h1 { font-family: sans-serif; padding: 10px; color: yellow; } input { font-size: 24px; } .main { border: blue solid thick; padding: 10px; width: 520px; background-color: #6666ff; } .display { font-family: Courier, monospace; font-size: 32px; border: black solid thin; padding: 10px; margin: 10px; width: 340px; background-color: #ffffcc; } .key_block { padding: 10px; }