/* Thiết lập chung */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

:root {
  --primary-color: #2c3e50; /* Màu xám đậm */
  --accent-color: #3498db; /* Màu xanh dương */
  --bg-color: #f4f7f6;
  --text-color: #333;
  --white: #ffffff;
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
}

/* Header */
.main-header {
  background-color: var(--primary-color);
  color: var(--white);
  padding: 2rem 1rem;
  text-align: center;
  border-bottom: 4px solid var(--accent-color);
}

/* Layout Container */
.container {
  display: flex;
  max-width: 1200px;
  margin: 2rem auto;
  gap: 2rem;
  padding: 0 1rem;
}

/* Sidebar (Profile + Nav) */
.sidebar {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.profile-card {
  padding: 1.5rem;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  text-align: center;
  background: linear-gradient(rgba(56, 68, 64, 0.7), rgba(4, 9, 30, 0.7));
}

.avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--accent-color);
  margin-bottom: 1rem;
}

.profile-info h2 {
  color: lightblue;
  margin-bottom: 0.5rem;
}
.tr {
  color: lightblue;
}
.bio {
  font-size: 0.9rem;
  margin-top: 1rem;
  color: lightgrey;
  font-style: italic;
}

.nav-menu {
  background: var(--white);
  padding: 1.5rem;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.nav-menu h3 {
  border-bottom: 2px solid var(--bg-color);
  padding-bottom: 0.5rem;
  margin-bottom: 1rem;
}

.nav-menu ul {
  list-style: none;
}

.nav-menu ul li a {
  text-decoration: none;
  color: var(--text-color);
  display: block;
  padding: 0.7rem;
  border-radius: 5px;
  transition: all 0.3s ease;
}

.nav-menu ul li a:hover {
  background-color: lightblue;
  color: var(--white);
  padding-left: 1.5rem;
}

/* Main Content Area */
.content {
  flex: 2;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.assignment-card {
  background: var(--white);
  padding: 1.5rem;
  border-radius: 10px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: transform 0.2s;
}

.assignment-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.card-info h3 {
  color: var(--accent-color);
  margin-bottom: 0.5rem;
}

/* Button */
.btn-detail {
  text-decoration: none;
  background-color: var(--accent-color);
  color: var(--white);
  padding: 0.6rem 1.2rem;
  border-radius: 5px;
  font-weight: bold;
  transition: background 0.3s;
  white-space: nowrap;
}

.btn-detail:hover {
  background-color: var(--primary-color);
}

/* Footer */
.main-footer {
  text-align: center;
  padding: 2rem;
  background: var(--primary-color);
  color: var(--white);
  margin-top: 3rem;
}

/* Responsive cho điện thoại */
@media (max-width: 768px) {
  .container {
    flex-direction: column;
  }

  .assignment-card {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }

  .btn-detail {
    width: 100%;
    text-align: center;
  }
}

.header {
  min-height: 100vh;
  width: 100%;
  background-image:
    linear-gradient(rgba(4, 9, 30, 0.7), rgba(4, 9, 30, 0.7)),
    url(./img/background/meobay.jpg);
  background-position: center;
  background-size: cover;
  position: relative;
}

.main-footer {
  background-image: linear-gradient(rgba(4, 9, 30, 0.7), rgba(4, 9, 30, 0.7));
  background-position: center;
  background-size: cover;
  position: relative;
}