diff --git a/chapter04/chapter04-project01.html b/chapter04/chapter04-project01.html
index 3e7f4acce2c6861610c5453744812158059f9cab..d89b52a314b49701530e443beb61ba0388684459 100644
--- a/chapter04/chapter04-project01.html
+++ b/chapter04/chapter04-project01.html
@@ -12,58 +12,60 @@
         
         <thead>
             <tr>
-                <th>S</th>
-                <th>M</th>
-                <th>T</th>
-                <th>W</th>
-                <th>T</th>
-                <th>F</th>
-                <th>S</th>
+                <th scope="col">S</th>
+                <th scope="col">M</th>
+                <th scope="col">T</th>
+                <th scope="col">W</th>
+                <th scope="col">T</th>
+                <th scope="col">F</th>
+                <th scope="col">S</th>
             </tr>
         </thead>
-        <tr>
-            <td colspan="3"></td>
-            <td>1</td>
-            <td>2</td>
-            <td>3</td>
-            <td>4</td>
-        </tr>
-        <tr>
-            <td>5</td>
-            <td>6</td>
-            <td>7</td>
-            <td>8</td>
-            <td>9</td>
-            <td>10</td>
-            <td>11</td>
-        </tr>
-        <tr>
-            <td>12</td>
-            <td>13</td>
-            <td>14</td>
-            <td>15</td>
-            <td>16</td>
-            <td>17</td>
-            <td>18</td>
-        </tr>
-        <tr>
-            <td>19</td>
-            <td>20</td>
-            <td>21</td>
-            <td>22</td>
-            <td>23</td>
-            <td>24</td>
-            <td>25</td>
-        </tr>
-        <tr>
-            <td>26</td>
-            <td>27</td>
-            <td>28</td>
-            <td>29</td>
-            <td>30</td>
-            <td>31</td>
-            <td></td>
-        </tr>
+        <tbody>
+            <tr>
+                <td colspan="3"></td>
+                <td>1</td>
+                <td>2</td>
+                <td>3</td>
+                <td>4</td>
+            </tr>
+            <tr>
+                <td>5</td>
+                <td>6</td>
+                <td>7</td>
+                <td>8</td>
+                <td>9</td>
+                <td>10</td>
+                <td>11</td>
+            </tr>
+            <tr>
+                <td>12</td>
+                <td>13</td>
+                <td>14</td>
+                <td>15</td>
+                <td>16</td>
+                <td>17</td>
+                <td>18</td>
+            </tr>
+            <tr>
+                <td>19</td>
+                <td>20</td>
+                <td>21</td>
+                <td>22</td>
+                <td>23</td>
+                <td>24</td>
+                <td>25</td>
+            </tr>
+            <tr>
+                <td>26</td>
+                <td>27</td>
+                <td>28</td>
+                <td>29</td>
+                <td>30</td>
+                <td>31</td>
+                <td></td>
+            </tr>
+        <tbody>
         <tfoot>
             <tr>
                 <td class="month-prev" colspan="3">&#171; Sep</td>