotlin/main/min/popup.js"></script>
+</body>
+
+</html>
diff --git a/popup/choose_beast.js b/popup/choose_beast.js
new file mode 100644
index 0000000..8caac4c
--- /dev/null
+++ b/popup/choose_beast.js
@@ -0,0 +1,102 @@
+/**
+ * CSS to hide everything on the page,
+ * except for elements that have the "beastify-image" class.
+ */
+const hidePage = `body > :not(.beastify-image) {
+                    display: none;
+                  }`;
+
+/**
+ * Listen for clicks on the buttons, and send the appropriate message to
+ * the content script in the page.
+ */
+function listenForClicks() {
+    document.addEventListener("click", (e) => {
+
+        /**
+         * Given the name of a beast, get the URL to the corresponding image.
+         */
+        function beastNameToURL(beastName) {
+            switch (beastName) {
+                case "Frog":
+                    return browser.extension.getURL("beasts/frog.jpg");
+                case "Snake":
+                    return browser.extension.getURL("beasts/snake.jpg");
+                case "Turtle":
+                    return browser.extension.getURL("beasts/turtle.jpg");
+            }
+        }
+
+        /**
+         * Insert the page-hiding CSS into the active tab,
+         * then get the beast URL and
+         * send a "beastify" message to the content script in the active tab.
+         */
+        function beastify(tabs) {
+            browser.tabs.insertCSS({code: hidePage}).then(() => {
+                let url = beastNameToURL(e.target.textContent);
+                browser.tabs.sendMessage(tabs[0].id, {
+                    command: "beastify",
+                    beastURL: url
+                });
+            });
+        }
+
+        /**
+         * Remove the page-hiding CSS from the active tab,
+         * send a "reset" message to the content script in the active tab.
+         */
+        function reset(tabs) {
+            browser.tabs.removeCSS({code: hidePage}).then(() => {
+                browser.tabs.sendMessage(tabs[0].id, {
+                    command: "reset",
+                });
+            });
+        }
+
+        /**
+         * Just log the error to the console.
+         */
+        function reportError(error) {
+            console.error(`Could not beastify: ${error}`);
+        }
+
+        /**
+         * Get the active tab,
+         * then call "beastify()" or "reset()" as appropriate.
+         */
+        if (e.target.classList.contains("beast")) {
+            browser.tabs.query({active: true, currentWindow: true})
+                .then(beastify)
+                .catch(reportError);
+        }
+        else if (e.target.classList.contains("reset")) {
+            browser.tabs.query({active: true, currentWindow: true})
+                .then(reset)
+                .catch(reportError);
+        }
+    });
+}
+
+/**
+ * There was an error executing the script.
+ * Display the popup's error message, and hide the normal UI.
+ */
+function reportExecuteScriptError(error) {
+    document.querySelector("#popup-content").classList.add("hidden");
+    document.querySelector("#error-content").classList.remove("hidden");
+    console.error(`Failed to execute beastify content script: ${error.message}`);
+}
+
+/**
+ * When the popup loads, inject a content script into the active tab,
+ * and add a click handler.
+ * If we couldn't inject the script, handle the error.
+ */
+browser.tabs.executeScript({file: "/content_script/build/classes/kotlin/main/min/kotlin.js"})
+    .then(() => {
+        browser.tabs.executeScript({file: "/content_script/build/classes/kotlin/main/min/content_script.js"})
+            .then(listenForClicks)
+            .catch(reportExecuteScriptError);
+    })
+    .catch(reportExecuteScriptError);
diff --git a/popup/src/main/kotlin/helpers.kt b/popup/src/main/kotlin/helpers.kt
new file mode 100644
index 0000000..9efece3
--- /dev/null
+++ b/popup/src/main/kotlin/helpers.kt
@@ -0,0 +1,31 @@
+import kotlin.js.Promise
+
+external val browser: Browser
+
+external class Browser {
+    val tabs: Tabs
+    val extension: Extension
+}
+
+external class Tabs {
+    fun executeScript(def: ScriptDefinition) : Promise<List<Any>>
+    fun insertCSS(details: CssDetails): Promise<Unit>
+    fun removeCSS(details: CssDetails): Promise<Unit>
+    fun sendMessage(id: Int, any: Any): Any
+    fun query(info: QueryInfo) : Promise<Array<Tab>>
+}
+
+external class Extension {
+    fun getURL(s: String): String
+}
+
+class Tab(val id: Int)
+
+class ScriptDefinition(val file: String)
+class CssDetails(val code: String)
+class QueryInfo(active: Boolean, currentWindow: Boolean)
+
+external open class Object {
+}
+
+fun jsObject(init: dynamic.() -> Unit): dynamic = (Object()).apply(init)
\ No newline at end of file
diff --git a/popup/src/main/kotlin/popup.kt b/popup/src/main/kotlin/popup.kt
new file mode 100644
index 0000000..b374e01
--- /dev/null
+++ b/popup/src/main/kotlin/popup.kt
@@ -0,0 +1,76 @@
+import org.w3c.dom.Element
+import kotlin.browser.document
+
+const val hidePage = """
+    body > :not(.beastify-image) {
+        display: none;
+    }
+"""
+
+const val scriptPath = "/content_script/build/classes/kotlin/main/min"
+
+fun listenForClicks() {
+    document.addEventListener("click", { e ->
+
+        val target = e.target as Element
+
+        fun beastNameToURL(beastName: String) = when (beastName) {
+            "Frog" -> browser.extension.getURL("beasts/frog.jpg")
+            "Snake" -> browser.extension.getURL("beasts/snake.jpg")
+            "Turtle" -> browser.extension.getURL("beasts/turtle.jpg")
+            else -> null
+        }
+
+        fun beastify(tabs: Array<Tab>) {
+            browser.tabs.insertCSS(CssDetails(hidePage))
+                    .then({
+                        val url = beastNameToURL(target.textContent as String)
+                        browser.tabs.sendMessage(tabs[0].id, jsObject {
+                            command = "beastify"
+                            beastURL = url
+                        })
+                    })
+        }
+
+        fun reset(tabs: Array<Tab>) {
+            browser.tabs.removeCSS(CssDetails(hidePage))
+                    .then({
+                        browser.tabs.sendMessage(tabs[0].id, jsObject {
+                            command = "reset"
+                        })
+                    })
+        }
+
+        fun reportError(error: Any) {
+            console.error("Could not beastify: $error")
+        }
+
+
+        val callback = when {
+            target.classList.contains("beast") -> ::beastify
+            target.classList.contains("reset") -> ::reset
+            else -> return@addEventListener
+        }
+
+        browser.tabs.query(QueryInfo(active = true, currentWindow = true))
+                .then(callback)
+                .catch(::reportError)
+    })
+}
+
+fun reportExecuteScriptError(error: Throwable) {
+    document.querySelector("#popup-content")?.classList?.add("hidden")
+    document.querySelector("#error-content")?.classList?.remove("hidden")
+    console.error("Failed to execute beastify content script: ${error.message}")
+}
+
+
+fun main(args: Array<String>) {
+    browser.tabs.executeScript(ScriptDefinition("$scriptPath/kotlin.js"))
+            .then({
+                browser.tabs.executeScript(ScriptDefinition("$scriptPath/content_script.js"))
+                        .then({ listenForClicks() })
+            })
+            .catch(::reportExecuteScriptError)
+}
+
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..5a17def
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,3 @@
+rootProject.name = 'kt-beastify'
+
+include ':popup', ':content_script'