body, html {
  height: 100%;
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  background-size: cover;
}

.bg {
  /* 设定背景图片全屏展示 */
  position: fixed;
  right: 0;
  bottom: 0;
  min-width: 100%; 
  min-height: 100%;
}

.content {
  position: relative;
  z-index: 1;
  text-align: center;
  color: #CFCFCF; 
}

.button, .modal-content button {
  /* 设定按钮的常见样式 */
  padding: 20px;
  margin: 20px;
  font-size: 24px;
  text-align: center;
  cursor: pointer;
  background-color: #333333;
  border: 4px solid #666666;
  color: #00ff00;
  font-family:  Arial, sans-serif;
  transition: background-color 0.3s ease, border-color 0.3s ease;
  text-decoration: none;
  display: block;
  width: 80%;
  margin: 30px auto;
}

.button:hover, .button:active {
  /* 设定按钮点击和悬停时的样式 */
  background-color: #666666;
  border-color: #00ff00;
  color: #ffffff;
}

.copyright {
  /* 版权信息样式设定 */
  position: absolute;
  bottom: 0;
  width: 100%;
  font-size: 14px;
  color: rgba(255, 255, 255, 1);
  text-align: center;
}

.modal {
  /* 模态框样式设定 */
  display: none;
  position: fixed;
  z-index: 1;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0, 0, 0, 0.5);
}

.modal-content {
  /* 模态框内容样式设定 */
  background-color: #ebe7e0;
  margin: 15% auto;
  padding: 20px;
  border: 1px solid #888;
  width: 30%;
  border-radius: 12px;
  border: 3px solid #2f482d;
  font-family: 'Courier New', Courier, monospace; 
  color: #3e4146;
}

.close-button {
  /* 关闭按钮样式设定 */
  color: #2f482d;
  float: right;
  font-size: 28px;
  font-weight: bold;
}

.modal-content h2 {
  /* 模态框标题样式设定 */
  text-align: center;
  color: #5a5c5f;
}

.speed-setting, .bg-music-setting {
  /* 游戏速度设定和背景音乐开关的样式 */
  display: flex;
  justify-content: flex-start;
  align-items: center;
  width: 50%; 
  margin: auto;
}

#speed-input, #bgMusicSwitch {
  /* 输入框的样式 */
  margin-left: 20px;
  width: 50px;
  background: #dfd5b1;
  border: none;
  color: #3e4146;
  padding: 10px;
  font-family: 'Courier New', Courier, monospace; 
  font-size: 1em;  
}

#speed-input::placeholder {
  color: #3e4146;
  opacity: 0.5;
}

.radio-option, .bg-music-setting h2, .speed-setting h2 {
  /* 单选框和标题具有类似的样式 */
  display: flex;
  justify-content: center;
  align-items: center;
  white-space: nowrap;
}