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

body{
  background: #1b1b1b;
  color: #f6ff00;
  font-family: sans-serif;
  min-height: 100vh;
}

/* ヘッダー */

header{
  text-align: center;
  padding: 20px;
  border-bottom: 1px solid #f6ff00;
  box-shadow: 0 0 15px #f6ff00;
}

h1{
  letter-spacing: 5px;
  font-size: 2rem;
  text-shadow: 0 0 10px #f6ff00;
}

/* ツールバー */

.toolbar{
  display: flex;
  gap: 15px;
  justify-content: center;
  align-items: center;

  padding: 20px;

  background: rgb(246, 255, 0);

  backdrop-filter: blur(10px);

  border-bottom: 1px solid rgb(246, 255, 0);
}

/* ボタン */

button{
  background: rgb(21, 21, 21);
  color: #f6ff00;

  border: 1px solid #f6ff00;

  padding: 10px 18px;

  cursor: pointer;

  transition: 0.3s;
}

button:hover{
  background: #f6ff00;
  color: rgb(21, 21, 21);

  box-shadow: 0 0 15px #f6ff00;
}

/* キャンバス */

#canvas{
  display: block;

  margin: 30px auto;

  background: #ffffff;

  border: 2px solid #f6ff00;

  box-shadow: 0 0 20px rgba(255,140,0,0.5);

  border-radius: 10px;
}