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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--tg-theme-text-color, #000);
    background: var(--tg-theme-bg-color, #fff);
    overflow-x: hidden;
}

.container {
    max-width: 100%;
    margin: 0 auto;
    padding: 0;
    min-height: 100vh;
}

/* Экран загрузки */
.loading-screen {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    background: var(--tg-theme-bg-color, #fff);
}

.loader {
    width: 40px;
    height: 40px;
    border: 3px solid var(--tg-theme-hint-color, #999);
    border-top: 3px solid var(--tg-theme-link-color, #2481cc);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-screen p {
    color: var(--tg-theme-hint-color, #999);
    font-size: 16px;
}

/* Основной контент */
.content-hidden {
    display: none;
}

.content-visible {
    display: block;
    animation: fadeIn 0.3s ease-in;
}

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

/* Заголовок статьи */
.article-header {
    padding: 20px;
    border-bottom: 1px solid var(--tg-theme-hint-color, #e0e0e0);
    background: var(--tg-theme-secondary-bg-color, #f8f9fa);
}

.article-header h1 {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--tg-theme-text-color, #000);
    line-height: 1.3;
}

.description {
    font-size: 16px;
    color: var(--tg-theme-hint-color, #666);
    margin-bottom: 15px;
    line-height: 1.5;
}

.meta-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

.date {
    font-size: 14px;
    color: var(--tg-theme-hint-color, #999);
    background: var(--tg-theme-bg-color, #fff);
    padding: 5px 10px;
    border-radius: 12px;
    border: 1px solid var(--tg-theme-hint-color, #e0e0e0);
}

/* Навигация по разделам */
.sections-nav {
    padding: 15px 20px 0;
    background: var(--tg-theme-bg-color, #fff);
    border-bottom: 1px solid var(--tg-theme-hint-color, #e0e0e0);
}

.nav-buttons {
    display: flex;
    gap: 10px;
    overflow-x: auto;
    padding-bottom: 15px;
}

.nav-btn {
    flex-shrink: 0;
    padding: 10px 20px;
    border: 2px solid var(--tg-theme-hint-color, #e0e0e0);
    background: var(--tg-theme-bg-color, #fff);
    color: var(--tg-theme-text-color, #000);
    border-radius: 20px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.nav-btn.active {
    background: var(--tg-theme-button-color, #2481cc);
    color: var(--tg-theme-button-text-color, #fff);
    border-color: var(--tg-theme-button-color, #2481cc);
}

/* Прогресс чтения */
.reading-progress {
    height: 3px;
    background: var(--tg-theme-hint-color, #e0e0e0);
    position: sticky;
    top: 0;
    z-index: 100;
}

.progress-bar {
    height: 100%;
    background: var(--tg-theme-link-color, #2481cc);
    width: 0%;
    transition: width 0.3s ease;
}

/* Содержимое статьи */
.article-content {
    padding: 0;
}

.content-section {
    display: none;
    padding: 25px 20px;
    line-height: 1.8;
}

.content-section.active {
    display: block;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateX(20px); }
    to { opacity: 1; transform: translateX(0); }
}

.section-title {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--tg-theme-text-color, #000);
    border-left: 4px solid var(--tg-theme-link-color, #2481cc);
    padding-left: 15px;
}

.section-content {
    font-size: 16px;
    color: var(--tg-theme-text-color, #000);
    text-align: justify;
}

/* Навигация между секциями */
.section-navigation {
    display: flex;
    justify-content: space-between;
    padding: 20px;
    background: var(--tg-theme-secondary-bg-color, #f8f9fa);
    border-top: 1px solid var(--tg-theme-hint-color, #e0e0e0);
    margin-top: 30px;
}

.nav-section-btn {
    padding: 12px 24px;
    border: none;
    background: var(--tg-theme-button-color, #2481cc);
    color: var(--tg-theme-button-text-color, #fff);
    border-radius: 25px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.nav-section-btn:disabled {
    background: var(--tg-theme-hint-color, #999);
    cursor: not-allowed;
    opacity: 0.6;
}

/* Экран ошибки */
.error-screen {
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    padding: 20px;
    text-align: center;
}

.error-screen.show {
    display: flex;
}

.error-icon {
    font-size: 60px;
    margin-bottom: 20px;
}

.retry-btn {
    padding: 12px 30px;
    background: var(--tg-theme-button-color, #2481cc);
    color: var(--tg-theme-button-text-color, #fff);
    border: none;
    border-radius: 25px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
}