title: problems with 'com.android.support:appcompat-v7.27.1.1' in the gradle file
body: <p>This is my dependencies file and there is an underlined red colored text on the  compile 'com.android.support:appcompat-v7.27.1.1'</p>
  
  <pre><code>apply plugin: 'com.android.application'
   android {
  compileSdkVersion 27
  defaultConfig {
      applicationId "com.abc.mcaproject"
      minSdkVersion 21
      targetSdkVersion 27
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  }
  
  dependencies {
  implementation fileTree(dir: 'libs', include: ['*.jar'])
  
  
  compile 'com.android.support:appcompat-v7.27.1.1'
  implementation 'com.android.support.constraint:constraint-layout:1.1.0'
  implementation 'com.google.firebase:firebase-database:11.6.0'
  implementation 'com.google.firebase:firebase-messaging:11.6.0'
  implementation 'com.google.firebase:firebase-auth:11.6.0'
  implementation 'com.google.firebase:firebase-storage:11.6.0'
  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'
  }
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>This because of this I am having problems changing themes in the styles.xml</p>