Why my table header disappearing when adding display table

Question

When I add display: table in the .data-container class in order to make the width of the table fully fit the container, the table header disappears. I want the header to show, as well as the width for the header and the table to be 100%. I'm not sure how to fix this issue. I've tried a couple things but only one or the other works.

I have the following table:

<table class="table-container data-container">
    <thead class="header-container">
      <tr class="inner-headers">
        <th class="header-content">Question</th>
        <th class="header-content">Criteria</th>
        <th class="header-content">Edit</th>
        <th class="header-content">Delete</th>
      </tr>
    </thead>
</table>

This is my css:

.table-container {
    flex: 1;
    box-sizing: border-box;
    border-radius: 4px;
    color: rgba(0, 0, 0, 0.87);
    font-family: "Roboto", "Helvetica", "Arial", sans-serif;
    font-weight: 400;
    font-size: 0.875rem;
    line-height: 1.43;
    letter-spacing: 0.01071em;
    outline: none;
    display: flex;
    flex-direction: column;
    border-spacing: 0;
    border-collapse: collapse;
    text-align: left;
}
.data-container {
    position: relative;
    -webkit-box-flex: 1;
    flex-grow: 1;
    flex-direction: column;
    overflow: hidden;
    width: 100%;
    display: table;
}
.header-container {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    overflow: hidden;
    display: flex;
    -webkit-box-align: center;
    align-items: center;
    border-top-left-radius: 4px;
    border-top-right-radius: 4px;
}
.inner-headers {
    transform: translate3d(0px, 0px, 0px);
    display: flex;
    -webkit-box-align: center;
    align-items: center;
}
.header-content {
    position: relative;
    display: flex;
    -webkit-box-align: center;
    align-items: center;
    -webkit-tap-highlight-color: transparent;
    padding: 0 10px;
    box-sizing: border-box;
    flex: 1;
    white-space: nowrap;
    text-overflow: ellipsis;
    overflow: hidden;
}

Answer 1

It is difficult to know what you want to achieve from looking at the CSS code. Most of that CSS is not necessary. However, the HTML code makes it clearer.

Set table-layout: fixed; for equal width columns and width: 100%; on the table-container class and the rest of the CSS is not necessary.

The data-container class is not necessary.

 .table-container { border: solid 2px green; border-radius: 4px; width: 100%; table-layout: fixed; }.header-container { border: solid 2px orange; }.inner-headers { border: solid 2px blue; }.header-content { border: solid 2px red; border-radius: 4px; }

 <table class="table-container"> <thead class="header-container"> <tr class="inner-headers"> <th class="header-content">Question</th> <th class="header-content">Criteria</th> <th class="header-content">Edit</th> <th class="header-content">Delete</th> </tr> </thead> </table>