diff --git a/StackLayoutManager/build.gradle b/StackLayoutManager/build.gradle
index 598d599..cda35ed 100644
--- a/StackLayoutManager/build.gradle
+++ b/StackLayoutManager/build.gradle
@@ -3,13 +3,13 @@ apply plugin: 'kotlin-android'
 apply plugin: 'com.novoda.bintray-release'
 
 android {
-    compileSdkVersion 27
+    compileSdkVersion 28
 
     defaultConfig {
         minSdkVersion 14
-        targetSdkVersion 27
-        versionCode 6
-        versionName "1.0.5"
+        targetSdkVersion 28
+        versionCode 7
+        versionName "1.0.6"
 
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
 
@@ -30,7 +30,7 @@ android {
 dependencies {
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-    implementation 'com.android.support:recyclerview-v7:27.1.1'
+    implementation 'com.android.support:recyclerview-v7:28.0.0'
 }
 repositories {
     mavenCentral()
@@ -46,7 +46,7 @@ publish{
     userOrg = 'jinliancheng120'
     groupId = 'com.littlemango'
     artifactId = 'stacklayoutmanager'
-    publishVersion = '1.0.5'
+    publishVersion = '1.0.6'
     desc = 'A RecyclerView.LayoutManager implementation which provides functionality to show a group of stack view.'
     website = 'https://github.com/LittleMango/StackLayoutManager'
     licences = ['MIT']
diff --git a/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/DefaultAnimation.kt b/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/DefaultAnimation.kt
index 9742e9e..d8b0b81 100644
--- a/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/DefaultAnimation.kt
+++ b/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/DefaultAnimation.kt
@@ -2,6 +2,7 @@ package com.littlemango.stacklayoutmanager
 
 import android.view.View
 import com.littlemango.stacklayoutmanager.StackLayoutManager.ScrollOrientation
+import kotlin.math.pow
 
 class DefaultAnimation(scrollOrientation: ScrollOrientation, visibleCount: Int) : StackAnimation(scrollOrientation, visibleCount) {
 
@@ -72,8 +73,8 @@ class DefaultAnimation(scrollOrientation: ScrollOrientation, visibleCount: Int)
             scale = 1 - ((1 - mOutScale) * firstMovePercent)
             rotation = mOutRotation * firstMovePercent
         } else {
-            val minScale = (Math.pow(mScale.toDouble(), position.toDouble())).toFloat()
-            val maxScale = (Math.pow(mScale.toDouble(), (position - 1).toDouble())).toFloat()
+            val minScale = (mScale.toDouble().pow(position.toDouble())).toFloat()
+            val maxScale = (mScale.toDouble().pow((position - 1).toDouble())).toFloat()
             scale = minScale + (maxScale - minScale) * firstMovePercent
             //只对最后一个 item 做透明度变化
             if (position == mVisibleCount) {
diff --git a/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/StackLayoutManager.kt b/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/StackLayoutManager.kt
index 5eef721..5c5ae25 100644
--- a/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/StackLayoutManager.kt
+++ b/StackLayoutManager/src/main/java/com/littlemango/stacklayoutmanager/StackLayoutManager.kt
@@ -6,6 +6,8 @@ import android.support.v7.widget.RecyclerView.SCROLL_STATE_DRAGGING
 import android.support.v7.widget.RecyclerView.SCROLL_STATE_IDLE
 import android.view.View
 import android.view.ViewGroup
+import kotlin.math.max
+import kotlin.math.min
 
 class StackLayoutManager(scrollOrientation: ScrollOrientation,
                           visibleCount: Int,
@@ -427,8 +429,8 @@ class StackLayoutManager(scrollOrientation: ScrollOrientation,
 
     private fun getValidOffset(expectOffset: Int): Int {
         return when(mScrollOrientation) {
-            ScrollOrientation.RIGHT_TO_LEFT, ScrollOrientation.LEFT_TO_RIGHT -> Math.max(Math.min(width * (itemCount - 1), expectOffset), 0)
-            else -> Math.max(Math.min(height * (itemCount - 1), expectOffset), 0)
+            ScrollOrientation.RIGHT_TO_LEFT, ScrollOrientation.LEFT_TO_RIGHT -> max(min(width * (itemCount - 1), expectOffset), 0)
+            else -> max(min(height * (itemCount - 1), expectOffset), 0)
         }
     }
 
diff --git a/sample/build.gradle b/sample/build.gradle
index eff7b48..6989aaf 100644
--- a/sample/build.gradle
+++ b/sample/build.gradle
@@ -5,13 +5,13 @@ apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-android-extensions'
 
 android {
-    compileSdkVersion 27
+    compileSdkVersion 28
     defaultConfig {
         applicationId "com.littlemango.stacklayoutmanagermaster"
         minSdkVersion 19
-        targetSdkVersion 27
-        versionCode 6
-        versionName "1.0.5"
+        targetSdkVersion 28
+        versionCode 7
+        versionName "1.0.6"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     buildTypes {
@@ -22,19 +22,19 @@ android {
     }
 }
 
-ext.kotlin_version = '1.2.60'
+ext.kotlin_version = '1.3.50'
 
 dependencies {
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-    implementation 'com.android.support:appcompat-v7:27.1.1'
+    implementation 'com.android.support:appcompat-v7:28.0.0'
     implementation 'com.android.support.constraint:constraint-layout:1.1.3'
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'com.android.support.test:runner:1.0.2'
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
-    implementation 'com.android.support:recyclerview-v7:27.1.1'
-    implementation 'com.android.support:cardview-v7:27.1.1'
+    implementation 'com.android.support:recyclerview-v7:28.0.0'
+    implementation 'com.android.support:cardview-v7:28.0.0'
     implementation project(':StackLayoutManager')
     implementation 'com.afollestad.material-dialogs:core:0.9.6.0'
-    implementation 'com.android.support:design:27.1.1'
+    implementation 'com.android.support:design:28.0.0'
 }