html, body {
  margin: 0;
  height: 100%;
  overflow: hidden;
}

#app-shell {
  display: grid;
  grid-template-columns: 18% 82%;
  width: 100vw;
  height: 100vh;
  background: #000;
}

#menu-pane,
#main-pane {
  z-index: 1;
  position: relative;
  min-width: 0;
  min-height: 0;
}

#menu-pane {
  border-right: 2px solid #1a1a1a;
  background: #0a0a0a;
  z-index: 9501;
}

#menu-frame,
#main-frame {
  width: 100%;
  height: 100%;
  border: 0;
  display: block;
}

#mobile-menu-btn {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 10000;
  display: none;
  background: rgba(0, 0, 0, 0.8);
  color: #fff;
  border: 2px outset #999;
  padding: 6px 10px;
  font-family: 'Courier New', Courier, monospace;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  cursor: pointer;
}

#mobile-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9000;
  background: rgba(0, 0, 0, 0.45);
}

body.mobile #app-shell {
  display: block;
}

body.mobile #menu-pane {
  display: block;
  position: fixed;
  top: 0;
  left: 0;
  height: 100vh;
  width: min(86vw, 420px);
  z-index: 9501;
  transform: translateX(-100%);
  transition: transform 0.22s ease;
}

body.mobile #main-pane {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  z-index: 1;
}

body.mobile.menu-open #menu-pane {
  transform: translateX(0);
}

body.mobile #mobile-menu-btn {
  display: block;
}

body.mobile.menu-open #mobile-backdrop {
  display: block;
}

@media (max-width: 900px), (pointer: coarse) {
  #app-shell {
    display: block;
  }

  #menu-pane {
    display: block;
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    width: min(86vw, 420px);
    z-index: 9501;
    transform: translateX(-100%);
    transition: transform 0.22s ease;
  }

  #main-pane {
    position: fixed;
    inset: 0;
    width: 100vw;
    height: 100vh;
    z-index: 1;
  }

  #mobile-menu-btn {
    display: block;
  }

  body.menu-open #menu-pane {
    transform: translateX(0);
  }

  body.menu-open #mobile-backdrop {
    display: block;
  }
}