:root {
    --background-color: #121212;
    --surface-color: #1e1e1e;
    --primary-text-color: #e0e0e0;
    --secondary-text-color: #a0a0a0;
    --gold-accent: #c9a94e;
}

body {
    background-color: var(--background-color);
    color: var(--primary-text-color);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding-top: 70px; /* Space for sticky header */
}

.main-header {
    background-color: var(--surface-color);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 70px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-bottom: 1px solid #333;
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    max-width: 1200px;
    padding: 0 1rem;
}

.logo {
    height: 40px;
    width: auto;
}

.main-nav {
    display: flex;
    gap: 1.5rem;
}

.main-nav a {
    color: var(--secondary-text-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.main-nav a:hover {
    color: var(--gold-accent);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.header-actions .fa-search {
    font-size: 1.2rem;
    cursor: pointer;
    color: var(--secondary-text-color);
    transition: color 0.3s;
}
.header-actions .fa-search:hover {
    color: var(--gold-accent);
}

.login-btn {
    background-color: var(--gold-accent);
    color: #121212;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    font-weight: bold;
    cursor: pointer;
    transition: background-color 0.3s;
}

.login-btn:hover {
    background-color: #e6bf5a;
}

.hero-section {
    width: 100%;
    height: 40vh;
    background: linear-gradient(rgba(0,0,0,0.6), rgba(0,0,0,0.6)), url('https://placehold.co/1200x400/1a1a1a/333333?text=Hero+Banner') no-repeat center center;
    background-size: cover;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.hero-content h2 {
    font-size: 2.5rem;
    color: var(--gold-accent);
    margin: 0;
}

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

.shelf-title {
    font-size: 1.5rem;
    color: var(--gold-accent);
    border-bottom: 2px solid var(--gold-accent);
    display: inline-block;
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
}

.shelf-scroll {
    display: flex;
    overflow-x: auto;
    gap: 1rem;
    padding-bottom: 1rem; /* For scrollbar visibility */
    -ms-overflow-style: none;  /* IE and Edge */
    scrollbar-width: none;  /* Firefox */
}

.shelf-scroll::-webkit-scrollbar {
    display: none; /* Chrome, Safari, and Opera */
}

.book-card {
    flex: 0 0 auto;
    width: 150px;
    text-align: center;
}

.book-card img {
    width: 100%;
    height: 225px;
    object-fit: cover;
    border-radius: 5px;
    margin-bottom: 0.5rem;
}

.book-card h4 {
    margin: 0;
    font-size: 0.9rem;
    color: var(--primary-text-color);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Modal Styles */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
}

.modal-content {
    background-color: var(--surface-color);
    padding: 2rem;
    border-radius: 8px;
    text-align: center;
    border: 1px solid #333;
}

.modal-content h3 {
    color: var(--gold-accent);
    margin-top: 0;
}

.modal-content input {
    display: block;
    width: 80%;
    margin: 1rem auto;
    padding: 0.8rem;
    background-color: var(--background-color);
    border: 1px solid #444;
    color: var(--primary-text-color);
    border-radius: 5px;
    text-align: center;
    font-size: 1.2rem;
}

.modal-content button {
    background-color: var(--gold-accent);
    color: #121212;
    border: none;
    padding: 0.7rem 1.5rem;
    border-radius: 5px;
    font-weight: bold;
    cursor: pointer;
    margin: 0.5rem;
}

#2fa-cancel-btn {
    background-color: #555;
    color: #fff;
}