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

:root {
    --clr-primary: #6c5ce7;
    --clr-primary-light: #a29bfe;
    --clr-accent: #fd79a8;
    --clr-accent-light: #fab1a0;
    --clr-bg: #f8f9ff;
    --clr-card: #ffffff;
    --clr-text: #2d3436;
    --clr-text-light: #636e72;
    --clr-border: #dfe6e9;
    --radius: 16px;
    --radius-sm: 10px;
    --shadow: 0 4px 20px rgba(108, 92, 231, 0.12);
    --shadow-hover: 0 8px 30px rgba(108, 92, 231, 0.22);
    --transition: 0.25s ease;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--clr-bg);
    color: var(--clr-text);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ── Header ── */

.header {
    background: linear-gradient(135deg, var(--clr-primary) 0%, var(--clr-accent) 100%);
    color: #fff;
    text-align: center;
    padding: 2.5rem 1rem 2rem;
    border-radius: 0 0 32px 32px;
    box-shadow: var(--shadow);
}

.header--compact {
    padding: 1.2rem 1rem;
    border-radius: 0 0 20px 20px;
}

.header__title {
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -0.5px;
}

.header__subtitle {
    margin-top: 0.4rem;
    font-size: 1rem;
    opacity: 0.9;
}

/* ── Content ── */

.content {
    flex: 1;
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.content--centered {
    display: flex;
    flex-direction: column;
    align-items: center;
}

/* ── Table of Contents ── */

.toc {
    margin-bottom: 2.5rem;
}

.toc__title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--clr-primary);
}

.toc__grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    gap: 1rem;
}

.toc__card {
    background: var(--clr-card);
    border-radius: var(--radius-sm);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform var(--transition), box-shadow var(--transition);
    display: block;
    text-decoration: none;
    color: var(--clr-text);
}

.toc__card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.toc__card-img {
    width: 100%;
    height: 170px;
    object-fit: contain;
    background: #eee;
    display: block;
}

.toc__card-label {
    display: block;
    text-align: center;
    padding: 0.5rem;
    font-size: 0.85rem;
    font-weight: 600;
    background: var(--clr-card);
}

/* ── Quick Nav (TOC page) ── */

.quick-nav {
    background: var(--clr-card);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.quick-nav__title {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 0.8rem;
    color: var(--clr-primary);
}

.quick-nav__input-group {
    display: flex;
    gap: 0.5rem;
}

/* ── Page View ── */

.page-view__wrapper {
    background: var(--clr-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1rem;
    margin-bottom: 1.5rem;
    max-width: 700px;
    width: 100%;
    display: flex;
    justify-content: center;
}

.page-view__image {
    max-width: 100%;
    max-height: 75vh;
    border-radius: var(--radius-sm);
    display: block;
}

.page-view__nav {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.page-view__counter {
    font-weight: 700;
    font-size: 1rem;
    color: var(--clr-primary);
    min-width: 100px;
    text-align: center;
}

.page-view__quick {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.page-view__input {
    width: 90px;
    padding: 0.6rem 0.8rem;
    border: 2px solid var(--clr-border);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    text-align: center;
    outline: none;
    transition: border-color var(--transition);
}

.page-view__input:focus {
    border-color: var(--clr-primary);
}

/* ── Buttons ── */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.6rem 1.2rem;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition), transform var(--transition);
    text-decoration: none;
    white-space: nowrap;
}

.btn:active {
    transform: scale(0.96);
}

.btn--primary {
    background: linear-gradient(135deg, var(--clr-primary), var(--clr-accent));
    color: #fff;
}

.btn--primary:hover {
    filter: brightness(1.1);
}

.btn--nav {
    background: var(--clr-card);
    color: var(--clr-text);
    border: 2px solid var(--clr-border);
}

.btn--nav:hover {
    border-color: var(--clr-primary);
    color: var(--clr-primary);
}

/* ── Footer ── */

.footer {
    text-align: center;
    padding: 1.2rem;
    color: var(--clr-text-light);
    font-size: 0.85rem;
}

/* ── Responsive ── */

@media (max-width: 600px) {
    .header__title {
        font-size: 1.5rem;
    }

    .toc__grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    }

    .toc__card-img {
        height: 130px;
    }

    .page-view__nav {
        gap: 0.4rem;
    }

    .btn {
        padding: 0.5rem 0.8rem;
        font-size: 0.85rem;
    }
}