header {
  padding-block: 1.25rem;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;

  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background .3s ease, backdrop-filter .3s ease, box-shadow .3s ease, border-color .3s ease;

  & nav {
    display: flex;
    align-items: center;
    gap: 2rem;
  }

  & .logo {
    margin-right: auto;

    & img {
      width: 7rem;
    }
  }

  & .menu {
    display: flex;
    align-items: center;
    gap: 2rem;

    & a:not(.btn) {
      color: rgb(202, 202, 202);
      transition: color .5s ease;
      position: relative;

      &::after {
        content: "";
        position: absolute;
        bottom: -4px; left:0; right: 0;
        height: 2px;
        background-color: var(--orange);
        transform: scaleX(0);
        transition: transform .3s ease;
      }

      &:hover {
        color: white;
      }

      &:hover::after {
        transform: scaleX(1);
      }

      /* página atual */
      &[aria-current="page"] {
        color: var(--white);

        &::after {
          transform: scaleX(1);
        }
      }
    }
  }
}

header.scrolled,
header.menu-open {
  background: rgba(6, 18, 48, 0.72);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, .16);
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}

/* botão hambúrguer: 3 linhas feitas com o span e seus pseudo-elementos */
.menu-toggle {
  display: none;
  width: 2.75rem;
  height: 2.75rem;
  background: none;
  border: 0;
  cursor: pointer;
  position: relative;

  & span,
  & span::before,
  & span::after {
    position: absolute;
    left: 50%;
    width: 1.5rem;
    height: 2px;
    margin-left: -0.75rem;
    background: var(--white);
    border-radius: 2px;
    transition: transform .3s ease, opacity .3s ease;
  }

  & span { top: 50%; }

  & span::before,
  & span::after {
    content: "";
    left: 0;
    margin-left: 0;
  }

  & span::before { transform: translateY(-7px); }
  & span::after  { transform: translateY(7px); }

  &[aria-expanded="true"] span { background: transparent; }
  &[aria-expanded="true"] span::before { transform: rotate(45deg); background: var(--white); }
  &[aria-expanded="true"] span::after  { transform: rotate(-45deg); background: var(--white); }
}

@media (width < 62.5rem) {
  header.menu-open {
    background: var(--navy-dk);
  }

  .menu-toggle {
    display: block;
  }

  header .menu {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0.5rem 2rem 2rem;
    background: var(--navy-dk);
    border-bottom: 1px solid rgba(255, 255, 255, .08);

    visibility: hidden;
    opacity: 0;
    transform: translateY(-0.5rem);
    transition: opacity .25s ease, transform .25s ease, visibility .25s;

    & a:not(.btn) {
      padding-block: 1rem;
      font-size: 1.1rem;
      border-bottom: 1px solid rgba(255, 255, 255, .08);

      &::after { display: none; }
    }

    & .btn {
      margin-top: 1.5rem;
      justify-content: center;
    }
  }

  header.menu-open .menu {
    visibility: visible;
    opacity: 1;
    transform: none;
  }
}