CSS Border doubling with flex - html

Question

I have a piece of CSS I am working with. Whenever I add the "display: flex" property to .student, the border suddenly doubles. I need the flex property because I want the text to be centered vertically next to the image inside of the .student table data cell. How can I get rid of this pesky double border? The double border goes away whenever I remove the display:flex property, but then the text is no longer vertically next to the image. I've tried whitespace, border collapse, and several others without any luck.
Codepin: https://codepen.io/dansbyt/pen/dyvoejG?editors=1100
CSS:
/* ------------{GRADEBOOK}------------ */
.gradebook {
position: absolute;
top: 60px; left: 0;
width: 100vw; height: calc(100vh - 126px);
overflow-y: scroll;
box-sizing: border-box;}
/* Table styling*/
table {table-layout: fixed; border-collapse: collapse;}
/* Table heading styling */
thead th {
height: 60px; width: 100px;
top: 0; z-index: 2;
position: -webkit-sticky; position: sticky;
border-right: 1px solid gray;
background-color: white;}
thead th:first-child {left: 0; z-index: 10;}
th {
padding: 10px 16px;
text-align: left;
font-weight: normal;
color: gray}
table .duedate {font-size: 14px; margin-bottom: 8px}
table .title {font-size: 18px; color: #5B7042}
/* Table data styling */
td {
text-align: center;
border: 1px solid gray;
background-color: white}
td.late{background-color: #EA5D6B}
td input {
text-align: center;
padding: 4px; margin: 0;
width: 114px;
border: none;}
/* Student Name styling */
.student {
padding: 6px;
box-sizing: border-box;
display: flex;
align-items: center}
.pic{
display: inline-block;
width: 25px;
clip-path: circle();
margin-right: 10px;}
.pic img{display: none}
/* ------------{CONTROLS}------------ */
.controls {
display: flex;
position: absolute;
bottom: 10px; left: 0;
width: 100vw; height: 56px;
border-top: 1px solid #DDDDDD}
HTML:
<link rel="stylesheet" href="../style.css">
<div class='gradebook'>
<table>
<thead>
<tr>
<th style='width: 200px'></th>
<th>
<div class='duedate'>Due Oct 08</div>
<div class='title'>Mayflower Vocabulary</div>
</th>
<th>
<div class='duedate'>Due Oct 15</div>
<div class='title'>Wax Museum</div>
</th>
<th>
<div class='duedate'>Due Oct 15</div>
<div class='title'>American Revolution</div>
</th>
<th>
<div class='duedate'>Due Oct 27</div>
<div class='title'>Jamestown</div>
</th>
<th>
<div class='duedate'>Due Nov 1</div>
<div class='title'>Comparing Colonies</div>
</th>
</tr>
</thead>
<tr>
<td class='student'>
<img class='pic' src='../pics/default.png'>
<span>Jane Doe</span>
</td>
<td><input type='text' value='-'></td>
<td class='late'><input type='text' value='10'></td>
<td><input type='text' value='9.5'></td>
<td><input type='text' value='10'></td>
<td><input type='text' value='5'></td>
</tr>
<tr>
<td class='student'>
<img class='pic' src='../pics/default.png'>
<span>John Doe</span>
</td>
<td><input type='text' value='-'></td>
<td><input type='text' value='8'></td>
<td><input type='text' value='9'></td>
<td><input type='text' value='10'></td>
<td class='late'><input type='text' value='9'></td>
</tr>
</table>
</div>
<div class='controls'>
</div>
Image of issue:

Answer 1

Instead of using border: 1px solid gray you can try this.
td {
text-align: center;
border: 1px solid gray;
border-bottom: 0;
border-right: 0;
background-color: white
}
tr:last-of-type td {
border-bottom: 1px solid gray;
}
td:last-of-type {
border-right: 1px solid gray;
}
/* ------------{GRADEBOOK}------------ */
.gradebook {
position: absolute;
top: 60px;
left: 0;
width: 100vw;
height: calc(100vh - 126px);
overflow-y: scroll;
box-sizing: border-box;
}
/* Table styling*/
table {
table-layout: fixed;
border-collapse: collapse;
}
/* Table heading styling */
thead th {
height: 60px;
width: 100px;
top: 0;
z-index: 2;
position: -webkit-sticky;
position: sticky;
border-right: 1px solid gray;
background-color: white;
}
thead th:first-child {
left: 0;
z-index: 10;
}
th {
padding: 10px 16px;
text-align: left;
font-weight: normal;
color: gray
}
table .duedate {
font-size: 14px;
margin-bottom: 8px
}
table .title {
font-size: 18px;
color: #5B7042
}
/* Table data styling */
td {
text-align: center;
border: 1px solid gray;
border-bottom: 0;
border-right: 0;
background-color: white
}
tr:last-of-type td {
border-bottom: 1px solid gray;
}
td:last-of-type {
border-right: 1px solid gray;
}
td.late {
background-color: #EA5D6B
}
td input {
text-align: center;
padding: 4px;
margin: 0;
width: 114px;
border: none;
}
/* Student Name styling */
.student {
padding: 6px;
box-sizing: border-box;
display: flex;
align-items: center;
margin-bottom: -1px;
}
.pic {
display: inline-block;
width: 25px;
clip-path: circle();
margin-right: 10px;
}
.pic img {
display: none
}
/* ------------{CONTROLS}------------ */
.controls {
display: flex;
position: absolute;
bottom: 10px;
left: 0;
width: 100vw;
height: 56px;
border-top: 1px solid #DDDDDD
}
<link rel="stylesheet" href="../style.css">
<div class='gradebook'>
<table>
<thead>
<tr>
<th style='width: 200px'></th>
<th>
<div class='duedate'>Due Oct 08</div>
<div class='title'>Mayflower Vocabulary</div>
</th>
<th>
<div class='duedate'>Due Oct 15</div>
<div class='title'>Wax Museum</div>
</th>
<th>
<div class='duedate'>Due Oct 15</div>
<div class='title'>American Revolution</div>
</th>
<th>
<div class='duedate'>Due Oct 27</div>
<div class='title'>Jamestown</div>
</th>
<th>
<div class='duedate'>Due Nov 1</div>
<div class='title'>Comparing Colonies</div>
</th>
</tr>
</thead>
<tr>
<td class='student'>
<img class='pic' src='../pics/default.png'>
<span>Jane Doe</span>
</td>
<td><input type='text' value='-'></td>
<td class='late'><input type='text' value='10'></td>
<td><input type='text' value='9.5'></td>
<td><input type='text' value='10'></td>
<td><input type='text' value='5'></td>
</tr>
<tr>
<td class='student'>
<img class='pic' src='../pics/default.png'>
<span>John Doe</span>
</td>
<td><input type='text' value='-'></td>
<td><input type='text' value='8'></td>
<td><input type='text' value='9'></td>
<td><input type='text' value='10'></td>
<td class='late'><input type='text' value='9'></td>
</tr>
</table>
</div>
<div class='controls'>
</div>

Answer 2

My assumption is that problem arises from clashing between two layout alghorithms, table and flex one. Td belongs to table one and putting flex there just make problems.
So only solution is to wrap td content with div, and put flex onto that div.
table{
border-collapse: collapse;
}
td{
border: 1px solid;
}
.flex{
display: flex;
}
<!DOCTYPE html>
<html lang="en">
<body>
<table>
<th>flex</th>
<th>flex</th>
<tr>
<td class='flex'>...</td>
<td>...</td>
</tr>
<tr>
<td>...</td>
<td class='flex'>...</td>
</tr>
</table>
<table>
<th>div flex</th>
<th>div flex</th>
<tr>
<td> <div class='flex'>...</div></td>
<td> <div class='flex'>...</div></td>
</tr>
<tr>
<td> <div class='flex'>...</div></td>
<td> <div class='flex'>...</div></td>
</tr>
</table>
</body>
</html>