aside[data-type] {
    padding: 1rem;
    margin-bottom: 1rem;
    border-left: 4px solid #ccc;
}

aside[data-type="error"] { border-left-color: #dc3545; }
aside[data-type="success"] { border-left-color: #28a745; }
aside[data-type="warning"] { border-left-color: #ffc107; }
aside[data-type="info"] { border-left-color: #17a2b8; }