<nav>
  <a href="#">No mask</a>
  <ul class="list">
    <li><a href="#">About</a></li>
    <li><a href="#">Projects</a></li>
    <li><a href="#">News</a></li>
    <li><a href="#">Contact</a></li>
  </ul>
  <button class="search">Search</button>
  <button class="menu">Menu</button>
</nav>
<nav class="mask">
  <a href="#">Mask with linear-gradient</a>
  <ul class="list">
    <li><a href="#">About</a></li>
    <li><a href="#">Projects</a></li>
    <li><a href="#">News</a></li>
    <li><a href="#">Contact</a></li>
  </ul>
  <button class="search">Search</button>
  <button class="menu">Menu</button>
</nav>
<nav class="mask-pattern">
  <a href="#">Mask with linear-gradient and repeated image</a>
  <ul class="list">
    <li><a href="#">About</a></li>
    <li><a href="#">Projects</a></li>
    <li><a href="#">News</a></li>
    <li><a href="#">Contact</a></li>
  </ul>
  <button class="search">Search</button>
  <button class="menu">Menu</button>
</nav>
<img src="https://images.unsplash.com/photo-1629812456605-4a044aa38fbc?crop=entropy&cs=tinysrgb&fm=jpg&ixid=MnwzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE2NTc3ODI1OTg&ixlib=rb-1.2.1&q=80" alt="">

* {
  box-sizing: border-box;
}
body {
  margin: 0;
  min-height: 200vh;
  font-size: 0;
  font-family: Helvetica, Verdana, sans-serif;
}
nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  padding: 16px 20px 30px 20px;
  display: flex;
  align-items: center;
  transition: 0.3s ease-out;
  backdrop-filter: blur(8px) brightness(1.2);
  -webkit-backdrop-filter: blur(8px) brightness(1.2);
  text-shadow: 0 0 5px rgba(0,0,0,0.5);
  color: white;
  font-size: 16px;
  &.mask {
    top: 150px;
    mask-image: linear-gradient(black 70%, transparent);
    -webkit-mask-image: linear-gradient(black 70%, transparent);
  }
  &.mask-pattern {
    top: 300px;
    mask-image: url("data:image/svg+xml, %3Csvg xmlns=%27http://www.w3.org/2000/svg%27 viewBox=%270 0 12.21 10.57%27%3E%3Cpath fill=%27%23ffffff%27 d=%27M6.1 0h6.11L9.16 5.29 6.1 10.57 3.05 5.29 0 0h6.1z%27/%3E%3C/svg%3E"), linear-gradient(black calc(100% - 30px), transparent calc(100% - 30px));
    mask-size: auto 30px, 100% 100%;
    mask-repeat: repeat-x, no-repeat;
    mask-position: left bottom, top left;
    
    -webkit-mask-image: url("data:image/svg+xml, %3Csvg xmlns=%27http://www.w3.org/2000/svg%27 viewBox=%270 0 12.21 10.57%27%3E%3Cpath fill=%27%23ffffff%27 d=%27M6.1 0h6.11L9.16 5.29 6.1 10.57 3.05 5.29 0 0h6.1z%27/%3E%3C/svg%3E"), linear-gradient(black calc(100% - 30px), transparent calc(100% - 30px));
    -webkit-mask-size: auto 30px, 100% 100%;
    -webkit-mask-repeat: repeat-x, no-repeat;
    -webkit-mask-position: left bottom, top left;
  }

  @media (min-width: 640px) {
    padding: 16px 50px 30px 50px;
  }
}
nav.is-hidden {
  transform: translateY(-100%);
}
a {
  color: inherit;
  text-decoration: none;
  &:hover,
  &:focus {
    text-decoration: underline;
  }
}
.list {
  list-style-type: none;
  margin-left: auto;
  display: none;
  @media (min-width: 640px) {
    display: flex;
  }
  li {
    margin-left: 20px;
  }
}
.search {
  display: inline-block;
  padding: 0;
  font-size: 0;
  background: none;
  border: none;
  margin-left: auto;
  filter: drop-shadow(0 0 5px rgba(0,0,0,.5));
  @media (min-width: 640px) {
    margin-left: 20px;
  }
  
  &::before {
    content: '';
    display: inline-block;
    width: 2rem;
    height: 2rem;
    background: center/1.3rem 1.3rem no-repeat url("data:image/svg+xml, %3Csvg%20xmlns=%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox=%270%200%2015.17%2014.81%27%20width=%2715.17%27%20height=%2714.81%27%3E%3Cpath%20d=%27M6,.67A5.34,5.34,0,1,1,.67,6,5.33,5.33,0,0,1,6,.67ZM9.86,9.58l4.85,4.75Z%27%20fill=%27none%27%20stroke=%27%23fff%27%20stroke-width=%271.33%27%2F%3E%3C%2Fsvg%3E");
  }
}
.menu {
  display: inline-block;
  padding: 0;
  font-size: 0;
  background: none;
  border:  none;
  margin-left: 20px;
  filter: drop-shadow(0 0 5px rgba(0,0,0,.5));
  &::before {
    content: url("data:image/svg+xml, %3Csvg%20xmlns=%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox=%270%200%2024.8%2018.92%27%20width=%2724.8%27%20height=%2718.92%27%3E%3Cpath%20d=%27M23.8,9.46H1m22.8,8.46H1M23.8,1H1%27%20fill=%27none%27%20stroke=%27%23fff%27%20stroke-linecap=%27round%27%20stroke-width=%272%27%2F%3E%3C%2Fsvg%3E")
  }
  @media (min-width: 640px) {
    display: none;
  }
}
img {
  width: 100%;
  min-height: 200vh;
  object-fit: cover;
}