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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #121212; /* Nền tối sang trọng */
    color: #e0e0e0; /* Chữ màu sáng */
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

/* Header Styles */
header {
    text-align: center;
    margin-bottom: 30px;
    padding-top: 20px;
}

h1 {
    color: #ffffff;
    font-size: 2.5rem;
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.subtitle {
    color: #a0a0a0;
    font-size: 1.2rem;
}

/* CTA Button Styles (Quan trọng nhất) */
.cta-container {
    text-align: center;
    margin: 40px 0;
}

.download-btn {
    display: inline-block;
    background-color: #00c853; /* Màu xanh lá nổi bật (Action color) */
    color: #ffffff;
    text-decoration: none;
    padding: 20px 40px;
    border-radius: 50px; /* Bo tròn nút */
    font-size: 1.5rem;
    font-weight: bold;
    box-shadow: 0 4px 15px rgba(0, 200, 83, 0.4);
    transition: transform 0.2s, background-color 0.2s, box-shadow 0.2s;
    border: 2px solid #00e676;
    width: 100%;
    max-width: 500px;
}

.download-btn:hover {
    background-color: #00e676;
    transform: scale(1.05); /* Phóng to nhẹ khi di chuột */
    box-shadow: 0 6px 20px rgba(0, 200, 83, 0.6);
}

.btn-icon {
    margin-right: 10px;
    font-size: 1.8rem;
    vertical-align: middle;
}

.btn-sub {
    display: block;
    font-size: 0.9rem;
    font-weight: normal;
    opacity: 0.9;
    margin-top: 5px;
}

.small-btn {
    font-size: 1.2rem;
    padding: 15px 30px;
    background-color: #d50000; /* Màu đỏ cho nút phụ dưới cùng */
    border-color: #ff1744;
    box-shadow: 0 4px 15px rgba(213, 0, 0, 0.4);
}
.small-btn:hover {
    background-color: #ff1744;
}

/* Content Styles */
main {
    background-color: #1e1e1e;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

h2 {
    color: #4fc3f7; /* Màu xanh dương nhạt cho tiêu đề phụ */
    margin-top: 30px;
    margin-bottom: 15px;
    border-bottom: 1px solid #333;
    padding-bottom: 10px;
}

p {
    margin-bottom: 15px;
    text-align: justify;
}

ul {
    margin-bottom: 20px;
    padding-left: 20px;
}

li {
    margin-bottom: 10px;
}

strong {
    color: #ffffff;
}

/* Footer */
footer {
    text-align: center;
    margin-top: 40px;
    padding: 20px;
    border-top: 1px solid #333;
    color: #757575;
    font-size: 0.9rem;
}

footer a {
    color: #757575;
    text-decoration: none;
}

/* Mobile Responsive */
@media (max-width: 600px) {
    h1 {
        font-size: 1.8rem;
    }
    
    .download-btn {
        padding: 15px 20px;
        font-size: 1.2rem;
    }
    
    .container {
        padding: 10px;
    }
    
    main {
        padding: 20px;
    }
}