JSFiddle - React, Tailwind, and code Playground

HTML

<div class="small-scroll">
  <table class="compendium-horizontal-scroll-table compendium-no-left-right-padding-table compendium-mobile-table">
    <thead>
      <tr>
        <th rowspan="2">
          <p>Level</p>
        </th>
        <th rowspan="2">
          <p>Proficiency
            <br>Bonus</p>
        </th>
        <th rowspan="2">
          <p>Sorcery
            <br>Points</p>
        </th>
        <th rowspan="2">
          <p>Features</p>
        </th>
        <th rowspan="2">
          <p>Cantrips
            <br>Known</p>
        </th>
        <th rowspan="2">
          <p>Spells
            <br>Known</p>
        </th>
        <th colspan="9">
          <p>—Spell Slots per Spell Level—</p>
        </th>
      </tr>
      <tr>
        <th class="spell-level-column">
          <p>1st</p>
        </th>
        <th class="spell-level-column">
          <p>2nd</p>
        </th>
        <th class="spell-level-column">
          <p>3rd</p>
        </th>
        <th class="spell-level-column">
          <p>4th</p>
        </th>
        <th class="spell-level-column">
          <p>5th</p>
        </th>
        <th class="spell-level-column">
          <p>6th</p>
        </th>
        <th class="spell-level-column">
          <p>7th</p>
        </th>
        <th class="spell-level-column">
          <p>8th</p>
        </th>
        <th class="spell-level-column">
          <p>9th</p>
        </th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td>
          <div class="compendium-mobile-td-label">
            Level
          </div>
          <div class="compendium-mobile-td-value">
            <p>1st</p>
          </div>
        </td>
        <td>
          <div class="compendium-mobile-td-label">
            ProficiencyBonus
          </div>
          <div class="compendium-mobile-td-value">
            <p>+2</p>
          </div>
        </td>
        <td>
          <div class="compendium-mobile-td-label">
            SorceryPoints
         ...

CSS

.small-scroll {
  overflow: auto;
}

@media (max-width: 768px) {
  .small-scroll {
    max-height: 400px;
  }
}

.compendium-mobile-td-label {
  display: none;
}