Improve layout responsiveness on narrow windows

Prevent horizontal overflow with overflow-x: hidden on body. Make the
gradient bar fill its container in focused mode (width: 100%;
min-width: 0) rather than holding a fixed minimum width.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bicorder-app/src/app.css

@@ -47,6 +47,7 @@ body {
   touch-action: manipulation;
   -webkit-tap-highlight-color: transparent;
   font-size: 16px;
+  overflow-x: hidden;
 }
 
 #app {

bicorder-app/src/components/AnalysisDisplay.svelte

@@ -214,6 +214,11 @@
     width: 100%;
   }
 
+  .gradient-row.focused .bar {
+    width: 100%;
+    min-width: 0;
+  }
+
   .term {
     text-align: center;
     font-size: 0.9rem;

bicorder-app/src/components/GradientSlider.svelte

@@ -189,6 +189,11 @@
     width: 100%;
   }
 
+  .gradient-row.focused .bar {
+    width: 100%;
+    min-width: 0;
+  }
+
   .term {
     text-align: center;
     font-size: 0.9rem;