Custom CSS errors

Shortcodes Ultimate is putting exclamation marks against three of the custom CSS I’m using. I’ve marked them with ***.

a.su-button.su-button-style-default {
 border: 0 !important; ***
}

.su-button span {
text-transform: none !important;
font-family: Oswald, Arial, sans-serif !important;
font-size: 14px !important;
font-weight:normal;
text-align:center;
background-color: transparent;
border: none !important;
}

.su-button span:hover {
 background: #28ac86; !important; ***
 border: none !important; ***
}

Please could you tell me what I’m doing wrong here and how to correct it.

Thank you.

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