Make the layout of the mail viewer contents more consistent

Signed-off-by: Claudio Cambra <claudio.cambra@gmail.com>

src/mail/qml/MailViewer.qml

@@ -20,14 +20,25 @@ QQC2.Page {
     property string to
     property date dateTime
 
+    Kirigami.Theme.colorSet: Kirigami.Theme.View
+    Kirigami.Theme.inherit: false
+
+    padding: Kirigami.Units.largeSpacing * 2
+
+    background: Rectangle {
+        color: Kirigami.Theme.backgroundColor
+        property color borderColor: Kirigami.Theme.textColor
+        border.color: Qt.rgba(borderColor.r, borderColor.g, borderColor.b, 0.3)
+        radius: Kirigami.Units.largeSpacing
+    }
+
     header: QQC2.ToolBar {
-        padding: Kirigami.Units.largeSpacing
+        padding: root.padding
 
         Kirigami.Theme.inherit: false
         Kirigami.Theme.colorSet: Kirigami.Theme.View
 
         background: Item {
-            implicitHeight: 40
             Kirigami.Separator {
                 anchors {
                     left: parent.left
@@ -86,13 +97,12 @@ QQC2.Page {
     }
 
     footer: QQC2.ToolBar {
-        padding: Kirigami.Units.largeSpacing
+        padding: root.padding
 
         Kirigami.Theme.inherit: false
         Kirigami.Theme.colorSet: Kirigami.Theme.View
 
         background: Item {
-            implicitHeight: 40
             Kirigami.Separator {
                 anchors {
                     left: parent.left
@@ -125,13 +135,4 @@ QQC2.Page {
             }
         }
     }
-    Kirigami.Theme.colorSet: Kirigami.Theme.View
-    Kirigami.Theme.inherit: false
-
-    background: Rectangle {
-        color: Kirigami.Theme.backgroundColor
-        property color borderColor: Kirigami.Theme.textColor
-        border.color: Qt.rgba(borderColor.r, borderColor.g, borderColor.b, 0.3)
-        radius: 4
-    }
 }

src/mail/qml/mailpartview/MailPartModel.qml

@@ -77,9 +77,6 @@ DelegateModel {
                 left: parent.left
                 right: parent.right
                 top: parent.top
-                rightMargin: Kirigami.Units.largeSpacing
-                leftMargin: Kirigami.Units.largeSpacing
-                topMargin: Kirigami.Units.smallSpacing
             }
             spacing: Kirigami.Units.smallSpacing
 
@@ -106,7 +103,7 @@ DelegateModel {
                 id: partLoader
                 Layout.preferredHeight: item ? item.contentHeight : 0
                 Layout.maximumWidth: parent.width
-                width: parent.width
+                Layout.fillWidth: true
                 Binding {
                     target: partLoader.item
                     property: "searchString"

src/mail/qml/mailpartview/TextPart.qml

@@ -31,6 +31,7 @@ Item {
         background: Item {}
         readOnly: true
         textFormat: TextEdit.RichText
+        padding: 0
 
         anchors {
             top: parent.top