:root {
    --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --glass-bg: rgba(255, 255, 255, 0.85);
    --glass-border: rgba(255, 255, 255, 0.95);
    --brand-blue: #00bcd4;
    --brand-pink: #e91e63;
}

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

body { 
    font-family: var(--font-main); 
    margin: 0; 
    overflow: hidden; 
    background-color: #e0f7fa;
    background-image: radial-gradient(circle, #e0f7fa 0%, #b2ebf2 100%);
    touch-action: manipulation;
}

a { text-decoration: none; }

.reader-environment { display: flex; flex-direction: column; width: 100vw; height: 100vh; position: relative; }

/* Header UI */
.reader-header { display: flex; justify-content: space-between; align-items: center; padding: 15px 30px; z-index: 100; flex-shrink: 0; }
.glass-panel { background: var(--glass-bg); backdrop-filter: blur(15px); -webkit-backdrop-filter: blur(15px); border-bottom: 2px solid var(--glass-border); box-shadow: 0 8px 32px rgba(0,0,0,0.15); }

.btn-nav { background: white; color: #333; font-weight: 900; padding: 12px 28px; border-radius: 30px; box-shadow: 0 4px 10px rgba(0,0,0,0.15); text-transform: uppercase; letter-spacing: 1px; transition: transform 0.2s; }
.btn-nav:hover { transform: scale(1.05); }
.btn-nav:active { transform: scale(0.95); }

/* Book Stage & Board Book Styling */
.book-stage { 
    flex-grow: 1; display: flex; flex-direction: column; justify-content: center; align-items: center; 
    padding: 20px; overflow: hidden;
}

.book-frame {
    position: relative;
    width: 100%;
    max-width: 1100px;
    aspect-ratio: 16 / 9;
    background: #fff;
    border-radius: 20px;
    
    /* Simulate a thick board book structure */
    box-shadow: 
        0 25px 50px rgba(0,0,0,0.3), 
        0 0 0 6px #ffffff,
        0 0 0 10px #cbd5e1,
        inset 0 0 15px rgba(0,0,0,0.1);
        
    overflow: hidden;
    margin-bottom: 25px;
}

.spine-line {
    position: absolute;
    top: 0; left: 50%;
    width: 60px; height: 100%;
    transform: translateX(-50%);
    background: linear-gradient(to right, transparent 0%, rgba(0,0,0,0.1) 40%, rgba(0,0,0,0.2) 50%, rgba(0,0,0,0.1) 60%, transparent 100%);
    z-index: 50;
    pointer-events: none;
}

.page-slider {
    position: relative;
    width: 100%;
    height: 100%;
}

.page-slide {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.4s ease-in-out;
}

.page-slide.active {
    opacity: 1;
    pointer-events: auto;
}

.page-media {
    width: 100%; height: 100%; object-fit: cover; border-radius: 12px;
}

/* Controls */
.book-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    width: 100%;
    max-width: 800px;
    background: rgba(255,255,255,0.85);
    padding: 15px 30px;
    border-radius: 40px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
}

.page-counter { font-size: 1.4rem; font-weight: 900; color: #2c3e50; min-width: 150px; text-align: center; }

.btn-3d {
    background: linear-gradient(180deg, var(--brand-blue), #00838f); color: white; border: 3px solid white; padding: 15px 40px;
    border-radius: 40px; font-size: 1.3rem; font-weight: 900; cursor: pointer; text-transform: uppercase;
    box-shadow: 0 8px 0 #006064, 0 10px 15px rgba(0, 188, 212, 0.4); transition: all 0.2s ease;
}
.btn-3d:active { transform: translateY(8px); box-shadow: 0 0 0 #006064; }
.btn-3d.disabled { opacity: 0.4; pointer-events: none; box-shadow: none; transform: translateY(8px); }

/* --- PREMIUM PAYWALL STYLES --- */
.paywall-overlay {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: rgba(255, 255, 255, 0.6);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 0;
    visibility: hidden;
    transition: all 0.4s ease;
}

.paywall-overlay.active {
    opacity: 1;
    visibility: visible;
}

.paywall-box {
    background: white;
    border-radius: 20px;
    padding: 40px;
    max-width: 400px;
    text-align: center;
    box-shadow: 0 20px 50px rgba(0,0,0,0.2);
    border: 4px solid var(--brand-pink);
    transform: translateY(20px);
    transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.paywall-overlay.active .paywall-box {
    transform: translateY(0);
}

.paywall-box .lock-icon {
    font-size: 4rem;
    margin-bottom: 10px;
}

.paywall-box h2 {
    font-size: 2rem;
    font-weight: 900;
    color: var(--brand-pink);
    text-transform: uppercase;
    margin-bottom: 15px;
}

.paywall-box p {
    font-size: 1.1rem;
    color: #475569;
    font-weight: bold;
    margin-bottom: 25px;
    line-height: 1.4;
}

.paywall-actions {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.btn-register {
    background: linear-gradient(180deg, var(--brand-pink), #c2185b);
    color: white;
    padding: 15px 30px;
    border-radius: 30px;
    font-size: 1.2rem;
    font-weight: 900;
    text-transform: uppercase;
    box-shadow: 0 6px 0 #880e4f, 0 10px 15px rgba(233, 30, 99, 0.3);
    transition: all 0.2s ease;
}
.btn-register:active { transform: translateY(6px); box-shadow: 0 0 0 #880e4f; }

.btn-login {
    background: white;
    color: var(--brand-blue);
    padding: 12px 30px;
    border-radius: 30px;
    font-size: 1.1rem;
    font-weight: 900;
    text-transform: uppercase;
    border: 3px solid var(--brand-blue);
    transition: all 0.2s ease;
}
.btn-login:hover { background: #f0fdfa; }

@media (max-width: 768px) {
    .reader-header { padding: 10px 15px; }
    .btn-nav { font-size: 0.9rem; padding: 10px 20px; }
    .book-controls { padding: 15px; gap: 10px; width: 100%; flex-wrap: wrap; }
    .btn-3d { padding: 15px 25px; font-size: 1.1rem; flex: 1; }
    .page-counter { width: 100%; order: -1; margin-bottom: 5px; font-size: 1.2rem; }
    .spine-line { width: 30px; }
    .paywall-box { padding: 30px 20px; width: 90%; }
    .paywall-box h2 { font-size: 1.6rem; }
    .paywall-box p { font-size: 1rem; }
}