:root {
    --bg-primary: #0a0e1a;
    --bg-secondary: #141b2d;
    --bg-tertiary: #1e2742;
    --bg-card: #1a2332;
    --text-primary: #e0e6ed;
    --text-secondary: #a8b3c1;
    --accent-primary: #00d4ff;
    --accent-secondary: #0099cc;
    --accent-tertiary: #006699;
    --border-color: #2a3441;
    --success: #00ff88;
    --warning: #ffaa00;
    --error: #ff4444;
    --sidebar-width: 320px;
    --header-height: 60px;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Шапка */
.app-header {
    height: var(--header-height);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
    height: 100%;
}

.logo {
    font-size: 1.5rem;
    color: var(--accent-primary);
    font-weight: 600;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.user-progress {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.progress-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.progress-bar {
    width: 200px;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--accent-primary);
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.9rem;
    color: var(--accent-primary);
    font-weight: 500;
    min-width: 40px;
}

/* Основной layout */
.main-layout {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* Боковая панель */
.sidebar {
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    transition: transform 0.3s ease;
}

.sidebar-content {
    padding: 1.5rem;
}

.search-box {
    position: relative;
    margin-bottom: 1.5rem;
}

.search-input {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.search-input:focus {
    outline: none;
    border-color: var(--accent-primary);
}

.search-results {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    max-height: 300px;
    overflow-y: auto;
    z-index: 100;
    margin-top: 0.5rem;
    display: none;
}

.search-results.active {
    display: block;
}

.search-result-item {
    padding: 0.75rem;
    cursor: pointer;
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s;
}

.search-result-item:hover {
    background: var(--bg-tertiary);
}

/* Навигация */
.main-nav {
    margin-bottom: 1.5rem;
}

.nav-section {
    margin-bottom: 1rem;
}

.nav-section-title {
    color: var(--accent-primary);
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
    padding: 0.5rem 0;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-section-title::after {
    content: '▼';
    font-size: 0.7rem;
    transition: transform 0.3s;
}

.nav-section-title.collapsed::after {
    transform: rotate(-90deg);
}

.nav-section-items {
    list-style: none;
    margin-left: 1rem;
}

.nav-section-items.collapsed {
    display: none;
}

.nav-item {
    margin-bottom: 0.25rem;
}

.nav-link {
    display: block;
    padding: 0.5rem 0.75rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: 4px;
    transition: all 0.2s;
    font-size: 0.9rem;
}

.nav-link:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.nav-link.active {
    background: var(--bg-tertiary);
    color: var(--accent-primary);
    border-left: 3px solid var(--accent-primary);
    padding-left: calc(0.75rem - 3px);
}

/* Селектор уровня */
.level-selector {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.level-selector label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.level-select {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
}

.level-select:focus {
    outline: none;
    border-color: var(--accent-primary);
}

/* Основной контент */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.content-header {
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-secondary);
}

.breadcrumbs {
    display: flex;
    gap: 0.5rem;
    align-items: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.breadcrumb-item {
    color: var(--text-secondary);
    text-decoration: none;
}

.breadcrumb-item:hover {
    color: var(--accent-primary);
}

.breadcrumb-separator {
    color: var(--text-secondary);
}

.content-actions {
    display: flex;
    gap: 0.5rem;
}

.content-wrapper {
    flex: 1;
    overflow-y: auto;
    padding: 2rem;
}

/* Приветственный экран */
.welcome-screen {
    text-align: center;
    padding: 4rem 2rem;
}

.welcome-screen h1 {
    font-size: 2.5rem;
    color: var(--accent-primary);
    margin-bottom: 1rem;
}

.subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

.welcome-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    max-width: 800px;
    margin: 0 auto;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
}

.stat-number {
    font-size: 3rem;
    color: var(--accent-primary);
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Урок */
.lesson-container {
    max-width: 1000px;
    margin: 0 auto;
}

.lesson-header {
    margin-bottom: 2rem;
}

.lesson-title {
    font-size: 2rem;
    color: var(--accent-primary);
    margin-bottom: 0.5rem;
}

.lesson-meta {
    display: flex;
    gap: 1.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.lesson-level-badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--accent-primary);
    color: var(--bg-primary);
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* Блоки контента */
.content-block {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 2rem;
}

.content-block-title {
    color: var(--accent-primary);
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

/* Табы уровней */
.level-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 2rem;
    border-bottom: 2px solid var(--border-color);
}

.level-tab {
    padding: 0.75rem 1.5rem;
    background: transparent;
    border: none;
    border-bottom: 3px solid transparent;
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s;
}

.level-tab:hover {
    color: var(--text-primary);
}

.level-tab.active {
    color: var(--accent-primary);
    border-bottom-color: var(--accent-primary);
}

.level-content {
    display: none;
}

.level-content.active {
    display: block;
}

/* Пустое состояние */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
}

.empty-state-title {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.empty-state-text {
    margin-bottom: 2rem;
}

.generate-btn {
    padding: 1rem 2rem;
    background: var(--accent-primary);
    color: var(--bg-primary);
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
}

.generate-btn:hover {
    background: var(--accent-secondary);
    transform: translateY(-2px);
}

/* Кнопки */
.btn-icon {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 0.5rem 1rem;
    cursor: pointer;
    color: var(--text-primary);
    font-size: 1.2rem;
    transition: all 0.3s;
}

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

/* Модальные окна */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10000;
}

.modal-overlay.hidden {
    display: none;
}

.modal-content {
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 2rem;
    max-width: 800px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    width: 90%;
}

.modal-close {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 2rem;
    cursor: pointer;
    width: 2rem;
    height: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-close:hover {
    color: var(--accent-primary);
}

/* Адаптивность */


    .sidebar.open {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
    }

    .content-wrapper {
        padding: 1rem;
    }
}

/* Утилиты */
.hidden {
    display: none !important;
}

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

.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }

/* Интерактивные элементы */
.quiz {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    margin: 2rem 0;
}

.quiz-question {
    margin-bottom: 1.5rem;
}

.quiz-options {
    list-style: none;
    margin: 0;
    padding: 0;
}

.quiz-option {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 1rem;
    margin-bottom: 0.75rem;
    cursor: pointer;
    transition: all 0.3s;
}

.quiz-option:hover {
    border-color: var(--accent-primary);
    background: var(--bg-secondary);
}

.quiz-option.correct {
    border-color: var(--success);
    background: rgba(0, 255, 136, 0.1);
}

.quiz-option.incorrect {
    border-color: var(--error);
    background: rgba(255, 68, 68, 0.1);
}

.quiz-option.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Пошаговые инструкции */
.step-by-step {
    background: var(--bg-secondary);
    border-left: 4px solid var(--accent-primary);
    padding: 1.5rem;
    margin: 1.5rem 0;
    border-radius: 6px;
}

.step {
    display: flex;
    align-items: flex-start;
    margin-bottom: 1.5rem;
    padding: 1rem;
    background: var(--bg-tertiary);
    border-radius: 6px;
}

.step:last-child {
    margin-bottom: 0;
}

.step-number {
    background: var(--accent-primary);
    color: var(--bg-primary);
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 1.2rem;
    flex-shrink: 0;
    margin-right: 1rem;
}

.step-content {
    flex: 1;
}

/* Схемы */
.diagram {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 2rem;
    margin: 1.5rem 0;
    text-align: center;
    overflow-x: auto;
}

.diagram svg {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
}

/* Блоки с советами */
.tip {
    background: rgba(0, 212, 255, 0.1);
    border-left: 4px solid var(--accent-primary);
    padding: 1rem 1.5rem;
    margin: 1.5rem 0;
    border-radius: 4px;
}

.tip-title {
    color: var(--accent-primary);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.warning {
    background: rgba(255, 170, 0, 0.1);
    border-left: 4px solid var(--warning);
    padding: 1rem 1.5rem;
    margin: 1.5rem 0;
    border-radius: 4px;
}

.warning-title {
    color: var(--warning);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.error-block {
    background: rgba(255, 68, 68, 0.1);
    border-left: 4px solid var(--error);
    padding: 1rem 1.5rem;
    margin: 1.5rem 0;
    border-radius: 4px;
}

.error-title {
    color: var(--error);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

/* Таблицы */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    background: var(--bg-tertiary);
    border-radius: 6px;
    overflow: hidden;
}

th, td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background: var(--bg-secondary);
    color: var(--accent-primary);
    font-weight: 600;
}

td {
    color: var(--text-secondary);
}

tr:hover {
    background: var(--bg-secondary);
}

/* Симуляции */
.simulation {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    margin: 2rem 0;
}

.simulation-canvas {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 2rem;
    min-height: 400px;
    margin: 1.5rem 0;
}

/* Калькуляторы */
.calculator {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    margin: 2rem 0;
}

.calculator-title {
    color: var(--accent-primary);
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
}

.calculator-input-group {
    margin-bottom: 1.5rem;
}

.calculator-input-group label {
    display: block;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.calculator-input-group input,
.calculator-input-group select {
    width: 100%;
    padding: 0.75rem;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 1rem;
}

.calculator-result {
    background: var(--bg-tertiary);
    border: 2px solid var(--accent-primary);
    border-radius: 6px;
    padding: 1.5rem;
    margin-top: 1.5rem;
    text-align: center;
}

.calculator-result-value {
    font-size: 2rem;
    color: var(--accent-primary);
    font-weight: bold;
    margin: 0.5rem 0;
}

/* Скроллбар */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-tertiary);
}


/* ========== МОБИЛЬНАЯ ОПТИМИЗАЦИЯ ========== */
    .app-container {
        flex-direction: column;

    
    .sidebar {
        position: fixed;
        left: -100%;
        top: 0;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        z-index: 1000;
        transition: left 0.3s ease;
        box-shadow: 2px 0 10px rgba(0, 0, 0, 0.3);
    }
    
    .sidebar.active {
        left: 0;
    }
    
    .main-content {
        width: 100%;
        margin-left: 0;
        padding: 1rem;
    }
    
    .app-header {
        padding: 0.75rem 1rem;
    }
    
    .logo {
        font-size: 1.2rem;
    }
    
    .header-right {
        gap: 0.5rem;
    }
    
    .user-progress {
        display: none; /* Скрываем прогресс на мобильных */
    }
    
    .content-block {
        padding: 1rem;
        margin: 1rem 0;
    }
    
    .content-block-title {
        font-size: 1.5rem;
    }
    
    h2, h3, h4 {
        font-size: 1.3rem;
    }
    
    h3 {
        font-size: 1.1rem;
    }
    
    h4 {
        font-size: 1rem;
    }
    
    table {
        font-size: 0.85rem;
        display: block;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    table thead,
    table tbody,
    table tr,
    table td,
    table th {
        display: block;
    }
    
    table thead {
        display: none;
    }
    
    table tr {
        margin-bottom: 1rem;
        border: 1px solid rgba(168, 179, 193, 0.3);
        border-radius: 8px;
        padding: 0.5rem;
        background: rgba(30, 39, 66, 0.3);
    }
    
    table td {
        border: none;
        padding: 0.5rem;
        text-align: left;
        position: relative;
        padding-left: 50%;
    }
    
    table td::before {
        content: attr(data-label);
        position: absolute;
        left: 0.5rem;
        width: 45%;
        font-weight: bold;
        color: #00d4ff;
    }
    
    .step-by-step {
        padding: 0.5rem;
    }
    
    .step {
        margin: 1rem 0;
        padding: 0.75rem;
    }
    
    .step-number {
        width: 35px;
        height: 35px;
        font-size: 1rem;
    }
    
    .diagram svg {
        width: 100%;
        height: auto;
        max-width: 100%;
    }
    
    .quiz {
        padding: 1rem;
    }
    
    .quiz-option {
        padding: 0.75rem;
        font-size: 0.9rem;
    }
    
    .search-results {
        width: 100%;
        max-width: 100%;
        left: 0;
        right: 0;
    }
    
    .breadcrumbs {
        font-size: 0.85rem;
        flex-wrap: wrap;
    }
}


    
    .logo {
        font-size: 1rem;
    }
    
    .content-block {
        padding: 0.75rem;
    }
    
    .content-block-title {
        font-size: 1.3rem;
    }
    
    h2 {
        font-size: 1.2rem;
    }
    
    h3 {
        font-size: 1rem;
    }
    
    h4 {
        font-size: 0.9rem;
    }
    
    p {
        font-size: 0.9rem;
        line-height: 1.6;
    }
    
    .step-number {
        width: 30px;
        height: 30px;
        font-size: 0.9rem;
    }
    
    .step-content {
        padding: 0.5rem;
    }
}

/* Улучшенная адаптивность для планшетов */

    
    .main-content {
        margin-left: 250px;
        padding: 1.5rem;
    }
    
    .content-block {
        padding: 1.25rem;
    }
}

/* Улучшенная адаптивность для больших экранов */
@media (min-width: 1920px) {
    .app-container {
        max-width: 1800px;
        margin: 0 auto;
    }
    
    .main-content {
        padding: 2rem;
    }
}


.nav-lessons {
    list-style: none;
    margin-left: 1rem;
    padding: 0;
}

.nav-link {
    display: block;
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: 4px;
    transition: background 0.2s;
}

.nav-link:hover {
    background: var(--bg-secondary);
    color: var(--accent-primary);
}

.nav-link.active {
    background: var(--bg-tertiary);
    color: var(--accent-primary);
    font-weight: 600;
}

.nav-section-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem;
    cursor: pointer;
    border-radius: 4px;
    transition: background 0.2s;
}

.nav-section-header:hover {
    background: var(--bg-secondary);
}


/* ========== УЛУЧШЕНИЯ ДЛЯ ЧТЕНИЯ ========== */

/* Улучшенная типографика */
body {
    line-height: 1.8 !important;
    letter-spacing: 0.02em;
}

/* Улучшенные заголовки */
h1, h2, h3, h4 {
    line-height: 1.4 !important;
    margin-top: 2rem !important;
    margin-bottom: 1rem !important;
}

h1 {
    font-size: 2.5rem !important;
    font-weight: 700 !important;
    letter-spacing: -0.02em;
}

h2 {
    font-size: 2rem !important;
    font-weight: 600 !important;
    margin-top: 2.5rem !important;
}

h3 {
    font-size: 1.5rem !important;
    font-weight: 600 !important;
    margin-top: 2rem !important;
}

h4 {
    font-size: 1.25rem !important;
    font-weight: 500 !important;
    margin-top: 1.5rem !important;
}

/* Улучшенные параграфы */
p {
    line-height: 1.9 !important;
    margin-bottom: 1.5rem !important;
    color: #d4d9e0 !important;
    font-size: 1.05rem !important;
}

/* Улучшенные списки */
ul, ol {
    line-height: 1.9 !important;
    margin-bottom: 1.5rem !important;
    padding-left: 2rem !important;
}

li {
    margin-bottom: 0.75rem !important;
    line-height: 1.8 !important;
    color: #d4d9e0 !important;
}

/* Улучшенные блоки контента */
.content-block {
    background: rgba(30, 39, 66, 0.4) !important;
    border-radius: 12px !important;
    padding: 2rem !important;
    margin: 2rem 0 !important;
    border: 1px solid rgba(0, 212, 255, 0.1) !important;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2) !important;
}

/* Улучшенные цветные блоки для заголовков */
.content-block h2,
.content-block h3 {
    background: linear-gradient(135deg, rgba(0, 123, 255, 0.2) 0%, rgba(0, 86, 179, 0.2) 100%) !important;
    border-left: 4px solid #007BFF !important;
    padding: 1.25rem 1.5rem !important;
    margin: 2rem 0 1.5rem 0 !important;
    border-radius: 8px !important;
    box-shadow: 0 2px 8px rgba(0, 123, 255, 0.15) !important;
}

/* Улучшенные таблицы */
table {
    background: rgba(30, 39, 66, 0.6) !important;
    border-radius: 12px !important;
    overflow: hidden !important;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3) !important;
    margin: 2rem 0 !important;
}

table th {
    background: linear-gradient(135deg, rgba(0, 212, 255, 0.25) 0%, rgba(0, 172, 193, 0.25) 100%) !important;
    padding: 1.25rem !important;
    font-weight: 600 !important;
    font-size: 1.05rem !important;
}

table td {
    padding: 1rem 1.25rem !important;
    border-bottom: 1px solid rgba(168, 179, 193, 0.15) !important;
    line-height: 1.7 !important;
}

table tr:hover {
    background: rgba(0, 123, 255, 0.1) !important;
    transition: background 0.2s ease !important;
}

/* Улучшенные step-by-step инструкции */
.step-by-step {
    margin: 2rem 0 !important;
}

.step {
    background: rgba(0, 123, 255, 0.08) !important;
    border-left: 4px solid #007BFF !important;
    border-radius: 8px !important;
    padding: 1.5rem !important;
    margin: 1.5rem 0 !important;
    box-shadow: 0 2px 8px rgba(0, 123, 255, 0.1) !important;
    transition: transform 0.2s ease, box-shadow 0.2s ease !important;
}

.step:hover {
    transform: translateX(4px) !important;
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.2) !important;
}

.step-number {
    background: linear-gradient(135deg, #007BFF 0%, #0056b3 100%) !important;
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.3) !important;
    width: 45px !important;
    height: 45px !important;
    font-size: 1.3rem !important;
}

.step-content {
    background: rgba(0, 123, 255, 0.05) !important;
    padding: 1.25rem !important;
    border-radius: 8px !important;
    line-height: 1.8 !important;
}

.step-content strong {
    color: #00d4ff !important;
    font-size: 1.1rem !important;
    display: block !important;
    margin-bottom: 0.75rem !important;
}

.step-content p {
    margin-bottom: 0.5rem !important;
    color: #d4d9e0 !important;
}

/* Улучшенные блоки с информацией */
div[style*="background: linear-gradient"] {
    border-radius: 10px !important;
    padding: 1.5rem !important;
    margin: 2rem 0 !important;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2) !important;
}

/* Улучшенные ссылки */
a {
    color: #00d4ff !important;
    text-decoration: none !important;
    transition: color 0.2s ease !important;
    border-bottom: 1px solid transparent !important;
}

a:hover {
    color: #00b8e6 !important;
    border-bottom-color: #00b8e6 !important;
}

/* Улучшенные блоки кода */
code, pre {
    background: rgba(0, 0, 0, 0.4) !important;
    border-radius: 6px !important;
    padding: 0.5rem 0.75rem !important;
    font-family: 'Courier New', monospace !important;
    font-size: 0.95rem !important;
    border: 1px solid rgba(0, 212, 255, 0.2) !important;
}

/* Улучшенные разделители */
hr {
    border: none !important;
    height: 2px !important;
    background: linear-gradient(90deg, transparent, rgba(0, 212, 255, 0.3), transparent) !important;
    margin: 3rem 0 !important;
}

/* Улучшенные блоки с предупреждениями/советами */
.alert, .warning, .info {
    border-radius: 10px !important;
    padding: 1.5rem !important;
    margin: 2rem 0 !important;
    border-left: 4px solid !important;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2) !important;
    line-height: 1.8 !important;
}

/* Улучшенные отступы для контента */
#contentWrapper {
    max-width: 1200px !important;
    margin: 0 auto !important;
    padding: 2rem !important;
}

.lesson-title {
    font-size: 2.5rem !important;
    margin-bottom: 2rem !important;
    padding-bottom: 1rem !important;
    border-bottom: 3px solid #00d4ff !important;
}

/* Улучшенная читаемость для мобильных */

    
    h1 {
        font-size: 2rem !important;
    }
    
    h2 {
        font-size: 1.75rem !important;
    }
    
    h3 {
        font-size: 1.5rem !important;
    }
    
    .content-block {
        padding: 1.5rem !important;
    }
}


/* ========== УЛУЧШЕННАЯ НАВИГАЦИЯ ========== */

.nav-section {
    background: rgba(30, 39, 66, 0.3) !important;
    border-radius: 8px !important;
    padding: 0.75rem !important;
    margin-bottom: 1rem !important;
    border: 1px solid rgba(0, 212, 255, 0.1) !important;
    transition: all 0.2s ease !important;
}

.nav-section:hover {
    background: rgba(30, 39, 66, 0.5) !important;
    border-color: rgba(0, 212, 255, 0.3) !important;
    transform: translateX(4px) !important;
}

.nav-section-header {
    color: #00d4ff !important;
    font-weight: 600 !important;
    font-size: 1.1rem !important;
    padding: 0.75rem 1rem !important;
    border-radius: 6px !important;
    transition: background 0.2s ease !important;
    cursor: pointer !important;
}

.nav-section-header:hover {
    background: rgba(0, 212, 255, 0.1) !important;
}

.nav-icon {
    font-size: 1.3rem !important;
    margin-right: 0.5rem !important;
}

.nav-title {
    font-weight: 600 !important;
}

.nav-link {
    display: block !important;
    padding: 0.75rem 1rem !important;
    color: #c8d0dd !important;
    text-decoration: none !important;
    border-radius: 6px !important;
    margin: 0.25rem 0 !important;
    transition: all 0.2s ease !important;
    font-size: 0.95rem !important;
    line-height: 1.5 !important;
}

.nav-link:hover {
    background: rgba(0, 123, 255, 0.15) !important;
    color: #00d4ff !important;
    transform: translateX(4px) !important;
    padding-left: 1.25rem !important;
}

.nav-link.active {
    background: linear-gradient(135deg, rgba(0, 123, 255, 0.2) 0%, rgba(0, 86, 179, 0.2) 100%) !important;
    color: #00d4ff !important;
    font-weight: 600 !important;
    border-left: 3px solid #007BFF !important;
}

.nav-lessons {
    margin-top: 0.5rem !important;
    padding-left: 0.5rem !important;
}


/* ========== РАЗВОРАЧИВАЮЩЕЕСЯ МЕНЮ ========== */

.nav-section-header {
    display: flex !important;
    align-items: center !important;
    justify-content: space-between !important;
    user-select: none !important;
}

.nav-arrow {
    font-size: 0.8rem !important;
    color: #00d4ff !important;
    transition: transform 0.3s ease !important;
    margin-left: auto !important;
    margin-right: 0.5rem !important;
}

.nav-section.expanded .nav-arrow {
    transform: rotate(0deg) !important;
}

.nav-section:not(.expanded) .nav-arrow {
    transform: rotate(-90deg) !important;
}

.nav-lessons {
    display: none !important;
    margin-top: 0.5rem !important;
    padding-left: 0.5rem !important;
    animation: slideDown 0.3s ease !important;
}

.nav-section.expanded .nav-lessons {
    display: block !important;
}

@keyframes slideDown {
    from {
        opacity: 0;
        max-height: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        max-height: 1000px;
        transform: translateY(0);
    }
}

.nav-section-header:hover {
    background: rgba(0, 212, 255, 0.1) !important;
}

.nav-section-header:active {
    background: rgba(0, 212, 255, 0.15) !important;
}


/* ========== МОБИЛЬНАЯ ВЕРСИЯ - ОПТИМИЗАЦИЯ ========== */

@media (max-width: 768px) {
    /* Основные настройки */
    body {
        font-size: 16px !important;
        line-height: 1.7 !important;
        overflow-x: hidden !important;
    }
    
    /* Sidebar - скрыт по умолчанию, показывается по клику */
    #sidebar {
        position: fixed !important;
        top: 0 !important;
        left: 0 !important;
        width: 85% !important;
        max-width: 320px !important;
        height: 100vh !important;
        z-index: 1000 !important;
        transform: translateX(-100%) !important;
        transition: transform 0.3s ease !important;
        box-shadow: 4px 0 20px rgba(0, 0, 0, 0.5) !important;
        overflow-y: auto !important;
        -webkit-overflow-scrolling: touch !important;
    }
    
    #sidebar.active {
        transform: translateX(0) !important;
    }
    
    /* Кнопка открытия меню */
    #toggleSidebar {
        display: block !important;
        position: fixed !important;
        top: 15px !important;
        left: 15px !important;
        z-index: 1001 !important;
        background: linear-gradient(135deg, #007BFF 0%, #0056b3 100%) !important;
        color: white !important;
        border: none !important;
        padding: 12px 16px !important;
        border-radius: 8px !important;
        font-size: 1.2rem !important;
        cursor: pointer !important;
        box-shadow: 0 4px 12px rgba(0, 123, 255, 0.4) !important;
    }
    
    /* Затемнение фона при открытом меню */
    .sidebar-overlay {
        position: fixed !important;
        top: 0 !important;
        left: 0 !important;
        width: 100% !important;
        height: 100% !important;
        background: rgba(0, 0, 0, 0.6) !important;
        z-index: 999 !important;
        display: none !important;
    }
    
    .sidebar-overlay.active {
        display: block !important;
    }
    
    /* Контент - занимает всю ширину */
    #contentWrapper {
        width: 100% !important;
        margin: 0 !important;
        padding: 70px 15px 30px 15px !important;
        max-width: 100% !important;
    }
    
    /* Заголовки */
    h1 {
        font-size: 1.75rem !important;
        line-height: 1.3 !important;
        margin-top: 1.5rem !important;
        margin-bottom: 1rem !important;
    }
    
    h2 {
        font-size: 1.5rem !important;
        line-height: 1.3 !important;
        margin-top: 2rem !important;
        margin-bottom: 1rem !important;
    }
    
    h3 {
        font-size: 1.25rem !important;
        line-height: 1.3 !important;
        margin-top: 1.5rem !important;
        margin-bottom: 0.75rem !important;
    }
    
    h4 {
        font-size: 1.1rem !important;
        line-height: 1.3 !important;
        margin-top: 1.25rem !important;
        margin-bottom: 0.5rem !important;
    }
    
    /* Параграфы */
    p {
        font-size: 1rem !important;
        line-height: 1.7 !important;
        margin-bottom: 1.25rem !important;
        word-wrap: break-word !important;
    }
    
    /* Списки */
    ul, ol {
        padding-left: 1.5rem !important;
        margin-bottom: 1.25rem !important;
    }
    
    li {
        margin-bottom: 0.5rem !important;
        line-height: 1.6 !important;
        font-size: 1rem !important;
    }
    
    /* Навигация */
    .nav-section {
        margin-bottom: 0.75rem !important;
        padding: 0.5rem !important;
    }
    
    .nav-section-header {
        font-size: 1rem !important;
        padding: 0.75rem !important;
    }
    
    .nav-icon {
        font-size: 1.1rem !important;
    }
    
    .nav-link {
        font-size: 0.9rem !important;
        padding: 0.6rem 0.75rem !important;
        line-height: 1.5 !important;
    }
    
    /* Блоки контента */
    .content-block {
        padding: 1.25rem !important;
        margin: 1.5rem 0 !important;
        border-radius: 10px !important;
    }
    
    .content-block h2,
    .content-block h3 {
        padding: 1rem !important;
        margin: 1.5rem 0 1rem 0 !important;
        font-size: 1.3rem !important;
    }
    
    /* Таблицы - горизонтальный скролл */
    table {
        display: block !important;
        width: 100% !important;
        overflow-x: auto !important;
        -webkit-overflow-scrolling: touch !important;
        margin: 1.5rem 0 !important;
    }
    
    table th,
    table td {
        padding: 0.75rem 0.5rem !important;
        font-size: 0.9rem !important;
        white-space: nowrap !important;
    }
    
    /* Step-by-step */
    .step {
        padding: 1.25rem !important;
        margin: 1.25rem 0 !important;
    }
    
    .step-number {
        width: 40px !important;
        height: 40px !important;
        font-size: 1.1rem !important;
    }
    
    .step-content {
        padding: 1rem !important;
        font-size: 0.95rem !important;
    }
    
    /* Поиск */
    #searchInput {
        width: 100% !important;
        padding: 12px !important;
        font-size: 1rem !important;
        margin-bottom: 1rem !important;
    }
    
    /* Кнопки */
    button {
        padding: 12px 20px !important;
        font-size: 1rem !important;
        min-height: 44px !important; /* Для удобного нажатия */
    }
    
    /* Улучшенная читаемость */
    div[style*="background: linear-gradient"] {
        padding: 1.25rem !important;
        margin: 1.5rem 0 !important;
        font-size: 0.95rem !important;
    }
    
    /* Убираем горизонтальный скролл */
    * {
        max-width: 100% !important;
        box-sizing: border-box !important;
    }
    
    /* Изображения */
    img {
        max-width: 100% !important;
        height: auto !important;
    }
}

/* Маленькие экраны */
@media (max-width: 480px) {
    #contentWrapper {
        padding: 70px 12px 25px 12px !important;
    }
    
    h1 {
        font-size: 1.5rem !important;
    }
    
    h2 {
        font-size: 1.3rem !important;
    }
    
    h3 {
        font-size: 1.15rem !important;
    }
    
    .content-block {
        padding: 1rem !important;
    }
    
    .nav-section-header {
        font-size: 0.95rem !important;
        padding: 0.6rem !important;
    }
    
    .nav-link {
        font-size: 0.85rem !important;
        padding: 0.5rem 0.6rem !important;
    }
}