/* Biến màu */
:root {
  --primary-color: #003366;
  --secondary-color: #FFCC00;
  --text-color: #333;
  --light-text-color: #fff;
  --dark-bg: #1a1a1a;
  --light-bg: #f8f8f8;
}

/* Đặt lại cơ bản */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--light-bg);
}

a {
  text-decoration: none;
  color: var(--primary-color);
}

a:hover {
  color: var(--secondary-color);
}

ul {
  list-style: none;
}

/* Tiêu đề trang */
.site-header {
  background-color: var(--primary-color);
  color: var(--light-text-color);
  padding: 1rem 0;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 20px;
}

.site-header .logo {
  color: var(--secondary-color);
  font-size: 2.2rem;
  font-weight: bold;
  letter-spacing: 1px;
  text-transform: uppercase;
  transition: color 0.3s ease;
}

.site-header .logo:hover {
  color: var(--light-text-color);
}

.main-nav .nav-list {
  display: flex;
  gap: 1.5rem;
}

.main-nav .nav-list a {
  color: var(--light-text-color);
  font-weight: 600;
  font-size: 1rem;
  padding: 0.5rem 0;
  position: relative;
}

.main-nav .nav-list a::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background-color: var(--secondary-color);
  transition: width 0.3s ease;
}

.main-nav .nav-list a:hover::after,
.main-nav .nav-list a.active::after {
  width: 100%;
}

.header-actions {
  display: flex;
  gap: 10px;
}

.btn {
  padding: 0.75rem 1.25rem;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-weight: 600;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.btn-login {
  background-color: transparent;
  color: var(--secondary-color);
  border: 2px solid var(--secondary-color);
}

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

.btn-register {
  background-color: var(--secondary-color);
  color: var(--primary-color);
}

.btn-register:hover {
  background-color: #e6b800; /* Slightly darker secondary */
}

.hamburger-menu {
  display: none; /* Hidden on desktop */
  background: none;
  border: none;
  cursor: pointer;
  padding: 10px;
  position: relative;
  z-index: 1001; /* Ensure it's above other elements */
}

.hamburger-menu .bar {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--light-text-color);
  margin: 5px 0;
  transition: 0.4s;
}

/* Chân trang */
.site-footer {
  background-color: var(--dark-bg);
  color: var(--light-text-color);
  padding: 3rem 0 1rem 0;
  margin-top: 3rem;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  padding: 0 20px 2rem 20px;
  flex-wrap: wrap;
}

.footer-column {
  flex: 1;
  min-width: 250px;
}

.footer-column h3 {
  color: var(--secondary-color);
  margin-bottom: 1.5rem;
  font-size: 1.2rem;
}

.footer-column p,
.footer-column a {
  color: #ccc;
  font-size: 0.95rem;
  margin-bottom: 0.8rem;
}

.footer-column a:hover {
  color: var(--secondary-color);
}

.footer-nav ul li a {
  display: block;
  padding: 0.2rem 0;
}

.footer-bottom {
  text-align: center;
  padding-top: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom .copyright {
  font-size: 0.85rem;
  color: #aaa;
}

/* Responsive Design */
@media (max-width: 1024px) {
  .main-nav .nav-list {
    gap: 1rem;
  }
}

@media (max-width: 768px) {
  .header-container {
    flex-wrap: wrap;
    justify-content: center;
    position: relative;
  }

  .site-header .logo {
    order: 1;
    flex-basis: 100%;
    text-align: center;
    margin-bottom: 1rem;
  }

  .header-actions {
    order: 3;
    flex-basis: 100%;
    justify-content: center;
    margin-top: 1rem;
  }

  .hamburger-menu {
    display: block;
    position: absolute;
    top: 1rem;
    right: 20px;
    order: 2;
  }

  .main-nav {
    display: none; /* Hidden by default on mobile */
    flex-direction: column;
    width: 100%;
    background-color: var(--primary-color);
    position: absolute;
    top: 100%; /* Position below the header */
    left: 0;
    padding: 1rem 0;
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
    z-index: 1000;
  }

  .main-nav.active {
    display: flex;
  }

  .main-nav .nav-list {
    flex-direction: column;
    text-align: center;
  }

  .main-nav .nav-list li {
    margin-bottom: 10px;
  }

  .main-nav .nav-list a {
    padding: 10px 20px;
    display: block;
    font-size: 1.1rem;
  }

  .main-nav .nav-list a::after {
    display: none;
  }

  .footer-container {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .footer-column {
    margin-bottom: 2rem;
    width: 100%;
    min-width: unset;
  }

  .footer-column:last-child {
    margin-bottom: 0;
  }
}