jQuery Modal Dialog: Input fields cannot be interacted with using custom CSS theme

using a jQuery custom theme (version jquery-ui-1.11.3), and creating a modal dialog, the input fields cannot be interacted.

in jquery-ui.css, add fix as below:
.ui-widget {
font-family: Verdana,Arial,sans-serif;
font-size: 1.1em;
/* add by mye -start */
z-index: 9999;
position: relative;
/* add by mye – end */

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