* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: system-ui, sans-serif;
  background: #333333;
  color: #eee;
}

.layout {
  display: flex;
  flex-direction: column;
  height: 100dvh;
  padding: 0.25rem;
}

.title {
  display: block;
  flex-shrink: 0;
  width: 100%;
  margin-bottom: 0.25rem;
  padding: 0;
  border: none;
  background: none;
  font: inherit;
  font-size: clamp(1rem, 2.5vh, 1.75rem);
  font-weight: 300;
  letter-spacing: 0.05em;
  text-align: center;
  color: inherit;
  cursor: pointer;
}

.title:hover {
  color: #0099cc;
}

.grid-area {
  flex: 1;
  min-height: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.grid {
  display: grid;
  margin: 0 auto;
}

.card {
  position: relative;
  padding: 0;
  border: 1px solid #333;
  border-radius: 4px;
  background: none;
  cursor: pointer;
  overflow: hidden;
  transition: border-color 0.2s;
}

.card:not(.revealed):not(.matched):hover {
  border-color: #6c63ff;
}

.card.matched {
  cursor: default;
}

.card img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.card::after {
  content: '';
  position: absolute;
  inset: 0;
  background: #eeeeee;
  transition: opacity 0.3s;
}

.card.revealed::after,
.card.matched::after {
  opacity: 0;
  pointer-events: none;
}

.pair-slider {
  flex-shrink: 0;
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  padding: 0.25rem 0;
}

.pair-slider__label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #aaa;
}

.pair-slider__value {
  font-size: 1rem;
  font-weight: 600;
  color: #0099cc;
  min-width: 1.25rem;
  text-align: center;
}

.pair-slider input[type="range"] {
  flex: 1;
  max-width: 200px;
  accent-color: #0099cc;
  cursor: pointer;
}

@media (min-width: 601px) {
  .layout {
    padding: 0.5rem 4rem 0.5rem 0.5rem;
  }

  .pair-slider {
    position: fixed;
    right: 0.5rem;
    top: 50%;
    transform: translateY(-50%);
    flex-direction: column;
    gap: 0.5rem;
    padding: 0.5rem;
  }

  .pair-slider__label {
    writing-mode: vertical-rl;
  }

  .pair-slider input[type="range"] {
    writing-mode: vertical-lr;
    direction: rtl;
    flex: none;
    width: 8px;
    height: min(180px, 40vh);
    max-width: none;
  }
}