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

#start-panel {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2.5vh;
  padding: 8vh 10vh;
  background: rgba(0, 0, 0, 0.55);
  border: 2px solid #ffffff;
  border-radius: 12px;
  color: #ffffff;
  font-family: 'MS ゴシック', sans-serif;
}

#start-panel h1 {
  margin: 0;
  font-size: 7vh;
  letter-spacing: 0.2em;
}

#start-form {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2.5vh;
}

#start-form label {
  font-size: 3vh;
}

#start-form input[type="text"] {
  width: 45vh;
  padding: 1.5vh;
  font-size: 2.5vh;
  text-align: center;
  border: 2px solid #ffffff;
  border-radius: 6px;
  background: #1a1a2e;
  color: #ffffff;
  box-sizing: border-box;
}

#start-form input[type="text"]:focus {
  outline: 2px solid #1e90ff;
}

#start-form button {
  width: 40vh;
  padding: 2.5vh;
  font-size: 3vh;
  font-family: inherit;
  font-weight: bold;
  letter-spacing: 0.1em;
  color: #12121a;
  background: #f2b907;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

#start-form button:hover {
  background: #ffd23f;
}

#start-form button:active {
  transform: translateY(1px);
}