Improve handling of responsive layouts

panel/dist/css/card.css

@@ -1,48 +1,56 @@
 :host(.card) {
-  border: 1px solid rgba(0,0,0,.125);
-  border-radius: 0.25rem;
+    border: 1px solid rgba(0,0,0,.125);
+    border-radius: 0.25rem;
 }
 
 :host(.accordion) {
-  border: 1px solid rgba(0,0,0,.125);
+    border: 1px solid rgba(0,0,0,.125);
 }
 
 .card-header {
-  align-items: center;
-  background-color: rgba(0, 0, 0, 0.03);
-  border-radius: 0.25rem;
-  display: inline-flex;
-  justify-content: start;
-  width: 100%;
+    align-items: center;
+    background-color: rgba(0, 0, 0, 0.03);
+    border: 1px solid;
+    border-radius: 0.25rem;
+    display: inline-flex;
+    justify-content: start;
+    position: sticky;
+    left: 0;
+    width: 100%;
 }
 
 .accordion-header {
-  align-items: center;
-  background-color: rgba(0, 0, 0, 0.03);
-  border-radius: 0;
-  display: flex;
-  justify-content: start;
-  width: 100%;
+    align-items: center;
+    background-color: rgba(0, 0, 0, 0.03);
+    border: 1px solid;
+    border-radius: 0;
+    display: flex;
+    justify-content: start;
+    position: sticky;
+    left: 0;
+    width: 100%;
 }
 
 .card-button {
-  background-color: transparent;
-  margin-left: 0.5em;
-  margin-right: 0.5em;
+    background-color: transparent;
+    margin-left: 0.5em;
+    margin-right: 0.5em;
 }
 
 .card-header-row {
-  position: relative !important;
+    margin-bottom: auto;
+    margin-top: auto;
+    position: relative !important;
 }
 
 .card-title {
-  align-items: center;
-  font-size: 1.4em;
-  font-weight: bold;
-  overflow-wrap: break-word;
+    align-items: center;
+    font-size: 1.4em;
+    font-weight: bold;
+    overflow-wrap: break-word;
 }
 
 .card-header-row > .bk {
-  overflow-wrap: break-word;
-  text-align: center;
+    overflow-wrap: break-word;
+    text-align: center;
 }

panel/layout/base.py

@@ -72,11 +72,10 @@ def __repr__(self, depth: int = 0, max_depth: int = 10) -> str:
     # Callback API
     #----------------------------------------------------------------
 
-    def _init_params(self) -> Dict[str, Any]:
-        return {
-            p: v for p, v in self.param.values().items()
-            if v is not None and p != 'objects'
-        }
+    def _process_param_change(self, params: Dict[str, Any]) -> Dict[str, Any]:
+        if ('styles' in params or 'sizing_mode' in params) and self.sizing_mode in ('stretch_width', 'stretch_both'):
+            params['styles'] = dict(params.get('styles', {}), **{'overflow-x': 'auto'})
+        return super()._process_param_change(params)
 
     def _update_model(
         self, events: Dict[str, param.parameterized.Event], msg: Dict[str, Any],
@@ -86,6 +85,10 @@ def _update_model(
         inverse = {v: k for k, v in self._property_mapping.items() if v is not None}
         preprocess = any(inverse.get(k, k) in self._preprocess_params for k in msg)
 
+        # ALERT: Find a better way to handle this
+        if 'styles' in msg and root is model and 'overflow-x' in msg['styles']:
+            del msg['styles']['overflow-x']
+
         obj_key = self._property_mapping['objects']
         if obj_key in msg:
             old = events['objects'].old
@@ -159,6 +162,16 @@ def _get_model(
     # Public API
     #----------------------------------------------------------------
 
+    def get_root(
+        self, doc: Optional[Document] = None, comm: Optional[Comm] = None,
+        preprocess: bool = True
+    ) -> Model:
+        root = super().get_root(doc, comm, preprocess)
+        # ALERT: Find a better way to handle this
+        if hasattr(root, 'styles') and 'overflow-x' in root.styles:
+            del root.styles['overflow-x']
+        return root
+
     def select(self, selector=None):
         """
         Iterates over the Viewable and any potential children in the

panel/layout/card.py

@@ -108,7 +108,7 @@ def _update_header(self, *events):
         from ..pane import HTML, panel
         if self.header is None:
             params = {
-                'object': '%s' % (self.title or "​"),
+                'object': f'<h3>{self.title}</h3>' if self.title else "&#8203;",
                 'css_classes': self.title_css_classes,
                 'margin': (5, 0)
             }

panel/tests/layout/test_accordion.py

@@ -50,9 +50,9 @@ def test_accordion_constructor(document, comm):
     assert all(isinstance(c, Card) for c in model.children)
     card1, card2 = model.children
 
-    assert card1.children[0].children[0].text == 'Div1'
+    assert card1.children[0].children[0].text == '<h3>Div1</h3>'
     assert card1.children[1] is div1
-    assert card2.children[0].children[0].text == 'Div2'
+    assert card2.children[0].children[0].text == '<h3>Div2</h3>'
     assert card2.children[1] is div2
 
 
@@ -69,9 +69,11 @@ def test_accordion_implicit_constructor(document, comm):
     assert all(isinstance(c, Card) for c in model.children)
     card1, card2 = model.children
 
-    assert card1.children[0].children[0].text == p1.name == 'Div1'
+    assert p1.name == 'Div1'
+    assert card1.children[0].children[0].text == '<h3>Div1</h3>'
     assert card1.children[1] is div1
-    assert card2.children[0].children[0].text == p2.name == 'Div2'
+    assert p2.name == 'Div2'
+    assert card2.children[0].children[0].text == '<h3>Div2</h3>'
     assert card2.children[1] is div2
 
 
@@ -88,9 +90,9 @@ def test_accordion_constructor_with_named_objects(document, comm):
     assert all(isinstance(c, Card) for c in model.children)
     card1, card2 = model.children
 
-    assert card1.children[0].children[0].text == 'Tab1'
+    assert card1.children[0].children[0].text == '<h3>Tab1</h3>'
     assert card1.children[1] is div1
-    assert card2.children[0].children[0].text == 'Tab2'
+    assert card2.children[0].children[0].text == '<h3>Tab2</h3>'
     assert card2.children[1] is div2
 
 

panel/tests/layout/test_card.py

@@ -46,14 +46,14 @@ def test_card_get_root_title(document, comm):
 
     assert isinstance(model, CardModel)
     assert model.children == [header, div1, div2]
-    assert header.children[0].text == "Test"
+    assert header.children[0].text == '<h3>Test</h3>'
 
     div3 = Div()
     layout.header = div3
     assert header.children[0] is div3
 
     layout.header = None
-    assert header.children[0].text == "Test"
+    assert header.children[0].text == '<h3>Test</h3>'
 
 
 def test_card_get_root_header(document, comm):

panel/theme/css/bootstrap.css

@@ -79,8 +79,8 @@ button.accordion-header {
 
 :host(.card-title) h1, :host(.card-title) h2, :host(.card-title) h3,
 :host(.card-title) h4, :host(.card-title) h5, :host(.card-title) h6 {
-    margin-block-end: 0;
-    margin-block-start: 0;
+    margin-block-end: 0.2em;
+    margin-block-start: 0.2em;
 }
 
 /* Tabs styling */

panel/theme/css/fast.css

@@ -156,8 +156,8 @@ canvas, img {
 
 :host(.card-title) h1, :host(.card-title) h2, :host(.card-title) h3,
 :host(.card-title) h4, :host(.card-title) h5, :host(.card-title) h6 {
-    margin-block-end: 0;
-    margin-block-start: 0;
+    margin-block-end: 0.2em;
+    margin-block-start: 0.2em;
 }
 
 /* Tabs */

panel/theme/css/material.css

@@ -47,8 +47,8 @@ button.mdc-button.mdc-card-button {
 
 :host(.card-title) h1, :host(.card-title) h2, :host(.card-title) h3,
 :host(.card-title) h4, :host(.card-title) h5, :host(.card-title) h6 {
-    margin-block-end: 0;
-    margin-block-start: 0;
+    margin-block-end: 0.2em;
+    margin-block-start: 0.2em;
 }
 
 /* Tabs styling */

panel/theme/css/native.css

@@ -26,3 +26,9 @@
     color: var(--surface-text-color);
     background-color: var(--surface-color);
 }
+
+:host(.card-title) h1, :host(.card-title) h2, :host(.card-title) h3,
+:host(.card-title) h4, :host(.card-title) h5, :host(.card-title) h6 {
+    margin-block-end: 0.2em;
+    margin-block-start: 0.2em;
+}