To disable resizing completely:
textarea {
resize: none;
}
To allow only vertical resizing:
textarea {
resize: vertical;
}
To allow only horizontal resizing:
textarea {
resize: horizontal;
}
Or you can limit size:
textarea {
max-width: 100px;
max-height: 100px;
}
To limit size to parents width and/or height:
textarea {
max-width: 100%;
max-height: 100%;
}