/* --- 1. RESET & VARIABLES (DARK THEME) --- */
:root {
    --bg-dark: #0B1120;
    --bg-card: #151e32;
    --primary: #3b82f6;
    --accent: #06b6d4;
    --text-main: #f3f4f6;
    --text-muted: #94a3b8;
    --grid-line: rgba(255, 255, 255, 0.05);
    --max-width: 1200px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.6;
    background-image:
        linear-gradient(var(--grid-line) 1px, transparent 1px),
        linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
    background-size: 40px 40px;
    min-height: 100vh;
}

a {
    text-decoration: none;
    color: inherit;
    transition: 0.3s;
}

ul {
    list-style: none;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* --- 2. NAVBAR (MENU) --- */
.navbar {
    background: rgba(11, 17, 32, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Style cho Logo ảnh */
.logo-img {
    height: 40px;
    /* Điều chỉnh chiều cao logo tại đây */
    width: auto;
}

.nav-links {
    display: flex;
    gap: 30px;
    align-items: center;
}

.nav-links a {
    font-size: 0.95rem;
    color: var(--text-muted);
}

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

.lang-btn {
    background: transparent;
    border: 1px solid var(--primary);
    color: var(--primary);
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s;
}

.lang-btn:hover {
    background: var(--primary);
    color: white;
    box-shadow: 0 0 10px var(--primary);
}

/* --- 3. HERO SECTION (LAYOUT MỚI) --- */
.hero-section {
    padding: 80px 0;
    background: radial-gradient(circle at center, rgba(59, 130, 246, 0.1) 0%, transparent 70%);
}

/* Flexbox container cho Hero */
.hero-container-flex {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 40px;
}

.hero-text-content {
    flex: 1;
    /* Chiếm phần còn lại */
}

.hero-image-box {
    flex: 0 0 350px;
    /* Chiều rộng cố định cho ảnh */
    display: flex;
    justify-content: center;
}

/* Style cho Avatar */
.my-avatar {
    width: 300px;
    height: 300px;
    object-fit: cover;
    border-radius: 50%;
    /* Bo tròn */
    border: 3px solid var(--primary);
    box-shadow: 0 0 25px rgba(59, 130, 246, 0.4);
    /* Phát sáng */
    transition: transform 0.3s;
}

.my-avatar:hover {
    transform: scale(1.05);
}

.hero-title {
    font-size: 2.5rem;
    margin-bottom: 16px;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-sub {
    font-size: 1.2rem;
    color: var(--text-muted);
    margin-bottom: 8px;
}

.hero-note {
    font-size: 0.9rem;
    color: var(--accent);
    margin-bottom: 30px;
    font-weight: 600;
}

.hero-buttons {
    display: flex;
    gap: 20px;
    margin-top: 20px;
}

/* Mobile Responsive cho Hero */
@media (max-width: 768px) {
    .hero-container-flex {
        flex-direction: column-reverse;
        /* Đảo ngược: Ảnh lên trên hoặc Text lên trên tùy thích */
        text-align: center;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-image-box {
        flex: auto;
        width: 100%;
        margin-bottom: 20px;
    }

    .my-avatar {
        width: 200px;
        height: 200px;
    }
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: 0.3s;
    display: flex;
    align-items: center;
    gap: 8px;
}

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

.btn-primary:hover {
    background: #2563eb;
}

.btn-outline {
    border: 1px solid var(--text-muted);
    color: var(--text-muted);
}

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

/* --- SECTIONS CHUNG --- */
.section-block {
    padding: 50px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.02);
}

.section-header {
    margin-bottom: 30px;
    color: var(--primary);
    font-size: 1.5rem;
    border-left: 4px solid var(--accent);
    padding-left: 15px;
}

.section-header.centered {
    border-left: none;
    text-align: center;
}

/* ABOUT */
.about-box {
    background: rgba(255, 255, 255, 0.03);
    padding: 30px;
    border-radius: 12px;
    border-left: 4px solid var(--primary);
}

.highlight-text {
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 15px;
}

/* SKILLS CARD */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
}

.skill-card {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.05);
    padding: 24px;
    border-radius: 12px;
    transition: 0.3s;
    position: relative;
    overflow: hidden;
}

.skill-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent);
}

.card-icon {
    font-size: 2rem;
    margin-bottom: 16px;
    display: inline-block;
    padding: 10px;
    background: rgba(59, 130, 246, 0.1);
    border-radius: 8px;
    color: var(--accent);
}

.skill-card h3 {
    margin-bottom: 12px;
    font-size: 1.25rem;
}

.skill-card ul li {
    position: relative;
    padding-left: 20px;
    margin-bottom: 8px;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.skill-card ul li::before {
    content: "•";
    color: var(--accent);
    position: absolute;
    left: 0;
    font-weight: bold;
}

.card-bar {
    height: 4px;
    width: 60px;
    background: var(--primary);
    margin-top: 16px;
    border-radius: 2px;
    transition: width 0.3s;
}

.skill-card:hover .card-bar {
    width: 100%;
    background: var(--accent);
}

/* GRID 2 COL (Cho mục 4 & 5) */
.grid-2-col {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

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

.check-list li,
.icon-list li {
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--text-muted);
}

.check-list li::before {
    content: "✔";
    color: var(--accent);
}

.icon-list i {
    font-size: 1.2rem;
    color: var(--primary);
}

/* FEATURE (Mục 6) */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.feature-card {
    background: var(--bg-card);
    padding: 30px;
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    transition: 0.3s;
}

.feature-card:hover {
    border-color: var(--primary);
    transform: translateY(-5px);
}

.mini-list {
    margin: 15px 0 25px 20px;
    list-style: circle;
    color: var(--text-muted);
}

.btn-sm {
    display: inline-block;
    padding: 8px 16px;
    border: 1px solid var(--primary);
    border-radius: 6px;
    font-size: 0.9rem;
    color: var(--primary);
}

.btn-sm:hover {
    background: var(--primary);
    color: #fff;
}

/* TAIWAN (Mục 7) */
.taiwan-box {
    text-align: center;
    background: linear-gradient(135deg, rgba(6, 182, 212, 0.1), rgba(59, 130, 246, 0.1));
    padding: 40px;
    border-radius: 16px;
    border: 1px dashed var(--accent);
}

.tw-benefits {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.badge {
    background: rgba(6, 182, 212, 0.2);
    color: var(--accent);
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
}

/* --- FOOTER MỚI --- */
footer {
    padding: 40px 0;
    margin-top: 40px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    background: #0f172a;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.social-links {
    display: flex;
    gap: 20px;
}

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-muted);
    font-size: 1.5rem;
    transition: 0.3s;
}

.social-links a:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(59, 130, 246, 0.4);
}

footer p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* --- STYLE CHO TRANG TÀI NGUYÊN (SALES PAGE) --- */

/* Product Box (Hộp sản phẩm chính) */
.product-box {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 16px;
    padding: 40px;
    display: flex;
    gap: 40px;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.highlight-border {
    border: 1px solid var(--accent);
    box-shadow: 0 0 20px rgba(6, 182, 212, 0.15);
    /* Hiệu ứng phát sáng */
}

.product-content {
    flex: 2;
}

.product-image {
    flex: 1;
    display: flex;
    justify-content: center;
}

/* Nhãn Premium */
.badge-premium {
    display: inline-block;
    background: linear-gradient(90deg, #f59e0b, #d97706);
    color: white;
    padding: 4px 12px;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: 1px;
}

.price-tag {
    margin-bottom: 20px;
    font-size: 1.1rem;
}

.free-tag {
    color: var(--text-muted);
    text-decoration: line-through;
}

.paid-tag {
    color: var(--accent);
    font-weight: 700;
    font-size: 1.4rem;
    margin-left: 10px;
}

.prod-desc p {
    margin-bottom: 8px;
    color: var(--text-main);
}

/* Nút bấm mua hàng hiệu ứng đặc biệt */
.glow-effect {
    box-shadow: 0 0 15px var(--primary);
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        box-shadow: 0 0 0 0 rgba(59, 130, 246, 0.7);
    }

    70% {
        box-shadow: 0 0 0 10px rgba(59, 130, 246, 0);
    }

    100% {
        box-shadow: 0 0 0 0 rgba(59, 130, 246, 0);
    }
}

.button-group {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

/* Hình mô phỏng sách */
.mockup-book {
    width: 200px;
    height: 280px;
    background: rgba(255, 255, 255, 0.05);
    border: 2px solid var(--text-muted);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
}

/* Danh sách tài liệu nhỏ */
.resource-list {
    margin-top: 20px;
}

.resource-item {
    display: flex;
    gap: 15px;
    padding: 15px;
    background: rgba(255, 255, 255, 0.03);
    margin-bottom: 10px;
    border-radius: 8px;
    transition: 0.3s;
}

.resource-item:hover {
    background: rgba(255, 255, 255, 0.08);
}

.resource-item h4 {
    font-size: 1rem;
    color: var(--text-main);
    margin-bottom: 4px;
}

.link-sm {
    font-size: 0.85rem;
    color: var(--accent);
    text-decoration: underline;
}

/* Upsell Banner */
.upsell-banner {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    padding: 40px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 30px;
}

.upsell-content h2 {
    color: white;
    margin-bottom: 8px;
    font-size: 1.5rem;
}

.upsell-content p {
    color: rgba(255, 255, 255, 0.9);
}

.btn-white {
    background: white;
    color: var(--primary);
    padding: 12px 24px;
    border-radius: 6px;
    font-weight: 700;
}

.btn-white:hover {
    transform: scale(1.05);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .product-box {
        flex-direction: column-reverse;
        text-align: center;
    }

    .button-group {
        justify-content: center;
        flex-direction: column;
    }

    .upsell-banner {
        flex-direction: column;
        text-align: center;
    }

    .grid-2-col {
        grid-template-columns: 1fr;
    }
}