Бургер меню. Вариант 1.

HTML

<header>
  <div class="logo">Мой сайт</div>

  <button class="burger" id="openMenu" aria-label="Открыть меню">
    <svg
      xmlns="http://www.w3.org/2000/svg"
      width="28"
      height="28"
      viewBox="0 0 24 24"
      fill="none"
      stroke="currentColor"
      stroke-width="2"
      stroke-linecap="round"
      stroke-linejoin="round"
    >
      <line x1="3" y1="6" x2="21" y2="6"></line>
      <line x1="3" y1="12" x2="21" y2="12"></line>
      <line x1="3" y1="18" x2="21" y2="18"></line>
    </svg>
  </button>

  <button class="close" id="closeMenu" aria-label="Закрыть меню">
    <svg
      xmlns="http://www.w3.org/2000/svg"
      width="28"
      height="28"
      viewBox="0 0 24 24"
      fill="none"
      stroke="currentColor"
      stroke-width="2"
      stroke-linecap="round"
      stroke-linejoin="round"
    >
      <line x1="18" y1="6" x2="6" y2="18"></line>
      <line x1="6" y1="6" x2="18" y2="18"></line>
    </svg>
  </button>

  <nav class="menu" id="menu">
    <a href="#">Главная</a>
    <a href="#">О нас</a>
    <a href="#">Услуги</a>
    <a href="#">Контакты</a>
  </nav>

  <div class="overlay" id="overlay"></div>
</header>

CSS

body {
  margin: 0;
  font-family: Arial, sans-serif;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
  background: #333;
  color: white;
}

.logo {
  font-weight: bold;
}

/* Desktop Menu */
.menu {
  display: flex;
  gap: 20px;
  z-index: 10;
}

.menu a {
  color: white;
  text-decoration: none;
  font-size: 16px;
}

/* ===== BURGER ===== */
.burger {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 5px;
  margin-left: auto;
}

.close {
  display: none;
}

.burger span {
  width: 25px;
  height: 3px;
  background: white;
  border-radius: 2px;
}

/* Overlay */
.overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease;
  z-index: 5;
}

.overlay.active {
  opacity: 1;
  visibility: visible;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  header {
    justify-content: center;
  }

  .burger {
    display: flex;
  }

  .close {
    display: none;
  }

  /* ==== NAV ==== */
  .menu {
    position: fixed;
    top: 0;
    right: -250px;
    height: 100%;
    width: 250px;
    background: white;
    flex-direction: column;
    padding: 60px 20px;
    transition: right 0.3s ease;
  }

  .menu a {
    margin: 15px 0;
    font-size: 18px;
    color: black;
  }

  .menu.active {
    right: 0;
  }

  .menu.active ~ .close {
    display: flex;
  }

  .menu.active ~ .burger {
    display: none;
  }
}

JS

const openBtn = document.getElementById("openMenu");
const closeBtn = document.getElementById("closeMenu");
const menu = document.getElementById("menu");
const overlay = document.getElementById("overlay");

// открыть меню
openBtn.addEventListener("click", () => {
  menu.classList.add("active");
  overlay.classList.add("active");
});

// закрыть меню (крестик)
closeBtn.addEventListener("click", () => {
  menu.classList.remove("active");
  overlay.classList.remove("active");
});

// закрыть меню (клик по overlay)
overlay.addEventListener("click", () => {
  menu.classList.remove("active");
  overlay.classList.remove("active");
});