/* =========================================================
   1. CẤU HÌNH BIẾN & TỔNG QUAN
   ========================================================= */
:root {
    --primary-color: #0b8457;       /* Màu xanh lá mạ đậm */
    --primary-dark: #065f3e;        
    --secondary-color: #008080;
    --accent-color: #e67e22;
    --text-main: #222222;
    --text-muted: #666666;
    --border-color: #e0e8e4;
    --bg-light: #f8f9fa;
}

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background-color: #ffffff;
    color: var(--text-main);
    margin: 0;
    padding: 0;
    line-height: 1.6;
}

/* =========================================================
   2. THANH ĐIỀU HƯỚNG CỐ ĐỊNH (HEADER NAVBAR)
   ========================================================= */
.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 5%;
    background: #ffffff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.logo-landing {
    font-size: 22px;
    font-weight: 800;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-links {
    display: flex;
    gap: 25px;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-links a {
    text-decoration: none;
    color: #333;
    font-weight: 600;
    font-size: 15px;
    transition: color 0.2s ease;
}

.nav-links a:hover {
    color: var(--primary-color);
}

/* KHUNG ĐĂNG NHẬP */
.login-bar-top {
    display: flex;
    align-items: center;
    gap: 8px;
}

.login-bar-top input {
    padding: 8px 12px;
    border: 1px solid #ccc;
    border-radius: 6px;
    font-size: 13.5px;
    outline: none;
    background: #fdfdfd;
}

.login-bar-top button {
    padding: 8px 18px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 6px;
    font-weight: bold;
    cursor: pointer;
    font-size: 13.5px;
    white-space: nowrap;
    transition: background 0.2s ease;
}

.login-bar-top button:hover { 
    background: var(--primary-dark); 
}

/* =========================================================
   3. HERO BANNER CỐ ĐỊNH
   ========================================================= */
.hero-banner-full {
    width: 100%;
    overflow: hidden;
    display: block;
    line-height: 0;
}

.hero-banner-full img {
    width: 100%;
    height: auto;
    display: block;
    object-fit: cover;
}

/* =========================================================
   4. BỐ CỤC NỘI DUNG CĂN GIỮA (MAIN CONTENT INDEX)
   ========================================================= */
.main-container {
    max-width: 1000px;
    margin: 40px auto;
    padding: 0 20px;
    text-align: center;
}

.page-title {
    font-size: 34px;
    font-weight: 800;
    color: var(--primary-color);
    margin-top: 0;
    margin-bottom: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    text-align: center;
}

.page-subtitle {
    font-size: 16px;
    color: var(--text-muted);
    margin-bottom: 35px;
    text-align: center;
}

/* LƯỚI DANH SÁCH BÀI VIẾT INDEX */
.grid-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    justify-content: center;
    margin-bottom: 40px;
}

.card-item {
    background: #ffffff;
    border: 2px solid var(--border-color);
    border-radius: 16px;
    padding: 20px 15px;
    text-decoration: none;
    color: var(--text-main);
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.03);
}

.card-item:hover {
    transform: translateY(-5px);
    border-color: var(--primary-color);
    box-shadow: 0 8px 20px rgba(11, 132, 87, 0.15);
}

.card-item img {
    width: 100%;
    max-width: 160px;
    height: 100px;
    object-fit: cover;
    border-radius: 10px;
    margin-bottom: 15px;
    border: 1px solid #eee;
}

.card-item-title {
    font-size: 18px;
    font-weight: 700;
    color: #111111;
    margin-bottom: 8px;
}

.card-item-desc {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.4;
    text-align: center;
}

/* =========================================================
   5. BỐ CỤC NỘI DUNG BÀI VIẾT CHI TIẾT (ARTICLE DETAIL)
   ========================================================= */
.container {
    max-width: 860px;
    margin: 30px auto;
    background: #ffffff;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.article-header {
    border-bottom: 2px solid var(--bg-light);
    padding-bottom: 20px;
    margin-bottom: 30px;
}

.article-header h1 {
    color: var(--primary-color);
    font-size: 28px;
    line-height: 1.3;
    margin-bottom: 15px;
}

.meta-description {
    font-size: 16px;
    font-style: italic;
    color: #555;
    background: var(--bg-light);
    padding: 15px;
    border-left: 4px solid var(--primary-color);
    margin-bottom: 20px;
}

.keywords-box {
    font-size: 13px;
    color: #666;
    background: #f0f4f8;
    padding: 10px 15px;
    border-radius: 6px;
    word-wrap: break-word;
}

article h2 {
    color: var(--primary-color);
    font-size: 22px;
    margin-top: 35px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 8px;
}

article h3 {
    color: var(--secondary-color);
    font-size: 18px;
    margin-top: 25px;
}

article p {
    margin-bottom: 18px;
    text-align: justify;
}

article ul, article ol {
    margin-bottom: 20px;
    padding-left: 25px;
}

article li {
    margin-bottom: 8px;
}

.highlight-box {
    background-color: #eef7ff;
    border: 1px solid #b6d4fe;
    padding: 18px;
    border-radius: 8px;
    margin: 20px 0;
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    margin: 25px 0;
    font-size: 15px;
}

.comparison-table th, .comparison-table td {
    border: 1px solid var(--border-color);
    padding: 12px 15px;
    text-align: left;
}

.comparison-table th {
    background-color: var(--primary-color);
    color: #ffffff;
}

.comparison-table tr:nth-child(even) {
    background-color: var(--bg-light);
}

.faq-item {
    margin-bottom: 20px;
    background: var(--bg-light);
    padding: 15px 20px;
    border-radius: 8px;
}

.faq-question {
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 8px;
}

.cta-container {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: #ffffff;
    padding: 30px;
    border-radius: 10px;
    text-align: center;
    margin-top: 40px;
}

.cta-container h3 {
    color: #ffffff;
    font-size: 22px;
    margin-top: 0;
}

.cta-container p {
    text-align: center;
    font-size: 16px;
    margin-bottom: 20px;
}

.cta-btn {
    display: inline-block;
    background-color: var(--accent-color);
    color: #ffffff;
    font-weight: bold;
    font-size: 16px;
    padding: 12px 30px;
    border-radius: 25px;
    text-decoration: none;
    transition: background 0.3s ease;
}

.cta-btn:hover {
    background-color: #d35400;
}

/* =========================================================
   6. FOOTER (CHÙNG CHO CẢ LANDING VÀ BÀI VIẾT)
   ========================================================= */
.landing-footer { 
    background: #111; 
    color: #fff; 
    padding: 25px 5%; 
    display: flex; 
    justify-content: space-between; 
    align-items: center; 
    font-size: 13px; 
    margin-top: 50px;
}

.footer-brand-socials {
    display: flex;
    align-items: center;
    gap: 15px;
}

.footer-social-icons {
    display: flex;
    align-items: center;
    gap: 10px;
}

.footer-social-icons img {
    width: 24px;
    height: 24px;
    object-fit: contain;
}

/* =========================================================
   7. RESPONSIVE
   ========================================================= */
@media (max-width: 850px) {
    .grid-container {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 600px) {
    .navbar { flex-direction: column; gap: 12px; }
    .login-bar-top { width: 100%; flex-direction: column; }
    .login-bar-top input, .login-bar-top button { width: 100%; }
    .grid-container { grid-template-columns: 1fr; }
    .page-title { font-size: 24px; }
    .landing-footer { flex-direction: column; gap: 15px; text-align: center; }
    .container { padding: 20px; margin: 10px; }
}