feat: refine Android UI with muted pastel expressive design

app/src/main/java/com/olavbg/javazone/ui/components/AnimatedDiagonalBackground.kt

@@ -0,0 +1,71 @@
+package com.olavbg.javazone.ui.components
+
+import androidx.compose.animation.core.RepeatMode
+import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.infiniteRepeatable
+import androidx.compose.animation.core.rememberInfiniteTransition
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.drawscope.clipPath
+
+/**
+ * Subtle JavaZone background: two calm tones separated by a slowly moving diagonal.
+ * Kept deliberately low contrast so foreground content remains the visual priority.
+ */
+@Composable
+fun AnimatedDiagonalBackground(
+    modifier: Modifier = Modifier,
+    content: @Composable () -> Unit,
+) {
+    val transition = rememberInfiniteTransition(label = "diagonal-background")
+    val sway by transition.animateFloat(
+        initialValue = -0.08f,
+        targetValue = 0.08f,
+        animationSpec = infiniteRepeatable(
+            animation = tween(durationMillis = 9000),
+            repeatMode = RepeatMode.Reverse,
+        ),
+        label = "diagonal-sway",
+    )
+
+    val firstTone = MaterialTheme.colorScheme.surfaceContainerLowest
+    val secondTone = MaterialTheme.colorScheme.surfaceContainerLow
+
+    Box(modifier = modifier) {
+        Canvas(modifier = Modifier.fillMaxSize()) {
+            val diagonalX = size.width * (0.52f + sway)
+
+            val firstPath = Path().apply {
+                moveTo(0f, 0f)
+                lineTo(diagonalX, 0f)
+                lineTo(0f, size.height)
+                close()
+            }
+            clipPath(firstPath) {
+                drawRect(color = firstTone)
+            }
+
+            val secondPath = Path().apply {
+                moveTo(diagonalX, 0f)
+                lineTo(size.width, 0f)
+                lineTo(size.width, size.height)
+                lineTo(0f, size.height)
+                close()
+            }
+            clipPath(secondPath) {
+                drawRect(color = secondTone)
+            }
+        }
+
+        Box(modifier = Modifier.fillMaxSize()) {
+            content()
+        }
+    }
+}

app/src/main/java/com/olavbg/javazone/ui/theme/Color.kt

@@ -2,27 +2,33 @@ package com.olavbg.javazone.ui.theme
 
 import androidx.compose.ui.graphics.Color
 
-val FreshGreen = Color(0xFF00E676)
-val DeepBlue = Color(0xFF1E3A8A)
-val DarkBackground = Color(0xFF0F172A) // Rich slate navy background
-val DarkSurface = Color(0xFF1E293B)    // Elevated slate card surface
-val DarkSurfaceVariant = Color(0xFF334155) // Border/Header variant
-val DarkOnSurface = Color(0xFFF8FAFC)
+// JavaZone palette: muted pastels over calm, dark neutrals.
+val FreshGreen = Color(0xFF9DB8A5)
+val DeepBlue = Color(0xFF667B9B)
+val DarkBackground = Color(0xFF17191E)
+val DarkSurface = Color(0xE6202329) // Slight translucency lets the diagonal identity show through.
+val DarkSurfaceVariant = Color(0xD930343C)
+val DarkOnSurface = Color(0xFFF1F0ED)
 
-val JavaBlue = Color(0xFF2563EB)
-val JavaOrange = Color(0xFFF97316)
+val JavaBlue = Color(0xFF8FA9C7)
+val JavaOrange = Color(0xFFD2A39A)
 
-val WorkshopPurple = Color(0xFFA855F7)
-val LightningAmber = Color(0xFFF59E0B)
-val PresentationBlue = Color(0xFF60A5FA) // Lighter blue for better contrast
+val WorkshopPurple = Color(0xFFB2A1C7)
+val LightningAmber = Color(0xFFD1B17D)
+val PresentationBlue = Color(0xFF8FA9C7)
 
 val RoomAccentColors = listOf(
-    Color(0xFF38BDF8),
-    Color(0xFF34D399),
-    Color(0xFFFB923C),
-    Color(0xFFE879F9),
-    Color(0xFFF87171),
-    Color(0xFF4ADE80),
-    Color(0xFFFBBF24),
-    Color(0xFF60A5FA)
+    Color(0xFF8FA9C7),
+    Color(0xFF9DB8A5),
+    Color(0xFFD2A39A),
+    Color(0xFFB2A1C7),
+    Color(0xFFC59A9A),
+    Color(0xFFA7B99A),
+    Color(0xFFD0B783),
+    Color(0xFF9AA9BD)
 )
+
+val LightBackground = Color(0xFFF2F0EC)
+val LightSurface = Color(0xEAFAF9F6)
+val LightSurfaceVariant = Color(0xDDE3E1DD)
+val LightOnSurface = Color(0xFF202228)

app/src/main/java/com/olavbg/javazone/ui/theme/Shape.kt

@@ -4,9 +4,10 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.Shapes
 import androidx.compose.ui.unit.dp
 
+// More restrained geometry: cleaner and straighter than the previous expressive radii.
 val Shapes = Shapes(
-    small = RoundedCornerShape(8.dp),
-    medium = RoundedCornerShape(16.dp),
-    large = RoundedCornerShape(24.dp),
-    extraLarge = RoundedCornerShape(32.dp)
+    small = RoundedCornerShape(6.dp),
+    medium = RoundedCornerShape(10.dp),
+    large = RoundedCornerShape(14.dp),
+    extraLarge = RoundedCornerShape(18.dp)
 )

app/src/main/java/com/olavbg/javazone/ui/theme/Theme.kt

@@ -10,39 +10,48 @@ import androidx.compose.material3.lightColorScheme
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
+import com.olavbg.javazone.ui.components.AnimatedDiagonalBackground
 
 private val DarkColorScheme = darkColorScheme(
     primary = FreshGreen,
     secondary = JavaBlue,
     tertiary = JavaOrange,
-    background = DarkBackground,
+    background = Color.Transparent,
     surface = DarkSurface,
-    onPrimary = Color.Black,
-    onSecondary = Color.White,
-    onTertiary = Color.Black,
+    surfaceContainerLowest = Color(0xFF15171B),
+    surfaceContainerLow = Color(0xFF1B1E23),
+    surfaceContainer = DarkSurface,
+    surfaceContainerHigh = Color(0xFF282C33),
+    onPrimary = Color(0xFF17201A),
+    onSecondary = Color(0xFF17202A),
+    onTertiary = Color(0xFF271A18),
     onBackground = DarkOnSurface,
     onSurface = DarkOnSurface,
     surfaceVariant = DarkSurfaceVariant,
-    onSurfaceVariant = Color(0xFF94A3B8),
-    secondaryContainer = Color(0xFF1E3A8A),
-    onSecondaryContainer = Color(0xFFDBEAFE),
+    onSurfaceVariant = Color(0xFFB7B9BD),
+    secondaryContainer = Color(0xFF344253),
+    onSecondaryContainer = Color(0xFFDCE5EF),
 )
 
 private val LightColorScheme = lightColorScheme(
-    primary = DeepBlue,
-    secondary = FreshGreen,
-    tertiary = JavaOrange,
-    background = Color(0xFFF1F5F9),
-    surface = Color.White,
+    primary = Color(0xFF536B5B),
+    secondary = Color(0xFF58718F),
+    tertiary = Color(0xFF986B62),
+    background = Color.Transparent,
+    surface = LightSurface,
+    surfaceContainerLowest = Color(0xFFECEAE5),
+    surfaceContainerLow = Color(0xFFF0EEE9),
+    surfaceContainer = LightSurface,
+    surfaceContainerHigh = Color(0xFFE7E5E0),
     onPrimary = Color.White,
-    onSecondary = Color.Black,
-    onTertiary = Color.Black,
-    onBackground = Color(0xFF0F172A),
-    onSurface = Color(0xFF0F172A),
-    surfaceVariant = Color(0xFFE2E8F0),
-    onSurfaceVariant = Color(0xFF64748B),
-    secondaryContainer = Color(0xFFDBEAFE),
-    onSecondaryContainer = Color(0xFF1E3A8A),
+    onSecondary = Color.White,
+    onTertiary = Color.White,
+    onBackground = LightOnSurface,
+    onSurface = LightOnSurface,
+    surfaceVariant = LightSurfaceVariant,
+    onSurfaceVariant = Color(0xFF5E6064),
+    secondaryContainer = Color(0xFFDCE5EF),
+    onSecondaryContainer = Color(0xFF30465D),
 )
 
 @Composable
@@ -56,7 +65,6 @@ fun JavaZoneTheme(
             val context = LocalContext.current
             if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
         }
-
         darkTheme -> DarkColorScheme
         else -> LightColorScheme
     }
@@ -65,6 +73,9 @@ fun JavaZoneTheme(
         colorScheme = colorScheme,
         typography = Typography,
         shapes = Shapes,
-        content = content
-    )
-}
+    ) {
+        AnimatedDiagonalBackground {
+            content()
+        }
+    }
+}