/* Biến CSS */
:root {
    --primary-color: #1A2E4E;
    --secondary-color: #FFD700;
    --text-color: #f0f0f0;
    --link-color: #FFD700;
    --hover-color: #fff;
    --bg-dark: #0f1a2e;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: #f4f4f4; /* Nền trang tổng thể */
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

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

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

ul {
    list-style: none;
}

/* Header */
.site-header {
    background-color: var(--primary-color);
    color: var(--text-color);
    padding: 15px 0;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.logo {
    font-size: 2.2em;
    font-weight: bold;
    color: var(--secondary-color);
    text-transform: uppercase;
    letter-spacing: 1px;
    padding: 5px 0;
    text-shadow: 1px 1px 3px rgba(0,0,0,0.3);
}

.logo:hover {
    color: var(--hover-color);
}

.main-nav ul {
    display: flex;
}

.main-nav li {
    margin-left: 30px;
}

.main-nav a {
    color: var(--text-color);
    font-weight: 500;
    padding: 10px 0;
    display: block;
    transition: color 0.3s ease;
    position: relative;
}

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

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

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 10px;
    z-index: 1001;
}

.hamburger {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--secondary-color);
    position: relative;
    transition: background-color 0.3s ease;
}

.hamburger::before, .hamburger::after {
    content: '';
    display: block;
    width: 100%;
    height: 3px;
    background-color: var(--secondary-color);
    position: absolute;
    transition: transform 0.3s ease;
}

.hamburger::before {
    top: -8px;
}

.hamburger::after {
    bottom: -8px;
}

.nav-toggle.active .hamburger {
    background-color: transparent;
}

.nav-toggle.active .hamburger::before {
    transform: translateY(8px) rotate(45deg);
}

.nav-toggle.active .hamburger::after {
    transform: translateY(-8px) rotate(-45deg);
}

.header-actions {
    margin-left: auto;
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    border-radius: 5px;
    font-weight: bold;
    text-align: center;
    transition: background-color 0.3s ease, color 0.3s ease;
}

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

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

/* Footer */
.site-footer {
    background-color: var(--primary-color);
    color: var(--text-color);
    padding: 40px 0 20px;
    font-size: 0.9em;
}

.footer-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-bottom: 30px;
}

.footer-heading {
    font-size: 1.3em;
    color: var(--secondary-color);
    margin-bottom: 15px;
    text-transform: uppercase;
}

.footer-col p {
    line-height: 1.8;
    color: #ccc;
}

.footer-nav ul li {
    margin-bottom: 8px;
}

.footer-nav a, .contact-info a, .contact-info li {
    color: #ccc;
    transition: color 0.3s ease;
}

.footer-nav a:hover, .contact-info a:hover {
    color: var(--secondary-color);
}

.contact-info li {
    margin-bottom: 8px;
    display: flex;
    align-items: center;
}

.contact-info li a {
    margin-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.copyright {
    color: #aaa;
}

/* Responsive */
@media (max-width: 992px) {
    .main-nav ul {
        margin-left: 15px;
    }
    .main-nav li {
        margin-left: 20px;
    }
}

@media (max-width: 768px) {
    .site-header .container {
        flex-wrap: nowrap;
    }
    .nav-toggle {
        display: block;
        order: 2; /* Đảm bảo nút hamburger ở bên phải */
    }
    .logo {
        order: 1;
        flex-grow: 1;
    }
    .header-actions {
        order: 3;
        margin-left: 15px;
    }
    .main-nav {
        flex-basis: 100%;
        order: 4;
        display: none;
        width: 100%;
        text-align: center;
        background-color: var(--primary-color);
        box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
        padding: 20px 0;
        margin-top: 15px; /* Khoảng cách với header */
    }
    .main-nav.active {
        display: block;
    }
    .main-nav ul {
        flex-direction: column;
        align-items: center;
    }
    .main-nav li {
        margin: 10px 0;
    }
    .main-nav a {
        padding: 10px 20px;
        width: 100%;
    }
    .main-nav a::after {
        left: 50%;
        transform: translateX(-50%);
    }
    .footer-columns {
        grid-template-columns: 1fr;
        text-align: center;
    }
    .footer-col {
        margin-bottom: 20px;
    }
    .footer-col:last-child {
        margin-bottom: 0;
    }
    .contact-info li {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .logo {
        font-size: 1.8em;
    }
    .header-actions .btn {
        padding: 8px 15px;
        font-size: 0.9em;
    }
    .site-header .container {
        padding: 0 15px;
    }
    .site-footer .container {
        padding: 0 15px;
    }
}