JSFiddle - React, Tailwind, and code Playground

HTML

<table class="tg">
  <tr>
    <th class="tg-amwm" rowspan="3">Ученик</th>
    <th class="tg-amwm" colspan="6">Предмет</th>
  </tr>
  <tr>
    <td class="tg-amwm" colspan="3">Информатика</td>
    <td class="tg-amwm" colspan="3">Математика</td>
  </tr>
  <tr>
    <td class="tg-amwm">I четверть</td>
    <td class="tg-amwm">II четверть</td>
    <td class="tg-amwm">1-е полугодие</td>
    <td class="tg-amwm">I четверть</td>
    <td class="tg-amwm">II четверть</td>
    <td class="tg-amwm">1-е полугодие</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Баутин Дима</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">4</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Голубев Миша</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">3</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">4</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Куликов Иван</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Радугина Анна</td>
    <td class="tg-baqh">4</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
    <td class="tg-baqh">5</td>
  </tr>
</table>

CSS

.tg  {border-collapse:collapse;border-spacing:0;}
.tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;}
.tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;}
.tg .tg-baqh{text-align:center;vertical-align:top}
.tg .tg-amwm{font-weight:bold;text-align:center;}
.tg .tg-yw4l{vertical-align:top}