.rail nav {
  display: flex;
  flex: 1;
  flex-direction: column;
  min-height: 0;
}

.nav-group > span {
  display: flex;
  align-items: baseline;
  gap: 6px;
}

.nav-group > span small {
  font-size: 8px;
  font-weight: 500;
  letter-spacing: .04em;
}

.nav-group .nav-btn {
  align-items: flex-start;
}

.nav-btn i {
  flex: 0 0 auto;
  margin-top: 4px;
}

.nav-btn b {
  display: grid;
  gap: 2px;
}

.nav-btn b span {
  line-height: 1.25;
}

.nav-btn b small {
  color: #999;
  font-size: 9px;
  font-weight: 400;
  line-height: 1.2;
}

.nav-btn.active b small {
  color: #777;
}

.nav-group-prototype {
  margin-top: auto;
  padding-top: 14px;
  border-top: 1px solid var(--line);
}

.nav-group-prototype > span {
  color: #aaa;
}

@media (max-width: 1050px) {
  .nav-group > span,
  .nav-btn b {
    display: none;
  }

  .nav-group-prototype {
    padding-top: 8px;
  }
}

@media (max-width: 680px) {
  .rail nav {
    display: flex;
    flex-direction: row;
    width: 100%;
    overflow-x: auto;
  }

  .nav-group {
    display: contents;
  }

  .nav-group-prototype {
    margin: 0;
    padding: 0;
    border: 0;
  }

  .nav-group .nav-btn {
    flex: 0 0 auto;
    min-width: 108px;
    align-items: center;
    justify-content: center;
  }

  .nav-btn b {
    display: block;
  }

  .nav-btn b small {
    display: none;
  }
}