/* Reset CSS */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: 'Roboto', sans-serif;
  background-color: #f0f4f8;
  color: #333;
  line-height: 1.6;
  /* Thêm các thuộc tính sau */
  display: flex;
  flex-direction: column; 
  justify-content: center;
  align-items: center;
  min-height: 100vh; /* Đảm bảo body luôn có chiều cao tối thiểu bằng chiều cao viewport */
  background: url(https://dthanh.pages.dev/qh.jpg) no-repeat center center fixed;
    background-size: cover;
    opacity: 0.9;
}



/* Header */
header {
  background-color: #0288d1;
  color: white;
  padding: 20px;
  text-align: center;
}

.container {
  width: 90%;
  margin: 0 auto;
  padding: 20px;
  /* Bỏ thuộc tính  margin-bottom: 20px; */ 
}



/* Heading */
h1 {
  font-size: 2rem;
  text-align: center;
  margin-bottom: 20px;
  color: #fff;
}

/* Danh sách */
.resource-list {
  list-style: none;
  background-color: #ffffff;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  padding: 20px;
}

.resource-list li {
  padding: 10px;
  border-bottom: 1px solid #eee;
}

.resource-list li:last-child {
  border-bottom: none;
}

.resource-list a {
  text-decoration: none;
  color: #0288d1;
  transition: color 0.3s ease;
}

.resource-list a:hover {
  color: #01579b;
}

.resource-list span.toggle {
  cursor: pointer;
  color: #0288d1;
  transition: color 0.3s ease;
  font-weight: bold;
}

.resource-list span.toggle:hover {
  color: #01579b;
}

.resource-list ul {
  padding-left: 20px;
  display: none;
}

.resource-list ul li {
  font-size: 0.9rem;
  color: #555;
}

.resource-list ul li a {
  font-weight: normal;
}

.resource-list ul ul {
  padding-left: 20px;
}

.resource-list ul ul li {
  font-size: 0.8rem;
}

/* Footer */
footer {
  background-color: #0288d1;
  color: white;
  padding: 20px;
  text-align: center;
  /* Bỏ position: fixed; */ 
  /* Bỏ bottom: 0; */
  /* Bỏ width: 100%; */
  /* Thêm thuộc tính sau */
  margin-top: auto; 
}

/* Dropdown */
#giaiDoan {
  text-align: center;
  margin-bottom: 20px;
}

#giaiDoan label {
  margin-right: 10px;
  font-weight: bold;
}

#giaiDoan select {
  padding: 8px;
  border: 1px solid #ccc;
  border-radius: 5px;
}

/* Responsive */
@media screen and (max-width: 768px) {
  .container {
    width: 100%;
    padding: 10px;
  }

  h1 {
    font-size: 1.5rem;
  }

  .resource-list li {
    padding: 8px;
  }
}