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

body {
    font-family: 'Noto Sans', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
}

header {
    background-color: #55b;
    color: white;
    padding: 1rem 2rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header h1 {
    font-size: 1.8rem;
    font-weight: 600;
}

.lang-switcher {
    display: flex;
    gap: 0.5rem;
}

.lang-switcher a {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    transition: background-color 0.2s ease;
}

.lang-switcher a:hover {
    background-color: rgba(255, 255, 255, 0.2);
}

.lang-switcher a.active {
    background-color: rgba(255, 255, 255, 0.3);
    font-weight: 600;
}

.container {
    display: flex;
    min-height: calc(100vh - 70px);
}

.sidebar {
    width: 250px;
    background-color: #f5f5f5;
    border-right: 1px solid #ddd;
    padding: 1.5rem 1rem;
}

.sidebar h2 {
    font-size: 1.2rem;
    color: #55b;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid #55b;
}

.app-list {
    list-style: none;
}

.app-list li {
    margin-bottom: 0.5rem;
}

.app-list a {
    display: block;
    padding: 0.75rem 1rem;
    color: #333;
    text-decoration: none;
    border-radius: 4px;
    transition: all 0.2s ease;
    cursor: pointer;
}

.app-list a:hover {
    background-color: #e0e0e0;
    color: #55b;
}

.app-list a.active {
    background-color: #55b;
    color: white;
}

.main-content {
    flex: 1;
    padding: 2rem;
    max-width: 900px;
}

.app-details {
    display: none;
}

.app-details.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.app-details h2 {
    color: #55b;
    font-size: 2rem;
    margin-bottom: 1rem;
}

.app-details h3 {
    color: #333;
    font-size: 1.3rem;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.app-details p {
    margin-bottom: 1rem;
    line-height: 1.8;
    margin-left: 1.5rem;
}

.button {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background-color: #55b;
    color: white;
    text-decoration: none;
    border-radius: 4px;
    transition: background-color 0.2s ease;
    margin-right: 1rem;
    margin-top: 0.5rem;
    margin-left: 1.5rem;
}

.button:hover {
    background-color: #447;
}

.welcome {
    display: block;
}

.welcome h2 {
    color: #55b;
    font-size: 2rem;
    margin-bottom: 1rem;
}

.welcome p {
    line-height: 1.8;
    margin-bottom: 1rem;
    margin-left: 1.5rem;
}

footer {
    background-color: #f5f5f5;
    padding: 1.5rem 2rem;
    text-align: center;
    border-top: 1px solid #ddd;
    margin-top: 2rem;
}

@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        border-right: none;
        border-bottom: 1px solid #ddd;
    }
}