:root {
  --bg: #e0e5ec;
  --shadow-light: #ffffff;
  --shadow-dark: #a3b1c6;
  --primary: #6c63ff;
}
body {
  background: var(--bg);
  font-family: "Segoe UI", sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}
.game-container {
  background: var(--bg);
  padding: 30px;
  border-radius: 35px;
  box-shadow: inset -6px -6px 10px var(--shadow-light),
    inset 6px 6px 10px var(--shadow-dark);
  display: flex;
  flex-direction: column;
  align-items: center;
}
h1 {
  margin-bottom: 20px;
  color: #444;
  text-shadow: 1px 1px 1px var(--shadow-light);
}
select {
  margin-bottom: 20px;
  padding: 10px;
  border: none;
  border-radius: 20px;
  font-size: 15px;
  background: var(--bg);
  box-shadow: -6px -6px 10px var(--shadow-light),
    6px 6px 10px var(--shadow-dark);
}
.board {
  display: grid;
  grid-template-columns: repeat(3, 100px);
  grid-template-rows: repeat(3, 100px);
  gap: 15px;
}
.cell {
  width: 100px;
  height: 100px;
  font-size: 30px;
  text-align: center;
  line-height: 100px;
  cursor: pointer;
  border-radius: 20px;
  transition: 0.2s;
  user-select: none;
  background: var(--bg);
  box-shadow: inset -6px -6px 10px var(--shadow-light),
    inset 6px 6px 10px var(--shadow-dark);
}
.cell.filled {
  box-shadow: -6px -6px 10px var(--shadow-light),
    6px 6px 10px var(--shadow-dark);
  color: var(--primary);
  pointer-events: none;
}
.status {
  margin: 15px 0;
  font-size: 18px;
  color: #333;
}
button {
  padding: 10px 20px;
  margin-top: 15px;
  border: none;
  border-radius: 20px;
  font-size: 18px;
  background: var(--bg);
  box-shadow: -6px -6px 10px var(--shadow-light),
    6px 6px 10px var(--shadow-dark);
  cursor: pointer;
  transition: 0.2s;
}
button:active {
  box-shadow: inset -4px -4px 8px var(--shadow-light),
    inset 4px 4px 8px var(--shadow-dark);
}
.popup {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.4);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 999;
}
.popup-box {
  background: var(--bg);
  padding: 30px 40px;
  border-radius: 30px;
  box-shadow: -10px -10px 20px var(--shadow-light),
    10px 10px 20px var(--shadow-dark);
  font-size: 23px;
  color: #333;
}