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

:root {
    --bg-color: #050505;
    --surface-color: #1E1F23;
    --surface-hover: #2A2C31;
    --text-primary: #F5F5F7;
    --text-secondary: #8A8D94;
    --border-color: #3C3F45;
    --accent-color: #6366F1;
    --accent-hover: #818CF8;
    --progress-color: #6366F1;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    background-color: rgba(5, 5, 5, 0.9);
    -webkit-backdrop-filter: blur(20px);
    backdrop-filter: blur(20px);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid var(--border-color);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

h1 {
    font-size: 1.1rem;
    font-weight: 500;
    letter-spacing: 0.02em;
    color: var(--text-primary);
    text-transform: uppercase;
}

.language-selector {
    display: flex;
    gap: 0.5rem;
}

.lang-btn {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 0.4rem 0.75rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: all 0.2s ease;
    font-weight: 500;
    letter-spacing: 0.05em;
}

.lang-btn:hover {
    border-color: var(--text-secondary);
    color: var(--text-primary);
}

.lang-btn.active {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    color: white;
}

/* Chapter Navigation - Top */
.chapter-nav {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0.75rem 2rem;
    gap: 1rem;
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
}

.chapter-selector {
    flex: 0 1 400px;
}

#chapter-select {
    width: 100%;
    padding: 0.6rem 2.5rem 0.6rem 1rem;
    background-color: var(--bg-color);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.9rem;
    cursor: pointer;
    font-family: inherit;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%238A8D94' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
}

#chapter-select:focus {
    outline: none;
    border-color: var(--accent-color);
}

#chapter-select option {
    background-color: var(--surface-color);
    color: var(--text-primary);
}

/* Main Content */
main {
    flex: 1;
    padding: 4rem 2rem;
    position: relative;
}

#chapter-content {
    max-width: 700px;
    margin: 0 auto;
}

#chapter-title {
    font-family: 'Literata', 'Source Serif 4', 'Georgia', serif;
    font-size: 2rem;
    font-weight: 500;
    letter-spacing: -0.01em;
    margin-bottom: 3rem;
    color: var(--text-primary);
    line-height: 1.3;
    font-optical-sizing: auto;
    text-align: center;
}

#chapter-text {
    font-family: 'Literata', 'Source Serif 4', 'Georgia', serif;
    font-size: 1.15rem;
    line-height: 1.9;
    color: var(--text-primary);
    font-optical-sizing: auto;
    letter-spacing: 0.01em;
    font-weight: 400;
}

#chapter-text p {
    margin-bottom: 1.5em;
    text-align: left;
    text-indent: 0;
    -webkit-hyphens: auto;
    hyphens: auto;
}

#chapter-text em {
    font-style: italic;
    color: var(--text-secondary);
}

#chapter-text strong {
    font-weight: 600;
    color: var(--text-primary);
}

#chapter-text hr {
    margin: 3rem auto;
    border: none;
    height: 1px;
    background: linear-gradient(to right, transparent, var(--border-color), transparent);
    width: 30%;
}

/* Side Navigation Arrows - Kindle Style */
.side-nav {
    position: fixed;
    top: 50%;
    transform: translateY(-50%);
    z-index: 50;
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
}

.side-nav.visible {
    opacity: 1;
    pointer-events: auto;
}

.side-nav.prev {
    left: 1rem;
}

.side-nav.next {
    right: 1rem;
}

.side-nav-btn {
    width: 60px;
    height: 120px;
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    color: var(--text-secondary);
}

.side-nav-btn:hover {
    background-color: var(--surface-hover);
    border-color: var(--accent-color);
    color: var(--accent-color);
    transform: scale(1.05);
}

.side-nav-btn:disabled {
    opacity: 0.2;
    cursor: not-allowed;
    pointer-events: none;
}

.side-nav-btn svg {
    width: 32px;
    height: 32px;
    fill: currentColor;
}

/* Bottom Chapter Navigation */
.chapter-nav-bottom {
    max-width: 700px;
    margin: 4rem auto 0;
    padding-top: 3rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: stretch;
    gap: 1.5rem;
}

.chapter-link {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    text-decoration: none;
    color: var(--text-primary);
    transition: all 0.25s ease;
    cursor: pointer;
}

.chapter-link:hover {
    background-color: var(--surface-hover);
    border-color: var(--accent-color);
    transform: translateY(-3px);
}

.chapter-link.disabled {
    opacity: 0.3;
    pointer-events: none;
}

.chapter-link.prev {
    text-align: left;
}

.chapter-link.next {
    text-align: right;
}

.chapter-link-label {
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.chapter-link-title {
    font-family: 'Literata', 'Source Serif 4', 'Georgia', serif;
    font-size: 0.95rem;
    font-weight: 500;
    line-height: 1.4;
    color: var(--text-primary);
}

.chapter-link-arrow {
    font-size: 1.5rem;
    margin-top: 0.75rem;
    color: var(--text-secondary);
}

/* Progress Indicator */
.progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-color), var(--accent-hover));
    z-index: 1000;
    transition: width 0.1s ease;
}

/* Footer */
footer {
    padding: 2rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.8rem;
    border-top: 1px solid var(--border-color);
    background-color: var(--surface-color);
}

/* Loading State */
.loading {
    text-align: center;
    padding: 4rem;
    color: var(--text-secondary);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .side-nav.prev {
        left: 0.5rem;
    }
    .side-nav.next {
        right: 0.5rem;
    }
    .side-nav-btn {
        width: 50px;
        height: 100px;
    }
    .side-nav-btn svg {
        width: 28px;
        height: 28px;
    }
}

@media (max-width: 900px) {
    .side-nav {
        display: none;
    }
}

@media (max-width: 768px) {
    header {
        padding: 0.75rem 1rem;
    }

    .header-content {
        flex-direction: column;
        gap: 0.75rem;
    }

    h1 {
        font-size: 1rem;
    }

    .lang-btn {
        padding: 0.35rem 0.6rem;
        font-size: 0.75rem;
    }

    .chapter-nav {
        padding: 0.75rem 1rem;
    }

    .chapter-selector {
        flex: 1;
        width: 100%;
        max-width: 100%;
    }

    main {
        padding: 2.5rem 1.25rem;
    }

    #chapter-title {
        font-size: 1.5rem;
        margin-bottom: 2rem;
    }

    #chapter-text {
        font-size: 1.05rem;
        line-height: 1.8;
    }

    .chapter-nav-bottom {
        flex-direction: column;
        gap: 1rem;
        margin-top: 3rem;
        padding-top: 2rem;
    }

    .chapter-link {
        padding: 1.25rem;
    }

    .chapter-link.prev,
    .chapter-link.next {
        text-align: left;
    }
}

/* Smooth scroll behavior */
html {
    scroll-behavior: smooth;
}

/* Selection styling */
::selection {
    background: var(--accent-color);
    color: white;
}

/* Focus styles for accessibility */
:focus-visible {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* Scrollbar styling */
::-webkit-scrollbar {
    width: 8px;
}

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

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

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}