/* --- 全局样式 --- */
:root {
    --primary-color: #FF7428; /* 一个活泼的红色，契合“爆品”和“团购”的热烈氛围 */
    --secondary-color: #4ECDC4; /* 一个清新的青色，带来健康和活力的感觉 */
    --dark-color: #333;
    --light-color: #f4f4f4;
    --text-color: #555;
    --navbar-height: 70px;
}

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

body {
    font-family: 'Helvetica Neue', Arial, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    background: #fff;
    color: var(--text-color);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 20px;
}

a {
    text-decoration: none;
    color: var(--primary-color);
}

ul {
    list-style: none;
}

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

/* --- 导航栏 --- */
.navbar {
    background: #fff;
    color: var(--dark-color);
    height: var(--navbar-height);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    transition: background 0.3s ease;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.navbar .logo {
    display: flex;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
    color: var(--dark-color);
}

.navbar .logo img {
    height: 40px;
    margin-right: 10px;
}

.navbar .nav-links {
    display: flex;
}

.navbar .nav-links li {
    margin-left: 20px;
}

.navbar .nav-links a {
    color: var(--dark-color);
    padding: 5px 10px;
    transition: color 0.3s ease, border-bottom 0.3s ease;
    border-bottom: 2px solid transparent;
}

.navbar .nav-links a:hover,
.navbar .nav-links a.active {
    color: var(--primary-color);
    border-bottom: 2px solid var(--primary-color);
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
}

.hamburger {
    display: block;
    width: 25px;
    height: 3px;
    background: var(--dark-color);
    position: relative;
    transition: background 0.3s ease;
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    width: 25px;
    height: 3px;
    background: var(--dark-color);
    left: 0;
    transition: transform 0.3s ease, top 0.3s ease;
}

.hamburger::before {
    top: -8px;
}

.hamburger::after {
    top: 8px;
}


/* --- Hero Section --- */
.hero-section {
    background: linear-gradient(#FF7428, rgba(0, 0, 0, 0.5)), url('../images/hero-bg.jpg') no-repeat center center/cover;
    color: #fff;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding-top: var(--navbar-height);
}

.hero-section h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
}

.hero-section p {
    font-size: 1.5rem;
    margin-bottom: 2rem;
}

.btn {
    display: inline-block;
    padding: 12px 25px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s ease, transform 0.3s ease;
}

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

.btn-primary:hover {
    background: #e05a5a;
    transform: translateY(-2px);
}

/* --- Sections --- */
section {
    padding: 60px 0;
}

section h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 40px;
    color: var(--dark-color);
}

/* --- About Section --- */
.about-section .container p {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    font-size: 1.1rem;
}

/* --- Features Section --- */
.features-section {
    background: var(--light-color);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    text-align: center;
}

.feature-item img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: 10px;
    margin-bottom: 20px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.feature-item h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: var(--dark-color);
}

/* --- Download Section --- */
.download-section {
    text-align: center;
}

.download-section p {
    margin-bottom: 30px;
}

.download-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-bottom: 30px;
}

.download-btn {
    display: flex;
    align-items: center;
    padding: 15px 30px;
    border-radius: 8px;
    color: #fff;
    font-size: 1.2rem;
    font-weight: bold;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.download-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.download-btn.ios { background-color: #000; }
.download-btn.android { background-color: #3DDC84; }
.download-btn.harmony { background-color: #DE343A; }

.download-btn i {
    margin-right: 10px;
    font-size: 1.5rem; /* Placeholder for icon */
}

.qr-code img {
    width: 150px;
    height: 150px;
    margin: 0 auto;
    display: block;
}

.qr-code p {
    margin-top: 10px;
    font-size: 0.9rem;
}

/* --- Follow Us Section --- */
.follow-section {
    background: var(--light-color);
    text-align: center;
}

.follow-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    max-width: 900px;
    margin: 0 auto;
}

.follow-item {
    background: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.follow-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 15px rgba(0,0,0,0.1);
}

.follow-item img {
    width: 150px;
    height: 150px;
    margin: 0 auto 15px;
}

.follow-item h3 {
    font-size: 1.2rem;
    margin-bottom: 5px;
    color: var(--dark-color);
}

.follow-item p {
    font-size: 0.9rem;
    color: #777;
}


/* --- Footer --- */
.footer {
    background: var(--dark-color);
    color: #ccc;
    text-align: center;
    padding: 30px 0;
}

.footer .footer-links {
    margin-bottom: 15px;
}

.footer .footer-links a {
    color: #ccc;
    margin: 0 10px;
    transition: color 0.3s ease;
}

.footer .footer-links a:hover {
    color: #fff;
}

.footer p {
    margin: 8px 0;
    font-size: 0.9rem;
}

.footer p a {
    color: #ccc;
    text-decoration: underline;
}

.footer p a:hover {
    color: #fff;
}


/* --- 响应式设计 --- */
@media (max-width: 768px) {
    .navbar .container {
        padding: 0 20px;
    }

    .navbar .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: var(--navbar-height);
        left: 0;
        width: 100%;
        background: #fff;
        padding: 20px 0;
        box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    }

    .navbar .nav-links.active {
        display: flex;
    }

    .navbar .nav-links li {
        margin: 10px 0;
        text-align: center;
    }

    .menu-toggle {
        display: block;
    }
    
    .menu-toggle.active .hamburger {
        background: transparent;
    }

    .menu-toggle.active .hamburger::before {
        transform: rotate(45deg);
        top: 0;
    }

    .menu-toggle.active .hamburger::after {
        transform: rotate(-45deg);
        top: 0;
    }

    .hero-section h1 {
        font-size: 2.5rem;
    }

    .hero-section p {
        font-size: 1.2rem;
    }

    .features-grid,
    .follow-grid {
        grid-template-columns: 1fr;
    }
}