:root {
    /* Базовая тёмная палитра */
    --bg-main: #080e15;
    --bg-card: rgba(15, 25, 38, 0.75);
    --bg-card-hover: rgba(22, 38, 58, 0.85);
    --bg-header: rgba(8, 14, 21, 0.92);
    --bg-interactive-box: rgba(0, 0, 0, 0.3);
    --bg-input: rgba(0, 0, 0, 0.4);
    --bg-track: rgba(255, 255, 255, 0.03);
    --bg-track-hover: rgba(255, 255, 255, 0.07);
    --bg-disclaimer: rgba(255, 255, 255, 0.03);
    --bg-secondary-btn: rgba(255, 255, 255, 0.05);
    --bg-secondary-btn-hover: rgba(255, 255, 255, 0.1);
    
    --accent-blue: #00f2fe;
    --accent-cyan: #4facfe;
    --accent-glow: rgba(0, 242, 254, 0.35);
    --accent-glow-hover: rgba(0, 242, 254, 0.5);
    --accent-btn-text: #000000;
    
    --text-primary: #f0f6fc;
    --text-secondary: #8b9eb0;
    --text-heading: #ffffff;
    --border-color: rgba(255, 255, 255, 0.1);

    --hero-radial-1: rgba(0, 242, 254, 0.15);
    --hero-radial-2: rgba(79, 172, 254, 0.12);

    --radius-lg: 16px;
    --radius-md: 10px;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

/* Светлая палитра */
[data-theme="light"] {
    --bg-main: #f4f7fb;
    --bg-card: rgba(255, 255, 255, 0.85);
    --bg-card-hover: rgba(255, 255, 255, 1);
    --bg-header: rgba(244, 247, 251, 0.94);
    --bg-interactive-box: rgba(235, 242, 250, 0.7);
    --bg-input: #ffffff;
    --bg-track: rgba(0, 0, 0, 0.03);
    --bg-track-hover: rgba(0, 0, 0, 0.06);
    --bg-disclaimer: rgba(0, 0, 0, 0.03);
    --bg-secondary-btn: rgba(0, 0, 0, 0.05);
    --bg-secondary-btn-hover: rgba(0, 0, 0, 0.09);

    --accent-blue: #0088cc;
    --accent-cyan: #00b4d8;
    --accent-glow: rgba(0, 136, 204, 0.25);
    --accent-glow-hover: rgba(0, 136, 204, 0.4);
    --accent-btn-text: #ffffff;

    --text-primary: #2c3e50;
    --text-secondary: #64748b;
    --text-heading: #0f172a;
    --border-color: rgba(0, 0, 0, 0.1);

    --hero-radial-1: rgba(0, 180, 216, 0.14);
    --hero-radial-2: rgba(0, 136, 204, 0.1);
}

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

html {
    scroll-behavior: smooth;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

body {
    overflow-x: hidden;
    background-color: var(--bg-main);
}

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

h1, h2, h3, h4 {
    color: var(--text-heading);
    line-height: 1.25;
    font-weight: 700;
}

a {
    color: inherit;
    text-decoration: none;
}

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 20px 0;
    transition: var(--transition);
}

.site-header.scrolled {
    background: var(--bg-header);
    backdrop-filter: blur(12px);
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

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

.header-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo {
    font-size: 1.6rem;
    font-weight: 800;
    letter-spacing: -0.5px;
    color: var(--text-heading);
}

.logo span {
    color: var(--accent-blue);
}

.main-nav ul {
    display: flex;
    list-style: none;
    gap: 25px;
    align-items: center;
}

.main-nav a {
    color: var(--text-secondary);
    font-size: 0.92rem;
    font-weight: 500;
    transition: var(--transition);
}

.main-nav a:hover {
    color: var(--accent-blue);
}

.nav-btn {
    padding: 8px 18px;
    border-radius: 50px;
    border: 1px solid var(--accent-blue);
    color: var(--accent-blue) !important;
}

.nav-btn:hover {
    background: var(--accent-blue);
    color: #fff !important;
}

/* Кнопка переключения темы */
.theme-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    border-radius: 50%;
    background: var(--bg-secondary-btn);
    border: 1px solid var(--border-color);
    color: var(--text-heading);
    cursor: pointer;
    transition: var(--transition);
}

.theme-toggle:hover {
    background: var(--bg-secondary-btn-hover);
    border-color: var(--accent-blue);
    transform: rotate(15deg);
}

/* Логика видимости иконок солнца и луны */
[data-theme="light"] .sun-icon {
    display: none;
}
[data-theme="light"] .moon-icon {
    display: block;
}

[data-theme="dark"] .sun-icon {
    display: block;
}
[data-theme="dark"] .moon-icon {
    display: none;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
}

.menu-toggle span {
    width: 25px;
    height: 2px;
    background-color: var(--text-heading);
    transition: var(--transition);
}

.hero {
    position: relative;
    padding: 180px 0 120px;
    min-height: 85vh;
    display: flex;
    align-items: center;
    background: radial-gradient(circle at 85% 15%, var(--hero-radial-1) 0%, transparent 45%),
                radial-gradient(circle at 15% 85%, var(--hero-radial-2) 0%, transparent 50%);
}

.badge {
    display: inline-block;
    padding: 6px 16px;
    background: rgba(0, 136, 204, 0.1);
    border: 1px solid var(--accent-blue);
    color: var(--accent-blue);
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 20px;
}

.hero-content {
    max-width: 820px;
}

.hero h1 {
    font-size: 3.2rem;
    margin-bottom: 20px;
    letter-spacing: -1px;
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 35px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-cyan));
    color: var(--accent-btn-text);
    box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 25px var(--accent-glow-hover);
}

.btn-secondary {
    background: var(--bg-secondary-btn);
    color: var(--text-heading);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-secondary-btn-hover);
    border-color: var(--accent-blue);
}

.btn-block {
    width: 100%;
}

.section {
    padding: 100px 0;
}

.section-title {
    margin-bottom: 60px;
}

.section-title h2 {
    font-size: 2.2rem;
    margin-bottom: 12px;
}

.section-title p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.text-center {
    text-align: center;
}

.grid {
    display: grid;
    gap: 25px;
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 30px;
    backdrop-filter: blur(10px);
    transition: var(--transition);
}

.card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-4px);
    border-color: var(--accent-blue);
}

.card-icon {
    width: 50px;
    height: 50px;
    border-radius: var(--radius-md);
    background: rgba(0, 136, 204, 0.1);
    color: var(--accent-blue);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

.card h3 {
    font-size: 1.25rem;
    margin-bottom: 12px;
}

.card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.concept-box {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 25px;
    transition: var(--transition);
}

.concept-box:hover {
    border-color: var(--accent-blue);
}

.concept-tag {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--accent-blue);
    font-weight: 700;
}

.concept-box h3 {
    margin: 8px 0 12px;
    font-size: 1.2rem;
}

.concept-box p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.interactive-tunnel {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 30px;
}

.tunnel-visual {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.lane-track {
    display: flex;
    align-items: center;
    padding: 14px 18px;
    background: var(--bg-track);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
}

.lane-track:hover {
    background: var(--bg-track-hover);
}

.lane-track.active {
    background: linear-gradient(90deg, rgba(0, 136, 204, 0.15), transparent);
    border-color: var(--accent-blue);
}

.lane-num {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--bg-secondary-btn-hover);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    margin-right: 15px;
    color: var(--text-heading);
}

.lane-track.active .lane-num {
    background: var(--accent-blue);
    color: #fff;
}

.lane-title {
    font-weight: 600;
    flex-grow: 1;
}

.lane-speed-tag {
    font-size: 0.85rem;
    padding: 4px 10px;
    background: var(--bg-secondary-btn);
    border-radius: 20px;
    color: var(--text-secondary);
}

.tunnel-info-box {
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 25px;
    background: var(--bg-interactive-box);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.info-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.speed-badge {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent-blue);
}

.lane-features {
    display: flex;
    gap: 10px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.feature-tag {
    font-size: 0.8rem;
    padding: 4px 12px;
    border-radius: 4px;
    background: rgba(0, 136, 204, 0.12);
    color: var(--accent-blue);
    font-weight: 500;
}

.video-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition);
}

.video-card:hover {
    border-color: var(--accent-blue);
    transform: translateY(-4px);
}

.video-wrapper iframe {
    width: 100%;
    height: 100%;
    border: none;
    aspect-ratio: 16 / 9;
}

.video-wrapper video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-card-body {
    padding: 20px;
}

.video-card-body h3 {
    font-size: 1.1rem;
    margin-bottom: 8px;
}

.video-card-body p {
    color: var(--text-secondary);
    font-size: 0.88rem;
}

.benefit-item {
    display: flex;
    gap: 20px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 30px;
    transition: var(--transition);
}

.benefit-item:hover {
    border-color: var(--accent-blue);
}

.benefit-number {
    font-size: 2rem;
    font-weight: 800;
    color: var(--accent-blue);
}

.benefit-item h3 {
    margin-bottom: 8px;
}

.benefit-item p {
    color: var(--text-secondary);
}

.disclaimer-banner {
    margin-top: 40px;
    padding: 20px 30px;
    background: var(--bg-disclaimer);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.88rem;
}

.contact-details {
    display: grid;
    gap: 18px;
    margin-top: 30px;
}

.contact-detail-item {
    display: flex;
    flex-direction: column;
}

.detail-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.detail-value {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-heading);
}

.detail-value.link {
    color: var(--accent-blue);
}

.contact-form-wrapper {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 35px;
}

.contact-form h3 {
    margin-bottom: 20px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 0.9rem;
    margin-bottom: 8px;
    color: var(--text-secondary);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-heading);
    font-family: inherit;
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-blue);
}

.form-status {
    margin-top: 15px;
    font-size: 0.9rem;
    text-align: center;
}

.form-status.success { color: #00c853; }

.site-footer {
    padding: 30px 0;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.fade-element {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-element.visible {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 992px) {
    .grid-4, .grid-3 { grid-template-columns: repeat(2, 1fr); }
    .interactive-tunnel { grid-template-columns: 1fr; }
    .hero h1 { font-size: 2.5rem; }
}

@media (max-width: 768px) {
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
    
    .menu-toggle { display: flex; }

    .main-nav {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        background: var(--bg-main);
        padding: 80px 30px;
        transition: var(--transition);
        border-left: 1px solid var(--border-color);
        box-shadow: -10px 0 30px rgba(0, 0, 0, 0.2);
    }

    .main-nav.active { right: 0; }

    .main-nav ul {
        flex-direction: column;
        align-items: flex-start;
        gap: 20px;
    }

    .footer-content {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }
}

/* Блок мессенджеров */
.messengers-block {
    margin-top: 25px;
}

.social-buttons {
    display: flex;
    gap: 12px;
    margin-top: 10px;
    flex-wrap: wrap;
}

.social-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 600;
    text-decoration: none;
    background: var(--bg-secondary-btn);
    border: 1px solid var(--border-color);
    color: var(--text-heading);
    transition: var(--transition);
}

.social-btn svg {
    flex-shrink: 0;
}

/* Telegram */
.social-btn.tg-btn:hover {
    background: #229ED9;
    border-color: #229ED9;
    color: #fff;
    box-shadow: 0 4px 14px rgba(34, 158, 217, 0.4);
    transform: translateY(-2px);
}

/* WhatsApp */
.social-btn.wa-btn:hover {
    background: #25D366;
    border-color: #25D366;
    color: #fff;
    box-shadow: 0 4px 14px rgba(37, 211, 102, 0.4);
    transform: translateY(-2px);
}

/* Мессенджер MAX */
.social-btn.max-btn:hover {
    background: linear-gradient(135deg, #6c5ce7, #a29bfe);
    border-color: #6c5ce7;
    color: #fff;
    box-shadow: 0 4px 14px rgba(108, 92, 231, 0.4);
    transform: translateY(-2px);
}

/* Статусы формы */
.form-status {
    margin-top: 15px;
    font-size: 0.92rem;
    text-align: center;
    min-height: 24px;
    transition: var(--transition);
}

.form-status.success {
    color: #00c853;
}

.form-status.error {
    color: #ff5252;
}

.form-status.loading {
    color: var(--accent-blue);
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
}