/* ================================================
   ALPHABET BOOK - 3D Interactive Page Flip
   A vintage-inspired, tactile book experience
   ================================================ */

:root {
    /* Clean, modern palette with blue accent */
    --primary-color: #00a3fe;
    --primary-dark: #0082cc;
    --primary-light: #4dbfff;
    --paper-cream: #ffffff;
    --paper-white: #ffffff;
    --paper-shadow: #b0b8c0;
    --paper-edge: #e8eaed;
    --leather-brown: #00a3fe;
    --leather-dark: #0082cc;
    --gold-accent: #00a3fe;
    --gold-light: #4dbfff;
    --ink-black: #1a2530;
    --ink-soft: #4a5568;
    
    /* Book dimensions - taller to fit caption below image */
    /* Image is 1536x1024 (3:2), plus ~120px for caption */
    --page-width: min(768px, 85vw);
    --page-height: calc(var(--page-width) * 0.667 + 140px);
    
    /* Animation timing - slightly slower for elegance */
    --flip-duration: 1s;
    --flip-easing: cubic-bezier(0.4, 0.0, 0.2, 1.0);
}

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

body {
    min-height: 100vh;
    font-family: 'Crimson Pro', Georgia, serif;
    background: #ffffff;
    overflow-x: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
} */

/* Ambient lighting effect */
.alphabet .scene {
    position: relative;
    width: 100%;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

/* Interface Language Selector (top right) */
.alphabet .interface-lang-selector {
    position: fixed;
    top: 1rem;
    right: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    z-index: 1000;
    background: #ffffff;
    padding: 0.5rem 0.8rem;
    border-radius: 6px;
    border: 1px solid var(--paper-edge);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.alphabet .interface-label {
    font-family: 'Crimson Pro', serif;
    font-size: 0.85rem;
    color: var(--ink-soft);
    margin-right: 0.3rem;
}

.alphabet .ui-lang-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 28px;
    background: var(--paper-edge);
    border: 1px solid transparent;
    border-radius: 4px;
    color: var(--ink-soft);
    text-decoration: none;
    font-family: 'Crimson Pro', serif;
    font-size: 0.8rem;
    font-weight: 600;
    transition: all 0.2s ease;
}

.alphabet .ui-lang-btn:hover {
    background: var(--primary-light);
    border-color: var(--primary-color);
    color: #ffffff;
}

.alphabet .ui-lang-btn.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: #ffffff;
}

.alphabet .ambient-light {
    display: none;
}

.alphabet .book-container {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

/* ================================================
   LANGUAGE SELECTOR
   ================================================ */

.alphabet .language-selector {
    display: flex;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.alphabet .lang-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0.5rem 1.2rem;
    background: var(--paper-edge);
    border: 2px solid transparent;
    border-radius: 6px;
    color: var(--ink-soft);
    text-decoration: none;
    font-family: 'Crimson Pro', serif;
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    transition: all 0.3s ease;
    cursor: pointer;
}

.alphabet .lang-btn:hover {
    background: var(--primary-light);
    border-color: var(--primary-color);
    color: #ffffff;
    transform: translateY(-2px);
}

.alphabet .lang-btn.active {
    background: linear-gradient(145deg, var(--primary-color), var(--primary-dark));
    border-color: var(--primary-color);
    color: #ffffff;
    box-shadow: 
        0 4px 15px rgba(0, 163, 254, 0.3),
        inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

.alphabet .book-title {
    /* font-family: 'Playfair Display', serif; */
    font-size: clamp(1.8rem, 5vw, 3rem);
    color: var(--primary-color);
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

/* ================================================
   THE BOOK - 3D Container
   ================================================ */

.alphabet .book {
    position: relative;
    width: var(--page-width);
    height: var(--page-height);
    perspective: 2000px;
    perspective-origin: center center;
    transform-style: preserve-3d;
    box-shadow: 
        0 10px 30px rgba(0, 0, 0, 0.15),
        0 20px 60px rgba(0, 0, 0, 0.1),
        0 0 0 1px rgba(0, 0, 0, 0.05);
    border-radius: 0 8px 8px 0;
}

/* Book shadow on the "table" - hidden for clean look */
.alphabet .book::before {
    display: none;
}

/* ================================================
   PAGE STRUCTURE
   Each page is a 3D element with front and back
   ================================================ */

.alphabet .page {
    position: absolute;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transform-origin: left center;
    transition: transform var(--flip-duration) var(--flip-easing),
                z-index 0s linear calc(var(--flip-duration) / 2);
    cursor: pointer;
    
    /* Shadow properties - initialized to prevent flash */
    --rotation: 0;
    --shadow-intensity: 0;
    --shadow-offset-x: 0;
    --shadow-offset-y: 0;
    --shadow-blur: 0;
}

.alphabet .page.flipped {
    transform: rotateY(-180deg);
}

.alphabet .page.flipping {
    z-index: 1000 !important;
}

/* Default state for page shadow overlay - hidden */
.alphabet .page::after {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0);
    pointer-events: none;
    z-index: 100;
    border-radius: 0 6px 6px 0;
    opacity: 0;
    transition: opacity 0.15s ease-out;
}

.alphabet .page.receiving-shadow::after {
    opacity: 1;
}

/* Front and back faces */
.alphabet .page-front,
.alphabet .page-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 0 6px 6px 0;
    overflow: hidden;
}

.alphabet .page-front {
    z-index: 2;
    background: var(--paper-cream);
    box-shadow: 
        inset -4px 0 8px rgba(0, 0, 0, 0.1),
        inset 0 0 15px rgba(0, 0, 0, 0.03);
}

/* Ensure all front content respects backface visibility */
.alphabet .page-front,
.alphabet .page-front .page-content,
.alphabet .page-front .page-image,
.alphabet .page-front .page-caption,
.alphabet .page-front .page-caption *,
.alphabet .page-front .caption-main-row,
.alphabet .page-front .caption-letter,
.alphabet .page-front .caption-word,
.alphabet .page-front .caption-description,
.alphabet .page-front .audio-btn,
.alphabet .page-front img {
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

/* Spine/fold shadow on page - covers entire page including caption */
.alphabet .page::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 30px;
    height: 100%;
    background: linear-gradient(
        to right,
        rgba(0, 0, 0, 0.15) 0%,
        rgba(0, 0, 0, 0.06) 40%,
        transparent 100%
    );
    pointer-events: none;
    z-index: 200;
    border-radius: 0 0 0 6px;
    backface-visibility: hidden;
}

/* Hide fold shadow on flipped pages */
.alphabet .page.flipped::before {
    opacity: 0;
}


/* Back side - slightly off-white, fully opaque */
.alphabet .page-back {
    transform: rotateY(180deg);
    z-index: 1;
    background: #e5e5e5 !important;
    /* Large inset shadow to ensure uniform color coverage */
    box-shadow: inset 0 0 0 1000px #e5e5e5;
}

/* Ensure back content matches */
.alphabet .page-back .page-content {
    background: #e5e5e5 !important;
    position: relative;
    /* Large inset shadow to ensure uniform color coverage */
    box-shadow: inset 0 0 0 1000px #e5e5e5;
}

/* Overlay to ensure no bleed-through */
.alphabet .page-back .page-content::before {
    content: '';
    position: absolute;
    inset: 0;
    background: #e5e5e5;
    z-index: 1;
}

/* Hide any content on backs except back-cover */
.alphabet .page-back .page-content:not(.back-cover) * {
    display: none;
}

/* Spine shadow on back (appears on left when flipped) */
.alphabet .page-back::before {
    content: '';
    position: absolute;
    right: 0;
    top: 0;
    width: 25px;
    height: 100%;
    background: linear-gradient(
        to left,
        rgba(0, 0, 0, 0.08) 0%,
        rgba(0, 0, 0, 0.03) 40%,
        transparent 100%
    );
    pointer-events: none;
    z-index: 10;
}

/* Content wrapper */
.alphabet .page-content {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    transform-style: flat;
}

.alphabet .page-content img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
}

/* Page with caption below image */
.alphabet .page-content.with-caption {
    flex-direction: column;
    background: var(--paper-cream);
    justify-content: flex-start;
}

/* Cover page - full image without caption */
.alphabet .page-content.cover-page {
    background: var(--paper-cream);
}

.alphabet .page-content.cover-page img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
}

.alphabet .page-image {
    width: 100%;
    /* Fixed height based on 3:2 aspect ratio of 1536x1024 images */
    height: calc(var(--page-width) * 0.667);
    flex-shrink: 0;
    overflow: hidden;
}

.alphabet .page-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
}

/* Caption below the image */
.alphabet .page-caption {
    width: 100%;
    flex: 1;
    padding: 0.6rem 1rem;
    background: var(--paper-cream);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.15rem;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

/* Main row with letter, audio button, and word on same line */
.alphabet .caption-main-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    flex-wrap: wrap;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.alphabet .caption-letter {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1;
}

/* Audio button */
.alphabet .audio-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: linear-gradient(145deg, var(--primary-color), var(--primary-dark));
    border: 2px solid var(--primary-light);
    border-radius: 50%;
    color: #ffffff;
    cursor: pointer;
    transition: all 0.2s ease;
    flex-shrink: 0;
    position: relative;
    z-index: 50;
    pointer-events: auto !important;
    box-shadow: 0 2px 8px rgba(0, 163, 254, 0.3);
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.alphabet .audio-btn svg {
    pointer-events: none;
}

.alphabet .audio-btn svg {
    width: 18px;
    height: 18px;
}

.alphabet .audio-btn:hover {
    background: linear-gradient(145deg, var(--primary-dark), var(--primary-color));
    transform: scale(1.1);
    box-shadow: 0 4px 15px rgba(0, 163, 254, 0.4);
}

.alphabet .audio-btn:active {
    transform: scale(0.95);
}

.alphabet .audio-btn.playing {
    background: var(--primary-light);
    color: #ffffff;
    animation: pulse 1s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { box-shadow: 0 0 0 0 rgba(0, 163, 254, 0.4); }
    50% { box-shadow: 0 0 0 8px rgba(0, 163, 254, 0); }
}

.alphabet .caption-word {
    font-family: 'Crimson Pro', serif;
    font-size: clamp(1.1rem, 2.5vw, 1.5rem);
    font-weight: 600;
    color: var(--ink-soft);
    letter-spacing: 0.05em;
}

.alphabet .caption-description {
    font-family: 'Crimson Pro', serif;
    font-size: clamp(0.85rem, 1.8vw, 1rem);
    font-style: italic;
    color: var(--ink-soft);
    opacity: 0.8;
    text-align: center;
    max-width: 95%;
    line-height: 1.3;
}

/* Description for placeholder pages */
.alphabet .placeholder-page .letter-description {
    font-family: 'Crimson Pro', serif;
    font-size: clamp(1rem, 2.5vw, 1.3rem);
    font-style: italic;
    color: var(--ink-soft);
    opacity: 0.8;
    text-align: center;
    max-width: 80%;
    line-height: 1.4;
}

/* ================================================
   PLACEHOLDER PAGES (Alphabet)
   ================================================ */

.alphabet .placeholder-page {
    background: linear-gradient(
        145deg,
        #ffffff 0%,
        #f8fafc 100%
    );
    flex-direction: column;
    gap: 1.5rem;
    position: relative;
}

/* Decorative border */
.alphabet .placeholder-page::before {
    content: '';
    position: absolute;
    inset: 20px;
    border: 3px double var(--primary-light);
    border-radius: 4px;
    pointer-events: none;
}

/* Corner flourishes */
.alphabet .placeholder-page::after {
    content: '❧';
    position: absolute;
    bottom: 30px;
    right: 35px;
    font-size: 1.5rem;
    color: var(--primary-light);
    opacity: 0.6;
}

/* Main row for placeholder pages - letter, audio, word on same line */
.alphabet .placeholder-page .letter-main-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
    position: relative;
    z-index: 150;
}

.alphabet .placeholder-page .letter {
    font-family: 'Playfair Display', serif;
    font-size: clamp(6rem, 20vw, 12rem);
    font-weight: 700;
    color: var(--primary-color);
    text-shadow: 
        4px 4px 0 var(--primary-light),
        6px 6px 0 rgba(0, 0, 0, 0.05);
    line-height: 1;
    transition: transform 0.3s ease;
}

.alphabet .placeholder-page .letter-word {
    font-family: 'Crimson Pro', serif;
    font-size: clamp(2rem, 6vw, 4rem);
    font-style: italic;
    color: var(--ink-soft);
    letter-spacing: 0.1em;
}

.alphabet .page:hover .placeholder-page .letter {
    transform: scale(1.02);
}

/* Larger audio button for placeholder pages */
.alphabet .audio-btn-large {
    width: 50px;
    height: 50px;
}

.alphabet .audio-btn-large svg {
    width: 24px;
    height: 24px;
}

/* Last page back - "The End" cover */
.alphabet .placeholder-page.back.end {
    background: linear-gradient(
        145deg,
        var(--primary-color) 0%,
        var(--primary-dark) 100%
    );
}

.alphabet .placeholder-page.back.end::before,
.alphabet .placeholder-page.back.end::after {
    display: none;
}

.alphabet .placeholder-page.back.end .back-info {
    font-family: 'Playfair Display', serif;
    font-size: 2rem;
    color: #ffffff;
}

/* Back cover for last page */
.alphabet .back-cover {
    background: linear-gradient(
        145deg,
        var(--primary-color) 0%,
        var(--primary-dark) 100%
    );
    color: #ffffff;
    font-family: 'Playfair Display', serif;
    font-size: 2rem;
}

/* ================================================
   FLIP ANIMATION ENHANCEMENTS
   ================================================ */

/* Shadow overlay on the NEXT page (the one being revealed) */
/* The turning page casts shadow onto the page below - covers entire page including caption */
.alphabet .page.receiving-shadow::after {
    background: rgba(0, 0, 0, calc(var(--shadow-intensity) * 0.55));
}

/* Hide front content when page is past 90° (showing-back class added at 90°) */
.alphabet .page.showing-back .page-front .page-caption,
.alphabet .page.showing-back .page-front .page-caption *,
.alphabet .page.showing-back .page-front .page-image,
.alphabet .page.showing-back .page-front .page-image * {
    visibility: hidden !important;
    opacity: 0 !important;
    transition: none !important;
}

/* Also hide on fully flipped pages (not during animation) */
.alphabet .page.flipped:not(.flipping) .page-front .page-caption,
.alphabet .page.flipped:not(.flipping) .page-front .page-caption *,
.alphabet .page.flipped:not(.flipping) .page-front .page-image,
.alphabet .page.flipped:not(.flipping) .page-front .page-image * {
    visibility: hidden !important;
    opacity: 0 !important;
    transition: none !important;
}

/* When page is past 90° and showing back, ensure consistent color */
.alphabet .page.showing-back .page-back,
.alphabet .page.flipped .page-back {
    background: #e5e5e5 !important;
    box-shadow: inset 0 0 0 1000px #e5e5e5 !important;
}

.alphabet .page.showing-back .page-back .page-content,
.alphabet .page.flipped .page-back .page-content {
    background: #e5e5e5 !important;
    box-shadow: inset 0 0 0 1000px #e5e5e5 !important;
}

.alphabet .page.showing-back .page-back .page-content::before,
.alphabet .page.flipped .page-back .page-content::before {
    background: #e5e5e5 !important;
}

/* Overlay on back during flip and when flipped - covers entire page uniformly */
.alphabet .page.flipping .page-back::after,
.alphabet .page.flipped .page-back::after {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    background: #e5e5e5;
    pointer-events: none;
    z-index: 999;
    border-radius: 0 6px 6px 0;
}

/* ================================================
   CONTROLS
   ================================================ */

.alphabet .controls {
    display: flex;
    align-items: center;
    gap: 2rem;
    margin-top: 1rem;
}

.alphabet .nav-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.8rem 1.5rem;
    background: linear-gradient(
        145deg,
        var(--primary-color) 0%,
        var(--primary-dark) 100%
    );
    border: 2px solid var(--primary-light);
    border-radius: 4px;
    color: #ffffff;
    font-family: 'Crimson Pro', serif;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 
        0 4px 15px rgba(0, 163, 254, 0.3),
        inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

.alphabet .nav-btn:hover {
    background: linear-gradient(
        145deg,
        var(--primary-dark) 0%,
        var(--primary-color) 100%
    );
    border-color: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: 
        0 6px 20px rgba(0, 163, 254, 0.4),
        inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

.alphabet .nav-btn:active {
    transform: translateY(0);
    box-shadow: 
        0 2px 10px rgba(0, 0, 0, 0.3),
        inset 0 1px 0 rgba(255, 255, 255, 0.1);
}

.alphabet .nav-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.alphabet .nav-btn svg {
    width: 20px;
    height: 20px;
}

.alphabet .page-indicator {
    display: flex;
    align-items: center;
    gap: 0.3rem;
    font-family: 'Playfair Display', serif;
    font-size: 1.3rem;
    color: var(--primary-color);
}

.alphabet .page-indicator .separator {
    opacity: 0.5;
}

.alphabet .instructions {
    font-family: 'Crimson Pro', serif;
    font-style: italic;
    color: var(--ink-soft);
    font-size: 0.95rem;
    opacity: 0.8;
}

/* ================================================
   CLICK ZONES FOR PAGE TURNING
   ================================================ */

/* Entire page is clickable */
.alphabet .page {
    cursor: pointer;
}

.alphabet .page.flipping {
    cursor: default;
}

/* Hover effect - subtle lift and shadow */
.alphabet .page:not(.flipped):not(.flipping):hover {
    transform: rotateY(-2deg);
    filter: drop-shadow(-3px 3px 8px rgba(0, 0, 0, 0.15));
}

.alphabet .page:not(.flipped):not(.flipping):hover .page-front {
    box-shadow: 
        inset -4px 0 8px rgba(0, 0, 0, 0.12),
        inset 0 0 15px rgba(0, 0, 0, 0.04);
}

/* Disable hover effects on flipped pages to keep back white */
.alphabet .page.flipped:not(.flipping):hover {
    transform: rotateY(-180deg);
}

/* ================================================
   RESPONSIVE ADJUSTMENTS
   ================================================ */

@media (max-width: 900px) {
    :root {
        --page-width: 90vw;
    }
    
    .alphabet .book-title {
        font-size: 1.5rem;
    }
    
    .alphabet .language-selector {
        gap: 0.5rem;
    }
    
    .alphabet .lang-btn {
        padding: 0.4rem 0.7rem;
        font-size: 0.85rem;
    }
    
    .alphabet .controls {
        gap: 1rem;
    }
    
    .alphabet .nav-btn {
        padding: 0.6rem 1rem;
        font-size: 0.9rem;
    }
    
    .alphabet .nav-btn span {
        display: none;
    }
    
    .alphabet .placeholder-page::before {
        inset: 10px;
        border-width: 2px;
    }
}

@media (max-width: 600px) {
    :root {
        --page-height: calc(var(--page-width) * 0.667 + 240px);
    }

    .alphabet .scene {
        padding: 1rem;
        min-height: 50vh;
    }
    
    .alphabet .book-container {
        gap: 1rem;
    }
    
    .alphabet .language-selector {
        gap: 0.4rem;
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .alphabet .lang-btn {
        padding: 0.35rem 0.6rem;
        font-size: 0.85rem;
    }
    
    .alphabet .instructions {
        font-size: 0.8rem;
        text-align: center;
    }
}

/* ================================================
   ACCESSIBILITY
   ================================================ */

@media (prefers-reduced-motion: reduce) {
    .alphabet .page {
        transition: transform 0.1s ease;
    }
    
    .alphabet .page.flipping {
        animation: none;
    }
    
    @keyframes edgeGlow {
        0%, 100% {
            opacity: 0.7;
        }
    }
}

/* Focus states */
.alphabet .nav-btn:focus-visible {
    outline: 2px solid var(--primary-light);
    outline-offset: 3px;
}

.alphabet .page:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: -5px;
}