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

:root {
    --primary-color: #0088cc;
    --primary-dark: #0077b3;
    --secondary-color: #333;
    --text-color: #444;
    --text-light: #666;
    --bg-light: #f4f4f4;
    --bg-white: #ffffff;
    --border-color: #e0e0e0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background: var(--bg-white);
}

/* ============ Header & Navigation ============ */
header {
    background: rgba(255, 255, 255, 0.95);
    padding: 15px 50px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
}

.logo {
    font-size: 22px;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
    letter-spacing: -0.5px;
}

.logo::before {
    content: "🛡️";
    font-size: 28px;
}

nav {
    display: flex;
    align-items: center;
    gap: 40px;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 30px;
    margin: 0;
    padding: 0;
}

nav ul li a {
    text-decoration: none;
    color: var(--secondary-color);
    font-weight: 500;
    font-size: 15px;
    transition: color 0.3s ease;
    position: relative;
}

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

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

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

.lang-toggle {
    background: var(--bg-light);
    border: 1px solid var(--border-color);
    padding: 8px 15px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.lang-toggle:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* ============ Hero Section ============ */
.hero {
    background: linear-gradient(135deg, rgba(0, 0, 0, 0.65) 0%, rgba(0, 0, 0, 0.5) 100%),
                url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 600"><rect fill="%23222" width="1200" height="600"/><circle cx="200" cy="150" r="80" fill="%23333" opacity="0.5"/><circle cx="1000" cy="450" r="120" fill="%23333" opacity="0.3"/></svg>');
    background-size: cover;
    background-position: center;
    min-height: 550px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: var(--bg-white);
    text-align: center;
    padding: 60px 20px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(ellipse at 50% 50%, rgba(0, 136, 204, 0.1) 0%, transparent 70%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 900px;
}

.hero h1 {
    font-size: 52px;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.2;
    letter-spacing: -1px;
}

.hero p {
    font-size: 22px;
    margin-bottom: 35px;
    font-weight: 300;
    opacity: 0.95;
}

.hero-cta {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.btn-download {
    background: linear-gradient(135deg, var(--primary-color) 0%, #0066aa 100%);
    color: var(--bg-white);
    padding: 18px 50px;
    border-radius: 50px;
    text-decoration: none;
    font-size: 18px;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 10px 30px rgba(0, 136, 204, 0.3);
    border: 2px solid transparent;
    cursor: pointer;
    display: inline-block;
}

.btn-download:hover {
    background: linear-gradient(135deg, var(--primary-dark) 0%, #005599 100%);
    box-shadow: 0 15px 40px rgba(0, 136, 204, 0.4);
    transform: translateY(-2px);
}

.btn-download:active {
    transform: translateY(0);
}

.hero-subtitle {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.8);
    margin-top: 10px;
}

.hero-compat {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 14px;
    margin-top: 15px;
    color: rgba(255, 255, 255, 0.85);
}

.hero-compat::before {
    content: '🪟';
    font-size: 18px;
}

/* ============ Sections ============ */
.section {
    padding: 80px 50px;
    max-width: 1200px;
    margin: 0 auto;
}

.section h2 {
    text-align: center;
    font-size: 38px;
    font-weight: 700;
    margin-bottom: 50px;
    color: var(--secondary-color);
    position: relative;
}

.section h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: var(--primary-color);
    margin: 20px auto 0;
    border-radius: 2px;
}

/* ============ About Section ============ */
.about-section {
    background: var(--bg-white);
}

.about-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
    font-size: 16px;
    line-height: 1.8;
    color: var(--text-light);
}

/* ============ Features Section ============ */
.features-section {
    background: linear-gradient(135deg, #f8f9fa 0%, #f0f4f8 100%);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 40px;
    margin-top: 50px;
}

.feature-card {
    background: var(--bg-white);
    padding: 40px 30px;
    border-radius: 12px;
    text-align: center;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    border-top: 4px solid transparent;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 35px rgba(0, 0, 0, 0.15);
    border-top-color: var(--primary-color);
}

.feature-icon {
    font-size: 48px;
    margin-bottom: 20px;
    display: block;
}

.feature-card h4 {
    font-size: 20px;
    margin: 15px 0;
    color: var(--secondary-color);
    font-weight: 600;
}

.feature-card p {
    font-size: 15px;
    color: var(--text-light);
    line-height: 1.6;
}

/* ============ Use Cases Section ============ */
.use-cases-section {
    background: var(--bg-white);
}

.use-cases-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 50px;
    margin-top: 50px;
}

.use-case-card {
    padding: 40px;
    border-radius: 12px;
    background: linear-gradient(135deg, #f8f9fa 0%, #f0f4f8 100%);
    transition: all 0.3s ease;
    border-left: 5px solid var(--primary-color);
}

.use-case-card:hover {
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    transform: translateX(5px);
}

.use-case-card h3 {
    font-size: 22px;
    color: var(--secondary-color);
    margin-bottom: 15px;
    font-weight: 600;
}

.use-case-card p {
    font-size: 15px;
    color: var(--text-light);
    line-height: 1.7;
}

/* ============ CTA Section ============ */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, #0066aa 100%);
    color: var(--bg-white);
    text-align: center;
    padding: 80px 50px;
    margin: 60px 0 0 0;
}

.cta-section h2 {
    color: var(--bg-white);
    margin-bottom: 30px;
}

.cta-section h2::after {
    background: rgba(255, 255, 255, 0.3);
}

.cta-section p {
    font-size: 18px;
    margin-bottom: 30px;
    opacity: 0.95;
}

/* ============ Footer ============ */
footer {
    background: #1a1a1a;
    color: #999;
    padding: 50px;
    text-align: center;
}

footer p {
    margin: 0 0 20px 0;
    font-size: 14px;
}

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

.footer-links a {
    color: #999;
    text-decoration: none;
    font-size: 14px;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: var(--primary-color);
}

.footer-divider {
    color: #444;
    margin: 0 10px;
}

.lang-selector {
    margin-top: 25px;
    padding-top: 20px;
    border-top: 1px solid #333;
}

.lang-selector a {
    color: #999;
    text-decoration: none;
    margin: 0 10px;
    font-size: 14px;
    transition: color 0.3s ease;
}

.lang-selector a:hover {
    color: var(--primary-color);
}

/* ============ Language Modal ============ */
.modal-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    z-index: 2000;
    align-items: center;
    justify-content: center;
}

.modal-overlay.active {
    display: flex;
}

.modal-content {
    background: var(--bg-white);
    border-radius: 12px;
    padding: 40px;
    max-width: 600px;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-close {
    float: right;
    font-size: 28px;
    font-weight: bold;
    color: #999;
    cursor: pointer;
    border: none;
    background: none;
    transition: color 0.3s ease;
}

.modal-close:hover {
    color: var(--primary-color);
}

.modal-title {
    font-size: 24px;
    font-weight: 700;
    margin: 20px 0 30px 0;
    color: var(--secondary-color);
    clear: both;
}

.language-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
}

.lang-option {
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
}

.lang-option:hover {
    border-color: var(--primary-color);
    background: #f0f8ff;
    color: var(--primary-color);
}

/* ============ Responsive Design ============ */
@media (max-width: 768px) {
    header {
        padding: 12px 20px;
        flex-direction: column;
        gap: 15px;
    }

    nav {
        width: 100%;
        justify-content: center;
        gap: 20px;
    }

    nav ul {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }

    .hero {
        min-height: 400px;
        padding: 40px 20px;
    }

    .hero h1 {
        font-size: 32px;
    }

    .hero p {
        font-size: 18px;
    }

    .section {
        padding: 50px 20px;
    }

    .section h2 {
        font-size: 28px;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: 25px;
    }

    .use-cases-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .language-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .cta-section {
        padding: 50px 20px;
    }

    footer {
        padding: 30px 20px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 24px;
    }

    .hero p {
        font-size: 16px;
    }

    .btn-download {
        padding: 14px 35px;
        font-size: 16px;
    }

    .language-grid {
        grid-template-columns: 1fr;
    }

    nav ul li {
        margin: 0;
    }
}