.menu-toggle {
  display: none;
}

@media (max-width: 820px) {
  body.nav-open {
    overflow: hidden;
  }

  .mast {
    padding: 8px 20px;
    background: rgba(3, 3, 3, .96);
    border-bottom: 1px solid rgba(255, 255, 255, .12);
  }

  .mast .brand {
    position: relative;
    z-index: 32;
    width: 158px;
  }

  .menu-toggle {
    position: relative;
    z-index: 32;
    display: grid;
    grid-template-columns: 22px auto;
    grid-template-rows: repeat(3, 3px);
    align-items: center;
    column-gap: 10px;
    width: 88px;
    min-height: 48px;
    padding: 10px 0;
    border: 0;
    background: transparent;
    color: #fff;
    cursor: pointer;
  }

  .menu-toggle span {
    grid-column: 1;
    display: block;
    width: 22px;
    height: 1px;
    background: currentColor;
    transition: transform .25s ease, opacity .2s ease;
  }

  .menu-toggle b {
    grid-column: 2;
    grid-row: 1 / 4;
    font-size: 12px;
    font-weight: 600;
    letter-spacing: .12em;
    text-transform: uppercase;
  }

  .mast .nav {
    position: fixed;
    z-index: 31;
    inset: 72px 0 0;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    padding: 28px 24px max(32px, env(safe-area-inset-bottom));
    background: linear-gradient(160deg, #090909 0%, #170306 100%);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-14px);
    transition: opacity .25s ease, transform .25s ease, visibility 0s linear .25s;
    overflow-y: auto;
  }

  .mast.menu-open .nav {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
    transition-delay: 0s;
  }

  .mast .nav a,
  .mast .nav a:not(.key-btn) {
    display: flex;
    align-items: center;
    min-height: 62px;
    padding: 0 4px;
    border-bottom: 1px solid rgba(255, 255, 255, .13);
    color: #eee;
    font: 400 22px/1.2 Georgia, serif;
    letter-spacing: .02em;
    text-transform: none;
  }

  .mast .nav a::after {
    content: '→';
    margin-left: auto;
    color: #b41523;
    font-family: Arial, sans-serif;
  }

  .mast .nav .key-btn {
    justify-content: center;
    min-height: 56px;
    margin-top: 26px;
    padding: 16px 20px;
    border: 1px solid #b41523;
    background: #9b0d19;
    font: 600 13px/1 Arial, sans-serif;
    letter-spacing: .16em;
    text-transform: uppercase;
  }

  .mast .nav .key-btn::after {
    margin-left: 12px;
    color: #fff;
  }

  .mast.menu-open .menu-toggle span:nth-child(1) {
    transform: translateY(4px) rotate(45deg);
  }

  .mast.menu-open .menu-toggle span:nth-child(2) {
    opacity: 0;
  }

  .mast.menu-open .menu-toggle span:nth-child(3) {
    transform: translateY(-4px) rotate(-45deg);
  }
}