body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
  background-image: url('img/bg_school.jpg');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

header {
  background-color: #333;
  color: #fff;
  text-align: center;
  padding: 10px;
  border-radius: 10px;
}

.container {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex: 1; /* 讓 container 區塊占據整個可用空間 */
  margin-top: 60px; /* 避免內容被 header 覆蓋 */
}

.logo {
  width: 10px; /* 調整圖片大小 */
  height: auto;
}

nav{
  background-color: #ddd; /* 第一個 nav 的背景顏色 */
  box-sizing: border-box;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding: 20px;
  border-radius: 10px;
}

main {
  background-color: #bcbcbc9a;
  border-radius: 10px;
  min-height: 100%;
}

nav a {
  width: 150px;
  height: 40px;
  display: flex;
  justify-content: center;
  align-items: center;
  text-decoration: none;
  color: #000;
  background-color: transparent;
  position: relative;
  cursor: pointer;
  line-height: 40px;
  transition: all 0.3s linear;
  margin: 5px; /* 添加一些間距 */
}

nav a > p {
  position: relative;
  z-index: 1;
}

nav a::before,
nav a::after {
  content: "";
  width: 20px;
  height: 20px;
  display: block;
  box-sizing: border-box;
  position: absolute;
  transition: all 0.3s;
}

nav a::before {
  top: 0;
  left: 0;
  border-top: 1px solid #000;
  border-left: 1px solid #000;
}

nav a::after {
  bottom: 0;
  right: 0;
  border-bottom: 1px solid #000;
  border-right: 1px solid #000;
}

nav a:hover::before,
nav a:hover::after {
  width: 100%;
  height: 100%;
}

footer {
  background-color: #333;
  color: #fff;
  padding: 10px;
  text-align: center;
  width: 100%;
  bottom: 0;
}