input 100% with by Vladimir Starkov @matmuchrapna

HTML

<div class="input_wrap">
    <input type="text" />
</div>

CSS

/*
 * input 100% with by Vladimir Starkov @matmuchrapna
 */

div {
    padding: 6px 17px; /* equal to negative input's margin for mimic normal `div` box-sizing */

    /* demo only customizations */    
    background: red;
}

/**
 * input 100% with by Vladimir Starkov @matmuchrapna
 */

input {
    width: 100%; /* force to expand to container's width */ 
    height:40px;
    border: 7px solid #DFDFDF;  
    padding: 0 10px;
    margin: 0 -17px; /* negative margin = border-width + horizontal padding */ 
    
    /* demo only customizations */
    border-radius: 14px;
    box-shadow: 0 0 5px green inset;
}