Хочу сделать border-radius к элементу

nav {
  margin: 0;
  padding: 0;
}


nav > ul {
  list-style: none;
  border: 1px solid #855a21;
  display: flex;
  align-items: stretch;
  margin-top: 5px;
}

nav > ul li {
  display: flex;
  width: 100%;
  position: relative;
}
  
nav > ul li a {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-grow: 1;
  background: rgb(229,187,129); /* Old browsers */
  background: -moz-linear-gradient(top,  rgba(229,187,129,1) 0%, rgba(124,76,13,1) 70%, rgba(158,100,32,1) 100%); /* FF3.6-15 */
  background: -webkit-linear-gradient(top,  rgba(229,187,129,1) 0%,rgba(124,76,13,1) 70%,rgba(158,100,32,1) 100%); /* Chrome10-25,Safari5.1-6 */
  background: linear-gradient(to bottom,  rgba(229,187,129,1) 0%,rgba(124,76,13,1) 70%,rgba(158,100,32,1) 100%); /* W3C, IE10+, FF16+, Chrome26+, Opera12+, Safari7+ */
  filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#e5bb81', endColorstr='#9e6420',GradientType=0 ); /* IE6-9 */
  font-size: 11px;
  font-weight: 700;
  padding: 7px 15px 7px;
  color: #fff;
  text-decoration: none;
  text-align: center;
  border: 1px solid #f4e2c8;
  outline: 1px solid #855a21;
  font-family: Verdana, Geneva, Tahoma, sans-serif;
  border-radius: 6px;
}

  
nav ul li a:hover {
    color: #4e2c1e;
    background: rgb(255,249,224);
    background: -moz-linear-gradient(top,  rgba(255,249,224,1) 0%, rgba(237,206,140,1) 39%, rgba(237,206,140,1) 79%, rgba(237,206,140,1) 79%, rgba(255,249,224,1) 100%); /* FF3.6-15 */
    background: -webkit-linear-gradient(top,  rgba(255,249,224,1) 0%,rgba(237,206,140,1) 39%,rgba(237,206,140,1) 79%,rgba(237,206,140,1) 79%,rgba(255,249,224,1) 100%); /* Chrome10-25,Safari5.1-6 */
    background: linear-gradient(to bottom,  rgba(255,249,224,1) 0%,rgba(237,206,140,1) 39%,rgba(237,206,140,1) 79%,rgba(237,206,140,1) 79%,rgba(255,249,224,1) 100%); /* W3C, IE10+, FF16+, Chrome26+, Opera12+, Safari7+ */
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#fff9e0', endColorstr='#fff9e0',GradientType=0 ); /* IE6-9 */
  }

 .submenu {
     display: none;
     position: absolute;
     left: 0px;
     top: 100%;
     padding: 0;
     border: none;
 }

 .submenu > li {
     width: 190px;
 }

 nav ul li:hover .submenu  {
    display: block;  
    border: 1px solid #bfa485;  
}

nav ul li:hover .submenu li a {
    border: none ;
    outline: none;
    background: #fcebc6;
    color: #4e2c1e;
    justify-content: flex-start;
}

nav ul li:hover .submenu li a:hover {
    background: #d8af75;
}

.topmenu .prices {
    
    border-right: none;
}

.topmenu .apllication {
    border-left: none;
    outline: none;
    padding-left: 250px;
    padding-right: 30px;
}

<nav>
    <ul class="topmenu">
        <li><a href="#">ГЛАВНАЯ</a></li>
        <li><a href="#">ПОДОБРАТЬ ПЕРСОНАЛ</a>
            <ul class="submenu">
                <li><a href="#">О НАС</a></li>
                <li><a href="#">ЗАДАТЬ ВОПРОС</a></li>
                <li><a href="#">ЭТО ИНТЕРЕСНО</a></li>
                <li><a href="#">ОТЗЫВЫ</a></li>
            </ul>
        </li>
        <li><a href="#" class="prices">ЦЕНЫ</a>
        </li>

        <li><a href="#" class="apllication">ОСТАВИТЬ ЗАЯВКУ</a></li>
        <li><a href="#">ОСТАВИТЬ ВАКАНСИЮ</a></li>
        <li><a href="#">КОНТАКТЫ</a></li>

    </ul>
</nav>