:root {
    --primary-blue: #0d6efd;
    --primary-blue-dark: #0b5ed7;
    --secondary-blue: #e7f3ff;
    --text-dark: #212529;
    --text-light: #6c757d;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #dee2e6;
    --success-color: #198754;
}

* {
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    margin: 0;
    color: var(--text-dark);
    line-height: 1.6;
    background-color: var(--bg-white);
}

.container {
    max-width: 1140px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

section {
    padding: 60px 0;
}

.btn {
    display: inline-block;
    padding: 12px 28px;
    font-weight: 600;
    font-size: 1rem;
    text-decoration: none;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.btn-primary {
    background-color: var(--primary-blue);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-blue-dark);
    transform: translateY(-2px);
}

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

.btn-secondary:hover {
    background-color: #f1f1f1;
    border-color: var(--text-dark);
}

#login-btn {
    color: #f1f1f1;
}
#login-btn:hover {
    color: var(--text-dark);
}

/*HERO*/
.hero {
    position: relative;
    background-image: url("/static/img/hero_background.png");
    background-size: cover;
    background-position: center right;
    background-repeat: no-repeat;
    min-height: 100vh;

    display: flex;
    align-items: center;
    color: white;
    text-align: left;
    padding: 100px 0;
    z-index: 1;
}

.hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(to right, rgba(0, 0, 0, 0.65), rgba(0, 0, 0, 0.2));
    z-index: 0;
}

.hero .container {
    position: relative;
    z-index: 2;
}

.hero h1, .hero h2 {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1rem;
}

.hero .subtitle {
    font-size: 1.25rem;
    color: #e5e7eb;
    max-width: 600px;
    margin-bottom: 2rem;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.social-proof {
    background-color: var(--bg-white);
    text-align: center;
    padding: 40px 0;
    border-bottom: 1px solid var(--border-color);
}

.social-proof p {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.problem-solution {
    background: var(--bg-white);
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
    align-items: center;
}

@media(min-width: 768px) {
    .grid-2 {
        grid-template-columns: 1fr 1fr;
    }
}

.problem-solution ul {
    list-style: none;
    padding: 0;
}

.problem-solution li {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1rem;
}

.problem-solution .icon {
    font-size: 1.5rem;
}

.problem-solution .icon.problem {
    color: #dc3545;
}

.problem-solution .icon.solution {
    color: var(--success-color);
}

.how-it-works {
    background-color: var(--bg-light);
    text-align: center;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: 2.5rem;
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.step-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
}

.step-card .step-number {
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary-blue);
}

/* === Footer === */
.site-footer {
    background-color: #111827;
    color: #9ca3af;
    padding: 60px 0 20px;
    font-size: 0.95rem;
}

.footer-content {
    display: grid;
    /* NÂNG CẤP: Chia 4 cột linh hoạt */
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 2rem;
    padding-bottom: 2rem;
    margin-bottom: 2rem;
    border-bottom: 1px solid #374151;
}

.footer-column h3, .footer-column h4 {
    color: #ffffff;
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.footer-column.footer-about p {
    line-height: 1.7;
    max-width: 350px;
    margin-bottom: 1.5rem;
}

.footer-column.footer-contact p {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
}

.footer-column a {
    display: block;
    color: #9ca3af;
    text-decoration: none;
    transition: color 0.2s ease;
    margin-bottom: 0.75rem;
}

.footer-column a:hover {
    color: #ffffff;
}

.social-icons {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}
.social-icons a {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 40px;
    height: 40px;
    background-color: #374151;
    color: #ffffff;
    border-radius: 50%;
    font-size: 1.1rem;
}
.social-icons a:hover {
    background-color: var(--primary-blue);
}

.footer-bottom {
    text-align: center;
    font-size: 0.9rem;
}
.footer-bottom p {
    margin: 0;
}

.certifications {
    margin-top: 1.5rem;
}
.certifications img {
    max-height: 45px; /* Điều chỉnh kích thước logo BCT cho phù hợp */
    width: auto;
}


/* Responsive cho Footer */
@media (max-width: 768px) {
    .footer-content {
        grid-template-columns: 1fr; /* Chuyển thành 1 cột trên mobile */
        text-align: center;
    }
    .footer-column.footer-about p {
        margin-left: auto;
        margin-right: auto;
    }
    .footer-column.footer-contact p {
        justify-content: center;
    }
    .social-icons {
        justify-content: center;
    }
}

@media (max-width: 576px) {
    .hero h1, .hero h2 {
        font-size: 2rem;
    }

    .hero .subtitle {
        font-size: 1rem;
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.95rem;
    }
}