:root {
    --primary-color: #1e3a8a;
    --secondary-color: #3b82f6;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --border-color: #e5e7eb;
    --bg-color: #f9fafb;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
}

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

html {
    font-size: 16px;
    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-color: var(--bg-color);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 0 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 40px 0;
    text-align: center;
    box-shadow: var(--shadow);
    margin-bottom: 40px;
    position: relative;
}

.logo-section {
    animation: slideDown 0.6s ease-out;
}

.logo {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 10px;
    letter-spacing: -0.5px;
}

.tagline {
    font-size: 1.1rem;
    opacity: 0.95;
    font-weight: 300;
}

/* Language switcher dropdown */
.lang-switcher {
    z-index: 9999;
}
.lang-btn {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    padding: 7px 13px;
    background: rgba(0,0,0,0.35);
    color: #fff;
    border: 1.5px solid rgba(255,255,255,0.35);
    border-radius: 8px;
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
    letter-spacing: 0.2px;
    transition: background .15s;
}
.lang-btn:hover { background: rgba(0,0,0,0.5); }
.lang-arrow { font-size: 0.65rem; opacity: .8; margin-left: 2px; }
.lang-dropdown {
    display: none;
    position: absolute;
    top: calc(100% + 6px);
    right: 0;
    background: #1a1f2e;
    border-radius: 10px;
    overflow: hidden;
    min-width: 155px;
    box-shadow: 0 6px 24px rgba(0,0,0,0.55);
    border: 1px solid rgba(255,255,255,0.08);
}
.lang-switcher.open .lang-dropdown { display: block; }
.lang-option {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 16px;
    color: #d1d5db;
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 500;
    transition: background .12s;
}
.lang-option:hover { background: #2d3748; color: #fff; }
.lang-option.active {
    background: #2d3748;
    color: #f59e0b;
    font-weight: 700;
}
.lang-flag { font-size: 1.15rem; line-height: 1; }

/* Site navigation bar */
.site-nav {
    background: #0f172a;
    border-bottom: 1px solid rgba(255,255,255,0.08);
    display: flex;
    gap: 0;
    padding: 0 20px;
    margin-bottom: 32px;
}
.site-nav a {
    color: #9ca3af;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    padding: 13px 18px;
    border-bottom: 3px solid transparent;
    transition: color .15s, border-color .15s;
    letter-spacing: 0.2px;
}
.site-nav a:hover { color: #fff; }
.site-nav a.active {
    color: #f59e0b;
    border-bottom-color: #f59e0b;
}


    flex: 1;
    margin-bottom: 40px;
}

.form-section {
    margin-bottom: 40px;
}

.form-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.form-card h2 {
    font-size: 1.5rem;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.download-form {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    align-items: flex-end;
}

.form-group {
    flex: 1;
    min-width: 280px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-color);
    font-size: 0.95rem;
}

.form-input {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    font-family: inherit;
}

.form-input:focus {
    outline: none;
    border-color: var(--secondary-color);
    background-color: #f0f7ff;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-hint {
    display: block;
    margin-top: 5px;
    color: var(--text-light);
    font-size: 0.85rem;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    white-space: nowrap;
    text-decoration: none;
}

.btn-icon {
    font-size: 1.1rem;
}

.btn-primary {
    background-color: var(--secondary-color);
    color: white;
    box-shadow: var(--shadow);
}

.btn-primary:hover {
    background-color: #2563eb;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-success {
    background-color: var(--success-color);
    color: white;
    box-shadow: var(--shadow);
}

.btn-success:hover {
    background-color: #059669;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-large {
    padding: 14px 32px;
    font-size: 1.05rem;
    width: 100%;
}

.alert {
    padding: 15px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 12px;
    animation: slideDown 0.3s ease-out;
}

.alert-icon {
    font-size: 1.3rem;
    flex-shrink: 0;
}

.alert-error {
    background-color: #fee2e2;
    color: #991b1b;
    border-left: 4px solid var(--danger-color);
}

.alert-success {
    background-color: #d1fae5;
    color: #065f46;
    border-left: 4px solid var(--success-color);
}

.video-section {
    margin-bottom: 40px;
}

.video-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    animation: fadeIn 0.5s ease-out;
}

.video-card h2 {
    font-size: 1.5rem;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.video-thumbnail {
    margin-bottom: 20px;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow);
    background-color: var(--bg-color);
    max-height: 400px;
}

.video-thumbnail img {
    width: 100%;
    height: auto;
    display: block;
}

.video-details {
    margin-bottom: 20px;
}

.video-title {
    font-size: 1.3rem;
    margin-bottom: 15px;
    color: var(--text-color);
    word-break: break-word;
}

.video-meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-bottom: 15px;
}

.meta-item {
    padding: 12px;
    background-color: var(--bg-color);
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.meta-label {
    font-weight: 600;
    color: var(--text-color);
    margin-right: 8px;
}

.meta-value {
    color: var(--text-light);
}

.video-description {
    padding: 15px;
    background-color: var(--bg-color);
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
}

.video-description h4 {
    margin-bottom: 8px;
    color: var(--text-color);
}

.video-description p {
    color: var(--text-light);
    line-height: 1.6;
    word-break: break-word;
}

.download-form-action {
    margin-top: 20px;
}

.info-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.info-card {
    background: white;
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.info-card h3 {
    font-size: 1.2rem;
    margin-bottom: 15px;
    color: var(--primary-color);
}

.info-list {
    list-style-position: inside;
    color: var(--text-light);
    line-height: 1.8;
}

.info-list li {
    margin-bottom: 8px;
}

.footer {
    background-color: var(--text-color);
    color: white;
    text-align: center;
    padding: 30px 0;
    margin-top: auto;
    border-top: 1px solid var(--border-color);
}

.footer p {
    margin: 5px 0;
    font-size: 0.95rem;
}

.disclaimer {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.7);
    margin-top: 10px;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@media (max-width: 768px) {
    .logo {
        font-size: 2rem;
    }
    
    .download-form {
        flex-direction: column;
    }
    
    .form-group {
        width: 100%;
    }
    
    .btn-large {
        width: 100%;
    }
    
    .video-meta {
        grid-template-columns: 1fr;
    }
    
    .info-section {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .logo {
        font-size: 1.5rem;
    }
    
    .container {
        padding: 0 15px;
    }
}