/* 按钮容器，Flex 布局负责居中 */
#scrollTopBtn {
  position: fixed;
  bottom: 30px;
  right: 70px;
  z-index: 1000;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background-color: #ffffff;
  border: none;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  cursor: pointer;
  padding: 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
  display: flex;
  justify-content: center;
  align-items: center;
}
.theme--dark #scrollTopBtn {
  background-color: #2c2c2c;  /* 深色背景 */
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}
#scrollTopBtn.visible {
  opacity: 1 !important;
  visibility: visible !important;
  transform: translateY(0);
}
#scrollTopBtn:hover {
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

/* 
 * 核心修改部分：
 * .arrow-up 容器现在负责绘制顶部的横线
 */
.arrow-up {
  position: relative;
  /* 定义整个图标（横线+箭头）的总尺寸，用于居中 */
  width: 16px;
  height: 24px;
  /* 使用上边框来绘制顶部的横线 */
  border-top: 3px solid #007bff;
  border-radius: 1px; /* 让线条末端稍微圆润 */
}

/* ::before 伪元素绘制箭身 (竖线) */
.arrow-up::before {
  content: '';
  position: absolute;
  /* 定位在容器的下半部分 */
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 3px;
  height: 19px; /* 箭身的高度 */
  background-color: #007bff;
  border-radius: 2px;
}

/* ::after 伪元素绘制箭头 (^) */
.arrow-up::after {
  content: '';
  position: absolute;
  /* 定位在箭身的顶部，形成无缝连接 */
  bottom: 7px; /* 精确调整此值以匹配箭身 */
  left: 50%;
  width: 10px;
  height: 10px;
  border-top: 3px solid #007bff;
  border-right: 3px solid #007bff;
  transform-origin: center center;
  transform: translateX(-50%) rotate(-45deg);
}


/* 进度条样式保持不变 */
.progress-ring {
  position: absolute;
  top: 0;
  left: 0;
}
.progress-ring__circle,
.progress-ring__track {
  transition: stroke-dashoffset 0.1s;
  transform: rotate(-90deg);
  transform-origin: 50% 50%;
}
.progress-ring__track {
  stroke: #e6e6e6;
}
.theme--dark .progress-ring__track {
  stroke: #433f3f;
}
.progress-ring__circle {
  stroke: #007bff;
  stroke-linecap: round;
}

#theme-toggle .theme-icon-sun svg,
#theme-toggle .theme-icon-moon svg {
  transform: translateY(5px);
}
.theme-icon-sun,
.theme-icon-moon {
  display: none;
}
html.theme--light .theme-icon-sun,
body.theme--light .theme-icon-sun {
  display: inline-flex;
}
html.theme--dark .theme-icon-moon,
body.theme--dark .theme-icon-moon {
  display: inline-flex;
}