Update Main-screen and add PSEActivity

app/src/main/java/com/schoolapp/cleverclass/PSEActivity.kt

@@ -0,0 +1,67 @@
+package com.schoolapp.cleverclass
+
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.ArrowBack
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.Font
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import com.schoolapp.cleverclass.ui.theme.CleverClassTheme
+
+class PSEActivity : ComponentActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            CleverClassTheme {
+                Surface(modifier = Modifier.fillMaxSize(),
+                    color = MaterialTheme.colorScheme.background) {
+                    PSEContent(activity = this)
+                }
+            }
+        }
+    }
+}
+
+// Content of PSE
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun PSEContent(activity: ComponentActivity){
+    Column() {
+        TopAppBar(
+            colors = TopAppBarDefaults.centerAlignedTopAppBarColors(MaterialTheme.colorScheme.background),
+            title = {
+                Text(text = "Periodensystem",
+                    fontFamily = FontFamily(Font(R.font.arlrdbd, FontWeight.Normal))
+                )
+            },
+            navigationIcon = {
+                IconButton(onClick = { activity.finish() }) {
+                    Icon(
+                        imageVector = Icons.Filled.ArrowBack,
+                        contentDescription = null
+                    )
+                }
+            },
+            modifier = Modifier.fillMaxWidth()
+        )
+
+        Column() {
+
+        }
+    }
+}