/*Cấu trúc tổ chức:

0. CSS Variables - Tất cả biến màu sắc, kích thước  
1. Base Styles - Reset CSS và styles cơ bản cho body
2. Video Background - Video nền và overlay
3. Header & Navigation - Header cố định và menu điều hướng
4. Hero Section - Phần giới thiệu chính với search form
5. Features Section - Phần tính năng với grid layout
6. Contact Section - Phần thông tin liên hệ
7. Footer - Chân trang
8. Floating Elements - Các phần tử trang trí động
9. Animations - Các hiệu ứng animation
10. Responsive Design - Responsive cho mobile/tablet*/

/*=======================================================================================*/
/*                                    CSS VARIABLES                                     */
/*=======================================================================================*/
/* Chưa có CSS variables - có thể thêm vào để quản lý màu sắc và kích thước tốt hơn */

/*=======================================================================================*/
/*                                    BASE STYLES                                       */
/*=======================================================================================*/
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    overflow-x: hidden;
}

/*=======================================================================================*/
/*                                  VIDEO BACKGROUND                                    */
/*=======================================================================================*/
/* Video nền cố định toàn màn hình */
.video-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    object-fit: cover;
}

/* Lớp phủ gradient trên video */
.video-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(0, 0, 0, 0.6), rgba(30, 144, 255, 0.4));
    z-index: -1;
}

/*=======================================================================================*/
/*                                HEADER & NAVIGATION                                   */
/*=======================================================================================*/
/* Header cố định với hiệu ứng blur */
.header {
    position: fixed;
    top: 0;
    width: 100%;
    padding: 20px 0;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    z-index: 1000;
    transition: all 0.3s ease;
}

/* Header khi scroll - thay đổi màu nền */
.header.scrolled {
    background: rgba(0, 0, 0, 0.9);
    backdrop-filter: blur(20px);
}

/* Container chứa navigation */
.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
}

/* Logo với hiệu ứng text shadow */
.logo {
    font-size: 32px;
    font-weight: 800;
    color: #fff;
    text-decoration: none;
    text-shadow: 0 0 20px rgba(255, 255, 255, 0.5);
}

.logo span {
    color: #ff6b6b;
}

/* Menu navigation */
.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
    align-items: center;
}

/* Links trong menu với hiệu ứng hover */
.nav-link {
    color: #fff;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.nav-link:hover {
    color: #ff6b6b;
    transform: translateY(-2px);
}

/* Underline animation cho nav links */
.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
    transition: width 0.3s ease;
}

.nav-link:hover::after {
    width: 100%;
}

/* Nút login với gradient */
.login-btn {
    padding: 12px 25px;
    background: linear-gradient(45deg, #ff6b6b, #ff8e53);
    color: white;
    text-decoration: none;
    border-radius: 50px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 20px rgba(255, 107, 107, 0.3);
}

.login-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(255, 107, 107, 0.5);
    color: white;
}

/* Menu toggle cho mobile */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 3px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: white;
    transition: 0.3s;
}
/* Nút nhạc */
.btn-audio {
    background: #f3f4f6; /* Màu nền nhạt */
    border: 1px solid #ced4da;
    border-radius: 20px;
    color: #333;
    padding: 6px 12px;
    transition: all 0.3s ease;
    font-weight: 500;
}

.btn-audio i {
    color: #6f42c1; /* Tím pastel */
    font-size: 1rem;
    transition: transform 0.3s ease;
}

.btn-audio:hover {
    background: #e0e7ff; /* Màu hover dịu nhẹ */
    border-color: #a5b4fc;
    color: #111;
    transform: scale(1.03);
}

.btn-audio:hover i {
    transform: rotate(10deg) scale(1.1);
}


/*=======================================================================================*/
/*                                   HERO SECTION                                       */
/*=======================================================================================*/
/* Hero section toàn màn hình */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: white;
    position: relative;
}

/* Nội dung chính của hero */
.hero-content {
    max-width: 800px;
    padding: 0 20px;
    animation: fadeInUp 1s ease-out;
}

/* Subtitle nhỏ */
.hero h6 {
    font-size: 18px;
    color: #4ecdc4;
    margin-bottom: 15px;
    font-weight: 400;
    letter-spacing: 1px;
}

/* Tiêu đề chính với text shadow */
.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 20px;
    line-height: 1.2;
    text-shadow: 0 0 30px rgba(255, 255, 255, 0.3);
}

/* Text gradient cho emphasis */
.hero h1 em {
    color: #ff6b6b;
    font-style: normal;
    background: linear-gradient(45deg, #ff6b6b, #ff8e53);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero h1 span {
    color: #4ecdc4;
}

/* Mô tả hero */
.hero p {
    font-size: 1.2rem;
    margin-bottom: 40px;
    opacity: 0.9;
    line-height: 1.6;
}

/* Form tìm kiếm */
.search-form {
    display: flex;
    max-width: 600px;
    margin: 0 auto;
    gap: 15px;
    flex-wrap: wrap;
    justify-content: center;
}

/* Input tìm kiếm với backdrop blur */
.search-input {
    flex: 1;
    min-width: 300px;
    padding: 18px 25px;
    border: none;
    border-radius: 50px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    color: white;
    font-size: 16px;
    border: 2px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.search-input::placeholder {
    color: rgba(255, 255, 255, 0.7);
}

.search-input:focus {
    outline: none;
    border-color: #4ecdc4;
    box-shadow: 0 0 30px rgba(78, 205, 196, 0.3);
    background: rgba(255, 255, 255, 0.15);
}

/* Nút tìm kiếm */
.search-btn {
    padding: 18px 35px;
    background: linear-gradient(45deg, #4ecdc4, #44a08d);
    color: white;
    border: none;
    border-radius: 50px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 20px rgba(78, 205, 196, 0.3);
}

.search-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(78, 205, 196, 0.5);
}

/*=======================================================================================*/
/*                                 FEATURES SECTION                                     */
/*=======================================================================================*/
/* Section tính năng */
.features {
    padding: 100px 0;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(20px);
}

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

/* Tiêu đề section */
.section-title {
    text-align: center;
    margin-bottom: 80px;
    color: white;
}

.section-title h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 20px;
}

.section-title em {
    color: #ff6b6b;
    font-style: normal;
}

.section-title span {
    color: #4ecdc4;
}

/* Grid layout cho features */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

/* Card tính năng với hiệu ứng glassmorphism */
.feature-card {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 40px 30px;
    text-align: center;
    color: white;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

/* Hiệu ứng shine khi hover */
.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.1), transparent);
    transition: left 0.5s ease;
}

.feature-card:hover::before {
    left: 100%;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
    border-color: rgba(255, 255, 255, 0.3);
}

/* Icon với gradient text */
.feature-icon {
    font-size: 3rem;
    margin-bottom: 20px;
    background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.feature-card h4 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 15px;
}

.feature-card p {
    opacity: 0.8;
    line-height: 1.6;
}

/*=======================================================================================*/
/*                                 CONTACT SECTION                                      */
/*=======================================================================================*/
/* Section liên hệ */
.contact {
    padding: 100px 0;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
}

.contact-content {
    text-align: center;
    color: white;
}

.contact h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 20px;
}

.contact p {
    font-size: 1.1rem;
    margin-bottom: 30px;
    opacity: 0.9;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* Thông tin số điện thoại */
.phone-info {
    display: inline-flex;
    align-items: center;
    gap: 15px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 20px 30px;
    border-radius: 50px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.phone-info:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.phone-info i {
    color: #4ecdc4;
    font-size: 1.5rem;
}

.phone-info a {
    color: white;
    text-decoration: none;
    font-weight: 600;
}

/*=======================================================================================*/
/*                                     FOOTER                                           */
/*=======================================================================================*/
/* Chân trang */
.footer {
    padding: 50px 0;
    background: rgba(0, 0, 0, 0.9);
    backdrop-filter: blur(20px);
    text-align: center;
    color: white;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer p {
    opacity: 0.7;
}

.footer a {
    color: #4ecdc4;
    text-decoration: none;
}

/*=======================================================================================*/
/*                                FLOATING ELEMENTS                                     */
/*=======================================================================================*/
/* Container cho các phần tử trang trí */
.floating-elements {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

/* Các phần tử trang trí floating */
.floating-element {
    position: absolute;
    background: linear-gradient(45deg, rgba(255, 107, 107, 0.1), rgba(78, 205, 196, 0.1));
    border-radius: 50%;
    animation: float 15s infinite ease-in-out;
}

.floating-element:nth-child(1) {
    width: 80px;
    height: 80px;
    top: 20%;
    left: 10%;
    animation-delay: 0s;
}

.floating-element:nth-child(2) {
    width: 120px;
    height: 120px;
    top: 60%;
    right: 15%;
    animation-delay: 5s;
}

.floating-element:nth-child(3) {
    width: 60px;
    height: 60px;
    bottom: 30%;
    left: 20%;
    animation-delay: 10s;
}

/*=======================================================================================*/
/*                                   ANIMATIONS                                         */
/*=======================================================================================*/
/* Animation fade in up cho hero content */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Animation floating cho các phần tử trang trí */
@keyframes float {
    0%, 100% {
        transform: translateY(0px) rotate(0deg);
        opacity: 0.3;
    }
    33% {
        transform: translateY(-30px) rotate(120deg);
        opacity: 0.6;
    }
    66% {
        transform: translateY(30px) rotate(240deg);
        opacity: 0.4;
    }
}

/*=======================================================================================*/
/*                                RESPONSIVE DESIGN                                     */
/*=======================================================================================*/
/* Responsive cho tablet và mobile */
@media (max-width: 768px) {
    /* Ẩn menu desktop, hiện menu toggle */
    .nav-menu {
        display: none;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    /* Giảm kích thước font cho mobile */
    .hero h1 {
        font-size: 2.5rem;
    }

    /* Layout dọc cho search form */
    .search-form {
        flex-direction: column;
        align-items: center;
    }

    .search-input {
        min-width: auto;
        width: 100%;
    }

    /* Grid 1 cột cho features */
    .features-grid {
        grid-template-columns: 1fr;
    }
}