JSFiddle - React, Tailwind, and code Playground
by Simon Hi
HTML
<h1>
table ore (no border-collapse + border 25px everywhere)
</h1><table class="ore">
<thead><tr><th colspan="2">Un petit tableau<th></tr></thead>
<tr><td>Cellule 2.1</td><td>Cellule 2.2</td><tr>
<tr><td>Cellule 3.1</td><td>Cellule 3.2</td><tr>
</table>
<h1>
table ore2 (border-collapse + border 25px everywhere)
</h1>
<table class="ore2">
<thead><tr><th colspan="2">Un petit tableau<th></tr></thead>
<tr><td>Cellule 2.1</td><td>Cellule 2.2</td><tr>
<tr><td>Cellule 3.1</td><td>Cellule 3.2</td><tr>
</table><h1>
table ore3 (border-collapse + border 25px everywhere excepted 1st line with border 0)
</h1>
<table class="ore3">
<thead><tr><th colspan="2">Un petit tableau<th></tr></thead>
<tr><td>Cellule 2.1</td><td>Cellule 2.2</td><tr>
<tr><td>Cellule 3.1</td><td>Cellule 3.2</td><tr>
</table><h1>
table ore4 (border-collapse + border 25px everywhere excepted 1st line with border 100px)
</h1>
<table class="ore4">
<thead><tr><th colspan="2">Un petit tableau<th></tr></thead>
<tr><td>Cellule 2.1</td><td>Cellule 2.2</td><tr>
<tr><td>Cellule 3.1</td><td>Cellule 3.2</td><tr>
</table><h1>
table ore5 (border-collapse + various borders)
</h1>
<table class="ore5">
<thead><tr><th colspan="2">Un petit tableau<th></tr></thead>
<tr><td>Cellule 2.1</td><td>Cellule 2.2</td><tr>
<tr class="green"><td>Cellule 3.1</td><td>Cellule 3.2</td><tr>
</table>CSS
table.ore td {border-bottom: 3px solid blue;}
table.ore tr {border-left: 25px solid red;}
table.ore2 {border-collapse: collapse;}
table.ore2 td {border-bottom: 3px solid blue;}
table.ore2 tr {border-left: 25px solid red;}
table.ore3 {border-collapse: collapse;}
table.ore3 td {border-bottom: 3px solid blue;}
table.ore3 tr {border-left: 25px solid red;}
table.ore3 thead tr {border-left-width: 0;}
table.ore4 {border-collapse: collapse;}
table.ore4 td {border-bottom: 3px solid blue;}
table.ore4 tr {border-left: 25px solid red;}
table.ore4 thead tr {border-left-width: 100px;}
table.ore5 {border-collapse: collapse;}
table.ore5 td {border-bottom: 3px solid blue;}
table.ore5 tr {border-left: 25px solid red;}
table.ore5 thead tr {border-left-width: 100px;}
table.ore5 tr.green {border-left: 200px solid green;}