Yo apliqué este código:
HTML
<!DOCTYPE html>
<html>
<head>
<title>Table de colores Hexadecimal, RGB</title>
<link rel="stylesheet" type="text/css" href="Ejercicio13-tabla.css">
</head>
<body>
<!-- Contenido de la página-->
<table border="1px">
<th>Nombre</th>
<th>Hexadecimal</th>
<th>RGB</th>
</tr>
<tr>
<td id="td1">DimGray</td>
<td id="td1">#696969</td>
<td id="td1">105,105,105</td>
</tr>
<tr>
<td id="td2">IndianRed</td>
<td id="td2">#CD5C5C</td>
<td id="td2">205,92,92</td>
</tr>
<tr>
<td id="td3">FireBrick</td>
<td id="td3">#B22222</td>
<td id="td3">178,34,34</td>
</tr>
<tr>
<td id="td4">DodgerBlue</td>
<td id="td4">#1E90FF</td>
<td id="td4">30,144,255</td>
</tr>
<tr>
<td id="td5">Indigo</td>
<td id="td5">#4B0082</td>
<td id="td5">75,0,130</td>
</tr>
</table>
</body>
</html>
CSS:
/*tabla de colores*/
body {font-family: Arial, sans-serif;}
table {
border: gray 6px solid;}
th{background-color: gray;}
#td1{background-color: #696969; color: white;}
#td2{background-color: #CD5C5C; color: white;}
#td3{background-color: #B22222; color: white;}
#td4{background-color: #1E90FF; color: white;}
#td5{background-color: #4B0082; color: white;}