:root {
    --bg-color: #f4f1ea;       
    --card-color: #ffffff;     
    --text-color: #2c3e50;
    --accent-color: #44ad59;   
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Georgia', serif; 
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.welcome-title {
    margin-bottom: 40px;
    font-size: 2.5rem;
    text-align: center;
}

.book-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    max-width: 800px;
    width: 100%;
}

.book-card {
    background: var(--card-color);
    padding: 40px 20px;
    text-align: center;
    border-radius: 8px;
    box-shadow: var(--shadow);
    text-decoration: none;
    color: var(--text-color);
    font-weight: bold;
    font-size: 1.2rem;
    border-left: 8px solid var(--accent-color); 
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.book-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.15);
}

.story-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    max-width: 600px;
    width: 100%;
}

.paper-page {
    background: var(--card-color);
    padding: 50px;
    border-radius: 4px;
    box-shadow: var(--shadow);
    width: 100%;
    min-height: 400px;
    position: relative;
    line-height: 1.8;
    font-size: 1.1rem;
    margin-bottom: 30px;
}

.paper-page::before {
    content: '';
    position: absolute;
    top: 0; left: 40px; width: 2px; height: 100%;
    background: rgba(68, 173, 89, 0.2); 
}

.navigation {
    display: flex;
    gap: 40px;
}

.nav-arrow {
    background: var(--card-color);
    border: none;
    color: var(--accent-color);
    font-size: 1.5rem;
    padding: 15px 25px;
    border-radius: 50px;
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: background 0.2s, transform 0.1s;
}

.nav-arrow:hover {
    background: var(--accent-color);
    color: white;
}

.nav-arrow:active {
    transform: scale(0.95);
}

.back-link {
    margin-top: 20px;
    color: #7f8c8d;
    text-decoration: none;
    font-size: 0.9rem;
}

.page-turn-next {
    animation: turnNext 0.4s ease-in-out;
}

.page-turn-prev {
    animation: turnPrev 0.4s ease-in-out;
}

@keyframes turnNext {
    0% { opacity: 1; transform: translateX(0) rotate(0deg); }
    40% { opacity: 0; transform: translateX(-100px) rotate(-5deg); }
    60% { opacity: 0; transform: translateX(100px) rotate(5deg); }
    100% { opacity: 1; transform: translateX(0) rotate(0deg); }
}

@keyframes turnPrev {
    0% { opacity: 1; transform: translateX(0) rotate(0deg); }
    40% { opacity: 0; transform: translateX(100px) rotate(5deg); }
    60% { opacity: 0; transform: translateX(-100px) rotate(-5deg); }
    100% { opacity: 1; transform: translateX(0) rotate(0deg); }
}

#story-text ul, #story-text ol {
    padding-left: 60px; 
    margin-top: 10px;
    margin-bottom: 10px;
}

#story-text li {
    margin-bottom: 5px;
}

.nav-arrow:disabled {
    opacity: 0.35;
    cursor: not-allowed;
    pointer-events: none; 
    background: var(--card-color); 
    color: var(--accent-color);
}