Untitled

<!DOCTYPE html>
<html>
  <head>
    <style>
      body, html {
        margin: 0;
        height: 100%;
      }

      .flex-column {
        display: flex;
        flex-direction: column;
      }

      .fill {
        flex: 1 0 100%;
      }

      .no-scroll-y {
        overflow-y: hidden;
      }

      .scroll-y {
        overflow: scroll;
        height: 100%;
        -webkit-overflow-scrolling: touch;
      }

      #map, #list {
        flex: 1 0 50%;
      }

      #map { background: blue; }
      #list { background: green; }

      .list-item {
        border-top: 1px solid black;
        background: darkgreen;
        padding: 30px 0;
        text-align: center;
      }
    </style>
  </head>
  <body class="flex-column">
    <div class="fill no-scroll-y flex-column">
      <div id="map"></div>
      <div id="list" class="no-scroll-y">
        <div class="scroll-y">
          <div class="list-item">1</div>
          <div class="list-item">2</div>
          <div class="list-item">3</div>
          <div class="list-item">4</div>
          <div class="list-item">5</div>
          <div class="list-item">6</div>
          <div class="list-item">7</div>
          <div class="list-item">8</div>
          <div class="list-item">9</div>
          <div class="list-item">10</div>
          <div class="list-item">11</div>
          <div class="list-item">12</div>
          <div class="list-item">13</div>
          <div class="list-item">14</div>
          <div class="list-item">15</div>
          <div class="list-item">16</div>
          <div class="list-item">17</div>
          <div class="list-item">18</div>
          <div class="list-item">19</div>
          <div class="list-item">20</div>
          <div class="list-item">21</div>
          <div class="list-item">22</div>
          <div class="list-item">23</div>
          <div class="list-item">24</div>
          <div class="list-item">25</div>
          <div class="list-item">26</div>
          <div class="list-item">27</div>
          <div class="list-item">28</div>
        </div>
      </div>
    </div>
  </body>
</html>