improve layout

app.py

@@ -1162,6 +1162,8 @@ def create_timeline_template():
             flex: 22%;
             min-width: 220px;
             padding-left: 8px; /* add small spacing from collapse arrow */
+            display: flex;
+            flex-direction: column;
         }
 
         .modality-filters {
@@ -1169,17 +1171,22 @@ def create_timeline_template():
             flex-wrap: wrap;
             gap: 0.25rem;
             margin-top: 0.2rem;
+            flex: 1;
         }
 
         .modality-buttons {
             display: flex;
             gap: 0.3rem;
             margin-top: 0.3rem;
+            margin-bottom: 0.5rem;
+            align-items: flex-end;
         }
 
         .task-group {
             flex: 78%;
             min-width: 520px;
+            display: flex;
+            flex-direction: column;
         }
 
         .task-filters {
@@ -1187,20 +1194,25 @@ def create_timeline_template():
             flex-wrap: wrap;
             gap: 0.25rem;
             margin-top: 0.2rem;
-            max-height: 140px;
-            overflow-y: auto;
+            flex: 1;
         }
 
         .task-buttons {
             display: flex;
             gap: 0.3rem;
             margin-top: 0.3rem;
+            margin-bottom: 0.5rem;
+            align-items: flex-end;
         }
 
         .btn-small {
-            padding: 0.2rem 0.4rem;
+            padding: 0.4rem 0.6rem;
             font-size: 0.65rem;
             margin-top: 0;
+            height: 32px;
+            display: flex;
+            align-items: center;
+            justify-content: center;
         }
 
         .modality-checkbox {