在浏览器中垂直旋转、居中到底对齐的表格标题

thead th {
  vertical-align: bottom;
  text-align:     center;
  width:          0.5em;
  min-width:      0.5em;
  padding:        0;
}
thead th span {
  writing-mode: vertical-lr;
  transform:    rotate(180deg);

  /* slight horizontal offset to suit tastes */
  position:relative; left:-2px;
}

/* need following (or explicit width) or else the */
/* cells in the rows will force wrap every word   */
tbody th { white-space:nowrap }

/*************** unrelated formatting ***************/
table { border-collapse:collapse; margin:1em auto }
thead th { font-size:90% }
thead th span { opacity:0.5 }
th, td { vertical-align:middle; padding:0 0.5em }
th { text-align:right; font-weight:normal }

.yes { color:#090; font-weight:bold }
.maybe { color:#660 }
.no  { color:#600 }

tr > * { border-bottom:1px solid rgba(0,0,0,0.2)}
tr:last-child > * { border-bottom: 0 }

<table><thead><tr>
    <th></th>
    <th class="yes"><span>yes</span></th>
    <th class="maybe"><span>maybe</span></th>
    <th class="no"><span>no</span></th>
    <th><span>who?</span></th>
</tr></thead><tbody><tr>
    <th>Fri, Dec 9, 12pm</th>
    <td class="yes">2</td><td class="maybe">1</td><td class="no">1</td>
    <td><button>≡</button></td>
</tr><tr>
    <th>Wed, Dec 14, 12pm</th>
    <td class="yes">4</td><td class="maybe">0</td><td class="no">0</td>
    <td><button>≡</button></td>
</tr><tr>
    <th>Fri, Dec 16, 12pm</th>
    <td class="yes">0</td><td class="maybe">0</td><td class="no">1</td>
    <td><button>≡</button></td>
</tr></tbody></table>