css – 如何绘制具有不同边框宽度的偶数表边框？

table#crossword tr:first-child td {
  border-top: 1px solid black;
}
table#crossword tr:last-child td {
  border-bottom: 1px solid black;
}
table#crossword tr td:first-child {
  border-left: 1px solid black;
}
table#crossword tr td:last-child {
  border-right: 1px solid black;
}

它看起来有点低,但除此之外没有其他选项可以使最外边框均匀对齐

演示

#crossword {
   border-spacing: 0px;
   border-collapse:collapse;
}

.word {
  vertical-align: middle;
  align-items: center;
  text-align: center;
  justify-content: center;
  margin: 0;
  padding: 0;
}

.cell {
  width: 30px;
  height: 30px;
  margin: 0;
  padding: 0;
}

.letter {
  border: 1px solid black;
}

.keyword {
  border-width: 2px;
  BACkground-color: gray;
}

table#crossword tr:first-child td {
  border-top: 1px solid black;
}
table#crossword tr:last-child td {
  border-bottom: 1px solid black;
}
table#crossword tr td:first-child {
  border-left: 1px solid black;
}

<table id="crossword">
    <tr class="word">
        <td class="cell letter">W</td>
        <td class="cell letter keyword">C</td>
        <td class="cell letter">A</td>
    </tr>
    <tr class="word">
        <td class="cell letter">W</td>
        <td class="cell letter keyword">C</td>
        <td class="cell letter">A</td>
    </tr>
    <tr class="word">
        <td class="cell letter">W</td>
        <td class="cell letter keyword">C</td>
        <td class="cell letter">A</td>
    </tr>
</table>