* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', sans-serif;
  }
  
  body {
    background-color: #1a2a33;
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
  }
  
  .container {
    width: 360px;
  }
  
  .screen {
    display: none;
    text-align: center;
    padding: 1rem;
  }
  
  .screen.active {
    display: block;
  }
  
  .glow-title {
    font-size: 2rem;
    margin-bottom: 1rem;
    text-align: center;
    color: #31c4be;
    text-shadow: 0 0 5px #31c4be, 0 0 15px #31c4be;
  }
  
  .logo {
    font-size: 2rem;
    color: #31c4be;
    margin-bottom: 1rem;
  }
  
  h2 {
    font-weight: 500;
    margin-bottom: 1rem;
  }
  
  .mark-selector {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1rem;
  }
  
  .mark {
    background-color: #1f3641;
    color: white;
    padding: 0.5rem 1rem;
    font-size: 1.5rem;
    border: none;
    cursor: pointer;
    border-radius: 8px;
    transition: background-color 0.3s;
  }
  
  .mark.active {
    background-color: #a8bfc9;
    color: #1a2a33;
  }
  
  .note {
    font-size: 0.8rem;
    color: #a8bfc9;
    margin-bottom: 1rem;
  }
  
  .btn {
    padding: 0.7rem;
    width: 100%;
    font-size: 1rem;
    border-radius: 8px;
    margin-top: 0.5rem;
    font-weight: bold;
    border: none;
    cursor: pointer;
  }
  
  .yellow {
    background-color: #f2b137;
    color: #1a2a33;
  }
  
  .green {
    background-color: #31c4be;
    color: #1a2a33;
  }
  
  .gray {
    background-color: #a8bfc9;
    color: #1a2a33;
  }
  
  .top-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
  }
  
  #turn-indicator {
    background-color: #1f3641;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-weight: bold;
  }
  
  .reset {
    background: #a8bfc9;
    border: none;
    padding: 0.5rem;
    border-radius: 8px;
    cursor: pointer;
    margin-left: 0.5rem;
  }
  
  .board {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.5rem;
    margin-bottom: 1rem;
  }
  
  .cell {
    width: 100px;
    height: 100px;
    background-color: #1f3641;
    border-radius: 8px;
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
  }
  
  .scoreboard {
    display: flex;
    justify-content: space-between;
    text-align: center;
  }
  
  .score {
    background-color: #1f3641;
    padding: 0.5rem;
    border-radius: 8px;
    flex: 1;
    margin: 0 0.2rem;
  }
  
  .btn-group {
    display: flex;
    justify-content: space-between;
    margin-top: 1rem;
  }