Twitter Itself: Stars Not Hearts

BetterTwitter.css

/* Replace the heart with a star. */
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconContainer div div,
button.ProfileTweet-actionButton.js-actionFavorite div.IconContainer div div {
    background-image: none !important;
}
    /* Full star. */
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconContainer div div:after,
button.ProfileTweet-actionButton.js-actionFavorite div.IconContainer div div:after {
    font-family: rosettaicons;
    content: "\f147";
}
    /* Boxed star. */
div.stream-item-activity-line-notification b span.Icon--heartBadge:before, p.social-proof
span.Icon--heartBadge:before, div.WebToast-imageBox span.Icon--heartBadge:before {
    font-family: rosettaicons;
    content: "\f001";
}
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconContainer div div,
button.ProfileTweet-actionButton.js-actionFavorite div.IconContainer div div{
    padding-top: 16px;
}

/* Change the color from red to yellow. */
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconTextContainer,
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconContainer,
button.ProfileTweet-actionButton.js-actionFavorite:hover,
div.ProfileTweet-action--favorite div.IconTextContainer span span:hover,
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconContainer div,
button.ProfileTweet-actionButtonUndo.js-actionFavorite div.IconContainer div div,
div.stream-item-activity-line-notification b span.Icon--heartBadge:before, p.social-proof
span.Icon--heartBadge:before, div.WebToast-imageBox span.Icon--heartBadge:before {
    color: #FAC10E;
}