Position:sticky doesn't work if you have position:fixed ?

position:fixed

position:sticky

  <nav class="nav">
           <div class="title">
               <h4><a href="#">Map</a></h4>
           </div>
            <ul class="nav-links">
               <li>
                   <a href="#"> HOME</a>
               </li>
               <li>
                   <a href="#">ABOUT
                   </a>
               </li>
               <li>
                   <a href=""> MAP</a>
               </li>
               <li>
                   <a href="#">Chronology</a>
               </li>
               <li>
                   <a href="#">CONTACT</a>
               </li>
            </ul>
            <div class="humberger">
               <div class="line line1"></div>
               <div class="line line2"></div>
               <div class="line line3"></div>
           </div>
            
        </nav>
       </div>
    <div class="chronology-title">
        <h1 class="capital">Chronology</h1>
    </div>
    <div class="chronology-table">
        <table>
            <tr>
                <th>date</th>	<th>location</th>	<th>victim</th> <th>cause of death</th><th>info</th>
            </tr>
                
<tr>	<td>a</td>	<td>b</td>	<td>c</td>	<td>d</td>	<td></td>	</tr>

What I have tried:

CSS for nav bar:
<pre lang="CSS">.nav {
    /* padding: 20px; */
    display:flex;
    justify-content: space-between;
    align-items: center;
    background-color: rgba(212, 190, 188);
    min-height: 10vh;
    position: fixed;
    width:100%;
    
    /* right:0;
    left: 0; */
  
    z-index:200;
    padding:0 30px;

}

.humberger {
    position:relative;
    width: 50px;
    height: 40px;
  
    display:none;
    padding-left:30px;
    top:10px;
 
}

.humberger div {
    width: 25px;
    height: 2px;
    margin: 5px auto;
    background-color: #000000;
    

 }

.nav-links {
    display: flex;
    justify-content:space-around;
    align-items: center;
    /* position:relative; */
    /* right:15%; */
    width: 70%;

}

.nav-links li {
    list-style: none;
    margin-right: 30px;
    padding: 20px 0px;
    font-size: 26px;
    font-weight: 600;
    white-space: nowrap;
    /* font-family: 'Merienda', cursive; */
    text-transform: uppercase;
    text-align:center;
    
    
}

.nav-links li a {
    text-decoration: none;
    color: #000000;
    position: relative;
    transition: color 0.2s ease;

}

.nav-links li a::after {
   content:'';
   position: absolute;
   background-color: #fff;
   height: 3px;
   width: 0;
   left: 0;
   bottom: -5px; 
   transition: all 0.4s ease;
}

.nav-links li a:hover {
    color: #fff;
}
.nav-links li a:hover::after {
    width: 100%;
}

.chronology-table {
    margin: 20px 100px 40px 100px;
}

table {
    border-collapse: collapse;

}


th {
position:sticky;
/* position: -webkit-sticky; */
 top:-1px;
 padding:10px;
 font-size:20px;
 border:1px solid black;
 background-color:rgba(220, 224, 193);
 text-transform: capitalize;
}


 th::before {
    content:'';
    position:absolute;
    top: 0;
    left: 0;
    width:100%;
    height: 100%;
}

 table td {
    padding: 5px 10px;
    border: solid 1px black;
}