Action buttons on cards are abnormally sized

问题

I'm using the Bot framework Nodejs SDK to send a Hero card to present the user with a question and 3 options.

In the webchat channel, it would be like this:

var card = new builder.HeroCard(session)
.title("Please chose from below options:")
.buttons([
    builder.CardAction.imBack(session, "A green shirt", "A green shirt"),
    builder.CardAction.imBack(session, "A blue shirt", "A blue shirt"),
    builder.CardAction.imBack(session, "A red shirt", "A red shirt")
])

var msg = new builder.Message(session).attachments([card]);
builder.Prompts.text(session, msg);

The chat screen does display the options in the form of buttons but the size seems to be off.

How do I modify the code to render the buttons in appropriate sizes, side by side?

来源：https://stackoverflow.com/questions/53143997/action-buttons-on-cards-are-abnormally-sized