:root {
  --ink: #2b2932;
  --muted: #66606c;
  --paper: rgba(255, 255, 255, 0.94);
  --line: rgba(43, 41, 50, 0.14);
  --board: #81c7c0;
  --rose: #f58bac;
  --amber: #f5c65f;
}

* {
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  color: var(--ink);
  background:
    linear-gradient(rgba(255, 255, 255, 0.72), rgba(255, 255, 255, 0.82)),
    url("../../res/images/lovekanami.jpg") center / cover fixed;
  touch-action: manipulation;
}

button,
a {
  font: inherit;
}

.game-shell {
  width: min(760px, calc(100% - 28px));
  margin: 0 auto;
  padding: 22px 0 34px;
}

.topbar {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 26px;
}

.topbar a {
  color: var(--ink);
  text-decoration: none;
  font-weight: 800;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
}

.eyebrow {
  margin: 0 0 8px;
  color: #2f8178;
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0;
}

h1 {
  margin: 0;
  font-size: 4rem;
  line-height: 1;
}

.hero p:last-child {
  max-width: 650px;
  margin: 14px 0 18px;
  color: var(--muted);
  line-height: 1.7;
}

.panel {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 18px 40px rgba(43, 41, 50, 0.13);
}

.hud {
  display: grid;
  grid-template-columns: 1fr 1fr auto;
  align-items: center;
  gap: 10px;
  padding: 12px;
}

.hud span {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
}

.hud strong {
  display: block;
  margin-top: 2px;
  font-size: 1.35rem;
}

button {
  min-height: 44px;
  border: 0;
  border-radius: 8px;
  padding: 0 18px;
  color: #25212a;
  background: linear-gradient(135deg, var(--amber), var(--rose));
  font-weight: 900;
  cursor: pointer;
}

.board-wrap {
  margin-top: 16px;
  touch-action: none;
}

.board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  width: min(100%, 560px);
  aspect-ratio: 1;
  margin: 0 auto;
  padding: 10px;
  border-radius: 8px;
  background: rgba(129, 199, 192, 0.78);
  border: 1px solid rgba(43, 41, 50, 0.12);
  box-shadow: 0 20px 46px rgba(43, 41, 50, 0.18);
}

.cell {
  display: grid;
  place-items: center;
  min-width: 0;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.42);
  color: #2f2b34;
  font-weight: 900;
  text-align: center;
  line-height: 1.1;
  overflow-wrap: anywhere;
}

.tile {
  padding: 6px;
  box-shadow: inset 0 -8px 18px rgba(43, 41, 50, 0.08);
}

.value-2 { background: #fff4c7; font-size: 1.6rem; }
.value-4 { background: #ffd8a8; font-size: 1.35rem; }
.value-8 { background: #ffb0a6; font-size: 1rem; }
.value-16 { background: #f58bac; color: white; font-size: 0.95rem; }
.value-32 { background: #a3d8f4; font-size: 0.9rem; }
.value-64 { background: #81c7c0; color: white; font-size: 0.9rem; }
.value-128,
.value-256,
.value-512,
.value-1024,
.value-2048 { background: #6f5f90; color: white; font-size: 0.82rem; }

.message {
  margin-top: 16px;
  padding: 14px 16px;
  color: var(--muted);
  line-height: 1.6;
}

@media (max-width: 560px) {
  .board {
    gap: 7px;
    padding: 7px;
  }

  .hud {
    grid-template-columns: repeat(2, 1fr);
  }

  .hud button {
    grid-column: 1 / -1;
  }

  h1 {
    font-size: 2.3rem;
  }
}