Рамка при наведении

/* Header 
================*/

.header {
  padding: 58px;
  background: #000;
}

.header__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}


/* Nav 
================*/

.nav {
  display: flex;
  gap: 40px;
  font-size: 16px;
  font-weight: 400;
  text-transform: uppercase;
}

.nav__link {
  color: #fff;
  text-decoration: none;
  transition: .1s linear;
}

.nav__link:hover {
  border: 0;
  border-radius: 5px;
  padding: 5px 10px;
  background-color: #643A79;
}

<header class="header">
  <div class="container">
    <div class="header__inner">
      <div class="logo">
        <img src="assets/cuda_logo.png" alt="Cuda">
      </div>
      <nav class="nav">
        <a class="nav__link" href="#">Home</a>
        <a class="nav__link" href="#">About</a>
        <a class="nav__link" href="#">Work</a>
        <a class="nav__link" href="#">Blog</a>
        <a class="nav__link" href="#">Contact</a>
      </nav>
    </div>
  </div>
</header>