:root {
  font-family: "Segoe UI", Arial, sans-serif;
  color: #1f2933;
  background-color: #f4f6f8;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.app {
  width: min(90vw, 420px);
  background: #ffffff;
  border-radius: 16px;
  padding: 32px 28px;
  box-shadow: 0 15px 45px rgba(15, 23, 42, 0.15);
  text-align: center;
}

h1 {
  margin-top: 0;
  margin-bottom: 8px;
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  letter-spacing: 1px;
}

.status {
  margin: 0 0 24px;
  font-size: 1rem;
  color: #64748b;
  min-height: 1.5em;
}

.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.cell {
  width: 100px;
  height: 100px;
  font-size: 2.4rem;
  font-weight: bold;
  border-radius: 12px;
  border: 2px solid transparent;
  background-color: #f0f4f8;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.2s ease,
    border-color 0.2s ease;
  user-select: none;
}

.cell:hover {
  background-color: #e3e9f2;
  transform: translateY(-3px);
}

.cell.filled {
  cursor: not-allowed;
  background-color: #e2e8f0;
}

.cell.win {
  background-color: #a7f3d0;
  color: #065f46;
  border-color: #10b981;
}

.actions {
  margin-top: 24px;
}

.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 24px;
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
  transition: transform 0.1s ease, box-shadow 0.2s ease;
}

.btn:hover {
  box-shadow: 0 8px 20px rgba(79, 70, 229, 0.4);
}

.btn:active {
  transform: scale(0.98);
}

@media (max-width: 420px) {
  .cell {
    width: 90px;
    height: 90px;
  }
}