Collapse

As we know cardlayout don't have collapsable property as that of boxLayout. But as per your requirement you can try below code, feel free to modify according to you. This is a custom collapsable cardlayout.

a!localVariables(
  local!isOpen: true,
  {
    a!cardLayout(
      contents: a!cardLayout(
        contents: {
          a!sideBySideLayout(
            items: {
              a!sideBySideItem(
                item: a!richTextDisplayField(
                  labelPosition: "COLLAPSED",
                  value: {
                    a!richTextItem(text: "Attachments", size: "MEDIUM")
                  }
                )
              ),
              a!sideBySideItem(
                item: a!buttonArrayLayout(
                  buttons: {
                    a!buttonWidget(
                      icon: if(
                        local!isOpen,
                        "angle-down-bold",
                        "angle-right-bold"
                      ),
                      saveInto: a!save(local!isOpen, not(local!isOpen)),
                      size: "SMALL",
                      style: "LINK"
                    )
                  },
                  align: "END",
                  marginAbove: "NONE",
                  marginBelow: "NONE"
                ),
                width: "MINIMIZE"
              )
            },
            alignVertical: "MIDDLE"
          )
        },
        style: "STANDARD",
        showBorder: false,
        showShadow: false,
        decorativeBarPosition: "END",
        decorativeBarColor: "#F0F0F0"
      ),
      style: "STANDARD",
      padding: "NONE",
      marginBelow: if(local!isOpen, "NONE", "STANDARD"),
      showShadow: true,
      decorativeBarPosition: "TOP",
      decorativeBarColor: "ACCENT"
    ),
    a!columnsLayout(
      columns: {
        a!columnLayout(width: "EXTRA_NARROW"),
        a!columnLayout(
          contents: {
            a!cardLayout(
              contents: a!richTextDisplayField(
                value: a!richTextBulletedList(
                  items: a!richTextListItem(
                    text: {
                      a!richTextItem(text: "Document 1"),
                      char(10),
                      char(10),
                      a!richTextItem(text: "Document 2"),
                      char(10),
                      char(10),
                      a!richTextItem(text: "Document 3")
                    }
                  )
                )
              ),
              padding: "NONE",
              showBorder: false,
              showShadow: false,
              decorativeBarPosition: "START",
              decorativeBarColor: "ACCENT"
            )
          }
        )
      },
      showWhen: local!isOpen,
      marginBelow: "STANDARD"
    )
  }
)

Thank you stefen

But I can not share my code.

That's why I did not insert here