:root {
    --bg: #f0f2f5;
    --card-bg: rgba(255, 255, 255, 0.7);
    --text: #1d1d1f;
}

body.dark-mode {
    --bg: #0b0b0c;
    --card-bg: rgba(30, 30, 30, 0.6);
    --text: #ffffff;
}

body {
    background-color: var(--bg);
    color: var(--text);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto;
    transition: 0.3s;
}

.glass-card {
    background: var(--card-bg);
    backdrop-filter: blur(20px); /* Тот самый эффект стекла */
    border-radius: 20px;
    padding: 20px;
    border: 1px solid rgba(255,255,255,0.1);
}

.content-container {
    padding: 40px;
    max-width: 900px;
    margin: 0 auto;
}

.topic-card {
    margin-bottom: 20px;
    transition: transform 0.3s ease;
}

.topic-card:hover {
    transform: scale(1.02); /* Легкое увеличение при наведении */
    background: rgba(255, 255, 255, 0.85); /* Чуть светлее при наведении */
}

.btn-open {
    display: inline-block;
    padding: 8px 16px;
    background: rgba(0, 122, 255, 0.8);
    color: white;
    border-radius: 10px;
    text-decoration: none;
    margin-top: 10px;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 25px;
}

.nav-section {
    flex: 1;
    display: flex;
    align-items: center;
}

.nav-center {
    justify-content: center;
    gap: 40px;
}

.nav-right {
    justify-content: flex-end;
    gap: 15px;
}

.nav-link {
    text-decoration: none;
    color: var(--text);
    transition: 0.2s;
}

.nav-link:hover {
    color: #007AFF;
}