/* Biến màu */
:root {
  --primary-color: #2A2E43;
  --accent-color: #FFD700;
  --text-color: #f0f0f0;
  --dark-text-color: #333;
  --light-bg-color: #f8f8f8;
}

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

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

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

/* ==================== Header ==================== */
.site-header {
  background-color: var(--primary-color);
  color: var(--text-color);
  padding: 1rem 2rem;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
  position: sticky;
  top: 0;
  z-index: 1000;
}

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

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

.logo:hover {
  color: #fff;
}

.main-nav ul {
  display: flex;
  gap: 1.8rem;
}

.main-nav a {
  color: var(--text-color);
  font-size: 1rem;
  font-weight: 600;
  padding: 0.5rem 0;
  position: relative;
  transition: color 0.3s ease;
}

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

.main-nav a:hover,
.main-nav a.active {
  color: var(--accent-color);
}

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

.hamburger-menu {
  display: none; /* Ẩn trên desktop */
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  z-index: 1001;
}

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

/* Animation for hamburger menu */
.hamburger-menu.open span:nth-child(1) {
  transform: translateY(8px) rotate(-45deg);
}

.hamburger-menu.open span:nth-child(2) {
  opacity: 0;
}

.hamburger-menu.open span:nth-child(3) {
  transform: translateY(-8px) rotate(45deg);
}

/* ==================== Footer ==================== */
.site-footer {
  background-color: var(--primary-color);
  color: var(--text-color);
  padding: 3rem 2rem 1rem;
  font-size: 0.95rem;
}

.footer-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  max-width: 1200px;
  margin: 0 auto 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-column h3 {
  color: var(--accent-color);
  margin-bottom: 1.2rem;
  font-size: 1.1rem;
  text-transform: uppercase;
}

.footer-logo {
  font-size: 1.8rem;
  font-weight: bold;
  color: var(--accent-color);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 1rem;
  display: block;
}

.footer-column p {
  margin-bottom: 0.8rem;
  line-height: 1.8;
}

.footer-column a {
  color: var(--text-color);
  transition: color 0.3s ease;
}

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

.footer-nav ul li {
  margin-bottom: 0.6rem;
}

.footer-bottom {
  text-align: center;
  padding-top: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.7);
}

/* ==================== Responsive ==================== */
@media (max-width: 768px) {
  .site-header {
    padding: 1rem;
  }

  .header-container {
    flex-wrap: wrap;
  }

  .main-nav {
    display: none; /* Ẩn menu chính theo mặc định trên mobile */
    flex-direction: column;
    width: 100%;
    background-color: var(--primary-color);
    position: absolute;
    top: 100%; /* Đặt dưới header */
    left: 0;
    right: 0;
    padding: 1rem 0;
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.3);
  }

  .main-nav.active {
    display: flex; /* Hiện menu khi active */
  }

  .main-nav ul {
    flex-direction: column;
    text-align: center;
    gap: 0;
  }

  .main-nav ul li {
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  }

  .main-nav ul li:last-child {
    border-bottom: none;
  }

  .main-nav a {
    display: block;
    padding: 1rem;
    width: 100%;
  }

  .main-nav a::after {
    display: none; /* Ẩn hiệu ứng gạch chân trên mobile */
  }

  .main-nav a:hover,
  .main-nav a.active {
    background-color: rgba(255, 255, 255, 0.1);
  }

  .hamburger-menu {
    display: block; /* Hiện hamburger trên mobile */
  }

  .footer-container {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .footer-column h3 {
    margin-top: 1.5rem;
  }

  .footer-logo {
    margin-left: auto;
    margin-right: auto;
  }

  .footer-nav ul {
    padding: 0;
  }
}