How to allow application to run on Lollipop 5.0 and above versions?

Question

Android

I want to install the minimum version to run the application - Lollipop 5.0. How to properly configure everything so that the application runs without errors on all higher versions? Now the compiler swears at Material features. Need to change buildToolsVersion?

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion '26.0.2'
    defaultConfig {
        applicationId "com.ralpalette.ral"
        minSdkVersion 21
        targetSdkVersion 21
        versionCode 1
        versionName "1.0.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:21.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'

    //Add Library
    compile 'com.github.ceryle:SegmentedButton:v1.2.2'
    compile 'com.google.code.gson:gson:2.4'
}

Answer 1

Set target and compile 26.