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

:root {
    --primary-color: #1DA1F2;
    --secondary-color: #14171A;
    --light-color: #E1E8ED;
    --dark-color: #14171A;
    --accent-color: #657786;
    --white: #FFFFFF;
    --section-padding: 70px 0;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--secondary-color);
    background-color: var(--white);
}

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

a {
    text-decoration: none;
    color: var(--primary-color);
    transition: all 0.3s ease;
}

a:hover {
    color: #0d8ecf;
}

img {
    max-width: 100%;
    height: auto;
}

.placeholder-img {
    background-color: #f1f1f1;
    border-radius: 8px;
    min-height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent-color);
    font-size: 14px;
}

/* Thiết lập tỷ lệ khung hình 9:16 (chiều dọc) cho video */
video.placeholder-img {
    height: 600px;
    width: 337.5px; /* Tính theo tỷ lệ 9:16 từ chiều cao 600px */
    object-fit: cover;
    margin: 0 auto;
    display: block;
}

.btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: var(--white);
    padding: 12px 25px;
    border-radius: 30px;
    font-weight: 600;
    font-size: 16px;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.btn:hover {
    background-color: #0d8ecf;
    color: var(--white);
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(29, 161, 242, 0.3);
}

.btn-yellow {
    background-color: #FFD700;
    color: var(--secondary-color);
}

.btn-yellow:hover {
    background-color: #FFC800;
    color: var(--secondary-color);
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(255, 215, 0, 0.3);
}

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

.button-group .btn i {
    margin-right: 8px;
}

.section {
    padding: var(--section-padding);
}

.bg-light {
    background-color: #f8f9fa;
}

.bg-dark {
    background-color: var(--secondary-color);
    color: var(--white);
}

h2 {
    font-size: 36px;
    margin-bottom: 30px;
    position: relative;
    padding-bottom: 15px;
}

h2:after {
    content: '';
    position: absolute;
    width: 60px;
    height: 4px;
    background-color: var(--primary-color);
    bottom: 0;
    left: 0;
}

.content-box {
    background-color: var(--white);
    border-radius: 8px;
    padding: 30px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

/* Benefits Grid */
.benefits-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
    margin-top: 20px;
    margin-bottom: 10px;
}

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

.benefit-item {
    display: flex;
    background-color: #f8f9fa;
    border-radius: 8px;
    padding: 20px;
    transition: all 0.3s ease;
    border-bottom: 3px solid transparent;
}

.benefit-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.05);
    border-bottom: 3px solid var(--primary-color);
}

.benefit-icon {
    color: var(--primary-color);
    font-size: 24px;
    margin-right: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 40px;
}

.benefit-content h4 {
    margin: 0 0 8px 0;
    font-size: 18px;
    color: var(--secondary-color);
}

.benefit-content p {
    margin: 0;
    font-size: 14px;
    color: var(--accent-color);
    line-height: 1.4;
}

/* Header */
header {
    background-color: var(--white);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

/* Prevent scrolling when mobile menu is open */
body.menu-open {
    overflow: hidden;
}

/* Mobile Menu Toggle Button */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 24px;
    color: var(--primary-color);
    cursor: pointer;
    transition: all 0.3s ease;
    padding: 5px;
    z-index: 110;
}

.mobile-menu-toggle:hover {
    color: var(--secondary-color);
}

.mobile-menu-toggle:focus {
    outline: none;
}

.logo {
    display: flex;
    align-items: center;
}

.logo i {
    font-size: 28px;
    color: var(--primary-color);
    margin-right: 10px;
}

.logo h1 {
    font-size: 22px;
    font-weight: 700;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

nav ul {
    display: flex;
    list-style: none;
    flex-wrap: nowrap;
}

nav ul li {
    margin-left: 25px;
}

nav ul li a {
    color: var(--secondary-color);
    font-weight: 600;
    position: relative;
}

nav ul li a:hover {
    color: var(--primary-color);
}

nav ul li a:after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    bottom: -5px;
    left: 0;
    transition: width 0.3s ease;
}

nav ul li a:hover:after {
    width: 100%;
}

/* Hero Section */
.hero {
    background-color: #f8f9fa;
    padding: 100px 0;
    overflow: hidden;
}

.hero .container {
    display: flex;
    align-items: center;
}

.hero-content {
    flex: 1;
    padding-right: 50px;
}

.hero-content h2 {
    font-size: 48px;
    line-height: 1.2;
    margin-bottom: 20px;
    padding-bottom: 0;
}

.hero-content h2:after {
    display: none;
}

.hero-content p {
    font-size: 18px;
    margin-bottom: 30px;
    color: var(--accent-color);
}

.hero-image {
    flex: 1;
    position: relative;
}

/* Steps Sections */
.step-grid {
    display: flex;
    align-items: center;
    gap: 50px;
    margin-top: 30px;
}

.step-grid.reverse {
    flex-direction: row-reverse;
}

.step-content, .step-image {
    flex: 1;
}

.step-content h3 {
    font-size: 24px;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.step-content ul, .step-content ol {
    margin-left: 20px;
    margin-bottom: 20px;
}

.step-content li {
    margin-bottom: 10px;
}

.numbered-list li {
    margin-bottom: 25px;
}

.numbered-list h4 {
    font-size: 18px;
    margin-bottom: 5px;
    color: var(--secondary-color);
}

/* Tips Section */
.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.tip-card {
    background-color: var(--white);
    border-radius: 8px;
    padding: 30px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    transition: all 0.3s ease;
}

.tip-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
}

.tip-icon {
    font-size: 30px;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.tip-card h3 {
    font-size: 20px;
    margin-bottom: 15px;
}

/* FAQ Section */
.faq-container {
    margin-top: 30px;
}

.faq-item {
    background-color: var(--white);
    border-radius: 8px;
    margin-bottom: 15px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
    overflow: hidden;
}

.faq-question {
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.faq-question:hover {
    background-color: #f8f9fa;
}

.faq-question h3 {
    margin: 0;
    font-size: 18px;
    font-weight: 600;
    color: var(--secondary-color);
}

.faq-question i {
    color: var(--primary-color);
    transition: transform 0.3s ease;
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

.faq-answer {
    padding: 0;
    max-height: 0;
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-item.active .faq-answer {
    padding: 0 20px 20px;
    max-height: 1000px;
}

.note-box {
    background-color: #f8f9fa;
    border-left: 4px solid var(--primary-color);
    padding: 15px 20px;
    margin-top: 20px;
    border-radius: 0 8px 8px 0;
}

.note-box h4 {
    margin-top: 0;
    color: var(--primary-color);
}

/* CTA Section */
.cta {
    text-align: center;
    padding: 100px 0;
}

.cta h2 {
    font-size: 36px;
    margin-bottom: 20px;
}

.cta h2:after {
    left: 50%;
    transform: translateX(-50%);
}

.cta p {
    font-size: 18px;
    margin-bottom: 30px;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* Footer */
footer {
    background-color: var(--secondary-color);
    color: var(--white);
    padding: 70px 0 20px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    margin-bottom: 50px;
}

.footer-logo {
    display: flex;
    align-items: center;
    margin-bottom: 20px;
}

.footer-logo i {
    font-size: 24px;
    color: var(--primary-color);
    margin-right: 10px;
}

.footer-links, .footer-resources {
    margin-bottom: 30px;
}

.footer-links h4, .footer-resources h4 {
    font-size: 18px;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
}

.footer-links h4:after, .footer-resources h4:after {
    content: '';
    position: absolute;
    width: 40px;
    height: 3px;
    background-color: var(--primary-color);
    bottom: 0;
    left: 0;
}

.footer-links ul, .footer-resources ul {
    list-style: none;
}

.footer-links ul li, .footer-resources ul li {
    margin-bottom: 10px;
}

.footer-links ul li a, .footer-resources ul li a {
    color: var(--light-color);
}

.footer-links ul li a:hover, .footer-resources ul li a:hover {
    color: var(--primary-color);
}

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

/* Responsive */
@media (max-width: 992px) {
    .hero .container {
        flex-direction: column;
    }
    
    .hero-content {
        padding-right: 0;
        margin-bottom: 50px;
        text-align: center;
    }
    
    .hero-content h2:after {
        display: block;
        left: 50%;
        transform: translateX(-50%);
    }
    
    .step-grid {
        flex-direction: column;
    }
    
    .step-grid.reverse {
        flex-direction: column;
    }
    
    .step-image {
        order: -1;
        margin-bottom: 30px;
    }
}

@media (max-width: 768px) {
    header .container {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }
    
    .logo {
        margin-bottom: 0;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .main-nav {
        position: fixed;
        top: 0;
        right: -280px;
        width: 280px;
        height: 100vh;
        background-color: var(--white);
        box-shadow: -5px 0 15px rgba(0, 0, 0, 0.1);
        padding: 80px 20px 30px;
        transition: right 0.3s ease;
        z-index: 100;
        overflow-y: auto;
    }
    
    .main-nav.active {
        right: 0;
    }
    
    .main-nav ul {
        flex-direction: column;
        width: 100%;
        padding: 0;
        margin: 0;
    }
    
    .main-nav ul li {
        margin: 0 0 15px 0;
    }
    
    .main-nav ul li a {
        font-size: 16px;
        display: block;
        padding: 10px 0;
        border-bottom: 1px solid #eee;
    }
    
    .overlay {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0, 0, 0, 0.5);
        z-index: 90;
    }
    
    .overlay.active {
        display: block;
    }
    
    h2 {
        font-size: 30px;
    }
    
    .hero-content h2 {
        font-size: 36px;
    }
    
    .footer-content {
        flex-direction: column;
    }
    
    .button-group {
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .button-group .btn {
        width: 100%;
        text-align: center;
        justify-content: center;
    }
}