* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #495057;
    background: linear-gradient(135deg, #f8f9fa 0%, white 100%);
    min-height: 100vh;
}
.navbar {
    position: fixed;
    z-index: 1000;
    top: 0;
    display: flex;
    align-items: center;
    width: 100%;
    height: 60px;
    padding: 0 2rem;
    border-bottom: 1px solid #dee2e6;
    background: rgba(255, 255, 255, .95);
    backdrop-filter: blur(10px);
}
.navbar-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
}
.navbar-logo {
    font-size: 1.5rem;
    font-weight: bold;
    text-decoration: none;
    color: #ff7f2a;
}
.navbar-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}
.navbar-menu a {
    font-weight: 500;
    position: relative;
    transition: color .3s ease;
    text-decoration: none;
    color: #6c757d;
}
.navbar-menu a:hover {
    color: #ff7f2a;
}
.navbar-menu a::after {
    position: absolute;
    bottom: -5px;
    left: 50%;
    width: 0;
    height: 2px;
    content: '';
    transition: all .3s ease;
    transform: translateX(-50%);
    background: #ff7f2a;
}
.navbar-menu a:hover::after {
    width: 100%;
}
.mobile-menu-btn {
    font-size: 1.5rem;
    display: none;
    padding: .5rem;
    cursor: pointer;
    color: #ff7f2a;
    border: none;
    background: none;
}
.mobile-menu-overlay {
    position: fixed;
    z-index: 1001;
    top: 0;
    left: 0;
    display: none;
    width: 100%;
    height: 100vh;
    background: rgba(0, 0, 0, .5);
}
.mobile-menu {
    position: fixed;
    z-index: 1002;
    top: 0;
    right: -300px;
    display: none;
    width: 300px;
    height: 100vh;
    transition: right .3s ease;
    background: white;
    box-shadow: -2px 0 10px rgba(0,0,0,.1);
}
.mobile-menu.active {
    right: 0;
}
.mobile-menu-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid #e9ecef;
}
.mobile-menu-header .logo {
    font-size: 1.2rem;
    font-weight: bold;
    color: #ff7f2a;
}
.mobile-menu-close {
    font-size: 1.5rem;
    cursor: pointer;
    color: #6c757d;
    border: none;
    background: none;
}
.mobile-menu-items {
    padding: 1rem 0;
    list-style: none;
}
.mobile-menu-items li {
    border-bottom: 1px solid #f8f9fa;
}
.mobile-menu-items a {
    font-weight: 500;
    display: block;
    padding: 1rem 1.5rem;
    transition: background-color .3s ease;
    text-decoration: none;
    color: #495057;
}
.mobile-menu-items a:hover {
    color: #ff7f2a;
    background-color: #f8f9fa;
}
.start-btn {
    border: 1px solid #ff7f2a;
    background-color: #ff7f2a;
    color: white;
    font-size: 15px;
    padding: 6px 12px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}
.start-btn:hover {
    background-color: #e56f1a;
    border-color: #e56f1a;
}
.container {
    max-width: 1100px;
    margin: 80px auto 40px;
    padding: 0 2rem;
}
.page-header {
    text-align: center;
    margin-bottom: 3rem;
}
.page-title {
    font-size: 2.2rem;
    font-weight: 600;
    color: #343a40;
    margin-bottom: 0.75rem;
}
.page-subtitle {
    font-size: 1.05rem;
    color: #6c757d;
}
.platform-selector {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 2.5rem;
    flex-wrap: wrap;
}
.platform-card {
    flex: 1;
    min-width: 280px;
    max-width: 400px;
    padding: 2rem;
    border: 1px solid #e9ecef;
    border-radius: 10px;
    background: white;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
}
.platform-card:hover {
    transform: translateY(-3px);
    border-color: #ff7f2a;
}
.platform-card.active {
    border-color: #ff7f2a;
    background: #fff5ed;
}
.platform-card.forum.active {
    border-color: #17a2b8;
    background: #e7f6f8;
}
.platform-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}
.platform-card.atena .platform-icon {
    color: #ff7f2a;
}
.platform-card.forum .platform-icon {
    color: #17a2b8;
}
.platform-name {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #343a40;
}
.platform-description {
    font-size: 0.9rem;
    color: #6c757d;
}
.content-selector {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}
.content-btn {
    padding: 0.6rem 1.5rem;
    border: 1px solid #e9ecef;
    border-radius: 8px;
    background: white;
    color: #6c757d;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}
.content-btn:hover {
    background: #f8f9fa;
    border-color: #ff7f2a;
    color: #ff7f2a;
}
.content-btn.active {
    border-color: #ff7f2a;
    color: #ff7f2a;
    background: #fff5ed;
}
.content-btn.active.forum-active {
    border-color: #17a2b8;
    color: #17a2b8;
    background: #e7f6f8;
}
.document-content {
    display: none;
    background: white;
    border-radius: 15px;
    padding: 2.5rem 3rem;
    border: 1px solid #e9ecef;
}
.document-content.active {
    display: block;
    animation: fadeIn 0.3s ease;
}
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}
.info-box {
    background: #f8f9fa;
    border-left: 3px solid #ff7f2a;
    padding: 1.25rem;
    margin-bottom: 1.5rem;
    border-radius: 8px;
}
.info-box.forum {
    border-left-color: #17a2b8;
}
.info-box h4 {
    font-size: 1.1rem;
    margin-bottom: 0.75rem;
    color: #343a40;
    font-weight: 600;
}
.info-box h4 i {
    color: #ff7f2a;
    margin-right: 0.5rem;
}
.info-box.forum h4 i {
    color: #17a2b8;
}
.info-box p {
    margin: 0.5rem 0;
    font-size: 0.95rem;
    line-height: 1.6;
}
.section {
    margin-bottom: 2rem;
}
.section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #343a40;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid #e9ecef;
}
.section h3 {
    font-size: 1.2rem;
    font-weight: 600;
    color: #495057;
    margin: 1.5rem 0 0.75rem;
}
.section ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}
.section li {
    margin-bottom: 0.5rem;
    line-height: 1.7;
    font-size: 0.95rem;
}
.section p {
    font-size: 0.95rem;
    line-height: 1.7;
    margin-bottom: 1rem;
}
.highlight-box {
    background: #fff3cd;
    border-left: 3px solid #ffc107;
    padding: 1rem;
    margin: 1.25rem 0;
    border-radius: 8px;
}
.highlight-box p {
    margin: 0;
    font-size: 0.9rem;
    line-height: 1.6;
}
.warning-box {
    background: #f8d7da;
    border-left: 3px solid #dc3545;
    padding: 1rem;
    margin: 1.25rem 0;
    border-radius: 8px;
}
.warning-box h4 {
    color: #721c24;
    margin-bottom: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
}
.warning-box p {
    margin: 0;
    font-size: 0.9rem;
    line-height: 1.6;
    color: #721c24;
}
.success-box {
    background: #d4edda;
    border-left: 3px solid #28a745;
    padding: 1rem;
    margin: 1.25rem 0;
    border-radius: 8px;
}
.success-box p {
    margin: 0;
    font-size: 0.9rem;
    line-height: 1.6;
    color: #155724;
}
.no-selection {
    text-align: center;
    padding: 4rem 2rem;
    color: #6c757d;
}
.no-selection i {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    opacity: 0.3;
}
.no-selection h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
}
.no-selection p {
    font-size: 0.95rem;
}
.footer {
    background: white;
    padding: 2rem;
    text-align: center;
    border-top: 1px solid #e9ecef;
    margin-top: 3rem;
}
.footer p {
    color: #6c757d;
    font-size: 0.9rem;
}
@media (max-width: 768px) {
    .navbar {
        padding: 0 1rem;
    }
    .navbar-menu {
        display: none;
    }
    .mobile-menu-btn,
    .mobile-menu,
    .mobile-menu-overlay {
        display: block;
    }
    .start-btn {
        margin-left: 20px;
        padding: 6px 20px;
        border-radius: 6px;
        font-weight: 600;
    }
    .container {
        padding: 0 1rem;
        margin-top: 100px;
    }
    .page-title {
        font-size: 1.8rem;
    }
    .page-subtitle {
        font-size: 0.95rem;
    }
    .platform-selector {
        flex-direction: column;
        gap: 1rem;
    }
    .platform-card {
        max-width: 100%;
    }
    .content-selector {
        flex-direction: column;
    }
    .content-btn {
        width: 100%;
    }
    .document-content {
        padding: 1.5rem;
    }
    .section h2 {
        font-size: 1.3rem;
    }
    .section h3 {
        font-size: 1.1rem;
    }
    .info-box,
    .highlight-box,
    .warning-box,
    .success-box {
        padding: 1rem;
    }
}
@media (max-width: 480px) {
    .page-title {
        font-size: 1.6rem;
    }
    .platform-icon {
        font-size: 2rem;
    }
    .platform-name {
        font-size: 1.1rem;
    }
    .document-content {
        padding: 1.25rem;
    }
    .section h2 {
        font-size: 1.2rem;
    }
    .section h3 {
        font-size: 1rem;
    }
}