* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  display: flex;
  flex-direction: column;
  align-items: center;
  background-color: #181818;
}
#board {
  position: relative;
  margin-top: 1rem;
  /* 4/5 Grid */
  width: 360px;
  height: 450px;
  background: #181818;
  touch-action: none;
  border-radius: 8px;
  box-shadow: 0 0 20px rgba(0, 0, 0, 0.342);
}

/* #navigation {
  max-width: 360px;
  color: #ccc;
  padding: 1rem;
  background-color: #181818;
} */

#board div {
  outline: 1px solid #181818;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.15);
}
#board > div:active {
  cursor: grabbing;
}
#goal {
  position: absolute;
  border-radius: 12px;
  background: rgba(100, 255, 100, 0.1) !important;
  border: 2px dashed rgba(100, 255, 100, 0.25);
  pointer-events: none;
  z-index: 0;
  box-shadow: inset 0 0 40px rgba(100, 255, 100, 0.04);
}

#navigation {
  max-width: 360px;
  width: 100%;
  padding: 1rem 0;
  background-color: #181818;
  display: flex;
  justify-content: center;
}

#navigation > div {
  display: flex;
  gap: 0.75rem;
}

.btn {
  appearance: none;
  border: none;
  outline: none;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  padding: 0.65rem 1.4rem;
  border-radius: 8px;
  cursor: pointer;
  color: #eee;
  background: #2a2a2a;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.08),
    0 2px 6px rgba(0, 0, 0, 0.3);
  transition:
    background 0.15s ease,
    transform 0.1s ease;
}

.btn:hover {
  background: #333;
}

.btn:active {
  background: #222;
  transform: scale(0.96);
}

#revert {
  background: #2a3a4a;
}

#revert:hover {
  background: #34495e;
}

#restart {
  background: #4a2a2a;
}

#restart:hover {
  background: #5e3434;
}

.nav-continer {
  width: 100%;
  display: flex;
  justify-content: space-between;
}