main.css

:root {
  --primary-bg: #1B1B2F;
  --secondary-bg: #2D1B3A;
  --accent-color: #C084FC;
  --accent-hover: #A855F7;
  --text-color: #E5E5E5;
  --text-muted: #9CA3AF;
  --border-color: #3F3F5F;
  --delete-color: #ff00009f;
  --delete-hover-color: #ff0000;
  
  --header-gradient: linear-gradient(90deg, #2D1B3A 0%, #3B2F4C 100%);
  --main-gradient: linear-gradient(180deg, #1B1B2F 0%, #151522 100%);
  --select-gradient: linear-gradient(135deg, #2D1B3A 0%, #3B2F4C 100%);
  --select-hover-gradient: linear-gradient(135deg, #3B2F4C 0%, #4A3F5F 100%);
  
  --shadow-light: 0 2px 4px rgba(0, 0, 0, 0.2);
  --shadow-medium: 0 4px 8px rgba(0, 0, 0, 0.4);
  --shadow-heavy: 0 8px 32px rgba(0, 0, 0, 0.4);
  --shadow-accent: 0 4px 8px rgba(192, 132, 252, 0.2);
  --shadow-accent-hover: 0 6px 12px rgba(192, 132, 252, 0.3);
  
  --spacing-xs: 0.3em;
  --spacing-sm: 0.5em;
  --spacing-md: 1em;
  --spacing-lg: 1.5em;
  --spacing-xl: 2em;
  
  --border-radius-sm: 0.3em;
  --border-radius-md: 0.5em;
  --border-radius-lg: 0.8em;
  --border-radius-xl: 1em;
  
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.6s ease;
  
  --image-width-default: 200px;
  --image-height-default: 300px;
  --image-width-fallback: 150px;
  --image-height-fallback: 200px;
  
  --scroll-amount: 40px;
}

html, body {
height: 100vh;
width: 100vw;
color: var(--text-color);
}

.container {
    display: grid;
    grid-template-columns: 4fr 1fr;
    grid-template-rows: 1fr 4fr;
    grid-template-areas: 
    "header header"
    "main side"
    "footer footer";
}

.header {
    grid-area: header;
    display: flex;
    justify-content: flex-start;
    align-items: center;
    height: 20vh;
    width: 100vw;
    background: var(--header-gradient);
    box-shadow: var(--shadow-medium);
}

.header-left {
    display: flex;
    
    height: 100%;
    width: 90%;
    justify-content: flex-start;
    align-items: center;
    margin-left: var(--spacing-lg);
}

.header h1 {
    font-size: 3rem;
    font-weight: bold;
    margin-left: var(--spacing-lg);
}

.header-right {
    display: flex;
    flex-direction: column;
    flex-wrap: wrap;
    height: 100%;
    width: 10%;
    justify-content: flex-start;
    align-items: center;
    margin-top: var(--spacing-xl);
    margin-right: var(--spacing-xl);
}

.header-right label {
    font-size: 1.2rem;
    font-weight: bold;
    margin-right: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.header-right select {
    background-color: var(--secondary-bg);
    color: var(--text-color);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    box-shadow: var(--shadow-light);
}

.header-right select option {
    background-color: var(--secondary-bg);
    color: var(--text-color);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
}

select option {
    background-color: var(--secondary-bg);
    color: var(--text-color);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
}

select {
    background-color: var(--secondary-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
}

.main {
    grid-area: main;
    height: 80vh;
    width: 80vw;
    background: var(--main-gradient);
}

.book-container {
    display: grid;
    margin-top: var(--spacing-lg);
    grid-template-columns: repeat(4, 1fr);
    justify-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    height: 100%;
    width: 100%;
}

.book-card {
    height: 23em;
    width: 18em;
    perspective: 1000px;
    position: relative;
}

.book-card:hover .book-card-inner {
    transform: rotateY(180deg);
}

.book-card-inner {
    background-color: var(--secondary-bg);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-medium);
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform var(--transition-slow);
    transform-style: preserve-3d;
}

.book-card-front {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.book-card-front img {
    width: var(--image-width-default);
    height: var(--image-height-default);
    object-fit: cover;
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-medium);
    margin-bottom: 15px;
}

.book-card-front img.default-cover {
    width: var(--image-width-fallback) !important;
    height: var(--image-height-fallback) !important;
    object-fit: cover !important;
    border-radius: var(--border-radius-xl) !important;
    box-shadow: var(--shadow-medium) !important;
}

.book-card-front h3 {
    margin: 0;
    font-size: 1.5em;
    font-weight: bold;
    color: var(--text-color);
    text-align: center;
}

.book-card-back {
    transform: rotateY(180deg);
    display: flex;
    flex-direction: column;
    width: 100%;
    height: 100%;
    font-size: 1.2em;
    font-weight: bold;
    color: var(--text-color);
    text-align: center;
}

.book-card-front, .book-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
}

.book-card-back-top {
    display: flex;
    justify-content: flex-end;
    align-items: flex-end;
    height: 10%;
    padding: var(--spacing-sm);
    border-bottom: 1px solid var(--border-color);
}

.book-card-back-top button {
    background-color: var(--accent-color);
    color: var(--primary-bg);
    border: none;
    border-radius: 50%;
    width: 1.5em;
    height: 1.5em;
    font-size: 1em;
    font-weight: bold;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.book-card-back-top button:hover {
    background-color: var(--accent-hover);
    transform: scale(1.1);
    box-shadow: var(--shadow-medium);
}

.book-card-back-bottom {
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr auto;
    height: 90%;
    padding: var(--spacing-md);
    gap: var(--spacing-sm);
    overflow: hidden;
}

.book-card-back-bottom .info {
    grid-column: 1;
    grid-row: 1;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--border-color);
}

.book-card-back-bottom .info p {
    margin: 0;
    font-size: 0.8em;
    line-height: 1.2;
    color: var(--text-color);
}

.book-card-back-bottom .summary {
    grid-column: 1;
    grid-row: 2;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    align-items: center;
    padding: var(--spacing-sm);
    background-color: rgba(45, 27, 58, 0.3);
    border-radius: var(--border-radius-md);
    border: 1px solid var(--border-color);
    overflow-y: auto;
    scroll-behavior: smooth;
    line-height: 1.4;
    scroll-padding: var(--spacing-xs);
}

.book-card-back-bottom .summary p {
    margin: 0;
    font-size: 0.9em;
    line-height: 1.4;
    text-align: center;
    color: var(--text-color);
}

.book-card-back-bottom .summary::-webkit-scrollbar {
    width: 4px;
}

.book-card-back-bottom .summary::-webkit-scrollbar-track {
    background: rgba(45, 27, 58, 0.2);
    border-radius: 2px;
}

.book-card-back-bottom .summary::-webkit-scrollbar-thumb {
    background: var(--accent-color);
    border-radius: 2px;
}

.book-card-back-bottom .select-container {
    grid-column: 1;
    grid-row: 3;
    display: flex;
    justify-content: center;
    align-items: center;
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

.book-card-back-bottom .select-container select {
    background: var(--select-gradient);
    color: var(--text-color);
    border: 2px solid var(--accent-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.9em;
    font-weight: bold;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-accent);
    min-width: 120px;
}

.book-card-back-bottom .select-container select:hover {
    background: var(--select-hover-gradient);
    border-color: var(--accent-hover);
    box-shadow: var(--shadow-accent-hover);
    transform: translateY(-2px);
}

.book-card-back-bottom .select-container select:focus {
    outline: none;
    border-color: var(--accent-hover);
    box-shadow: 0 0 0 3px rgba(192, 132, 252, 0.3);
}

.side {
    grid-area: side;
    height: 80vh;
    width: 20vw;
    background-color: var(--primary-bg);
    box-shadow: -2px 0 8px rgba(0, 0, 0, 0.4);
}

.elements {
    margin-top: var(--spacing-md);
    padding: var(--spacing-lg);
}

.information {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-md);
    border-top: 1px solid var(--text-color);
    border-bottom: 1px solid var(--text-color);
}

.information h2 {
    font-size: 1.5rem;
    font-weight: bold;
    margin-top: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.stat {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 80%;
    margin-bottom: var(--spacing-md);
}

.stat span {
    font-size: 1.2rem;
}

.addBooks {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0 var(--spacing-xl) var(--spacing-xl) var(--spacing-xl);
    border-bottom: 1px solid var(--text-color);
}

.addBooks button {
    background-color: var(--secondary-bg);
    color: var(--text-color);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 1.2rem;
    font-weight: bold;
    cursor: pointer;
    transition: background-color var(--transition-normal);
    box-shadow: var(--shadow-medium);
}

.addBooks button:hover {
    background-color: var(--accent-color);
    color: var(--primary-bg);
    transform: scale(1.05);
    box-shadow: var(--shadow-medium);
}

.addBooks button:active {
    transform: scale(0.95);
    box-shadow: var(--shadow-light);
}

.delete {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0 var(--spacing-xl) var(--spacing-xl) var(--spacing-xl);
    border-bottom: 1px solid var(--text-color);
}

.delete button {
    background-color: var(--delete-color);
    color: var(--text-color);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 1.2rem;
    font-weight: bold;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}


.theme-horror .delete button {
    color: #F3F4F6;
}

.delete button:hover {
    background-color: var(--delete-hover-color);
    transform: scale(1.05);
    box-shadow: var(--shadow-medium);
}


.delete button:active {
    transform: scale(0.95);
    box-shadow: var(--shadow-light);
}


#add-book-popup {
    transform: scale(0.5);
    opacity: 0;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
    pointer-events: none;
    height: 650px;
    width: 400px;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 1000;
    background-color: var(--primary-bg);
    border: 0.2em solid rgb(80, 79, 79);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-heavy);
}

.add-book-popup-content{
    display: flex;
    flex-direction: column;
    height: 100%;
    width: 100%;
    padding: 0;
}

.top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-md) var(--spacing-xl);
    border-bottom: 1px solid var(--text-color);
    background-color: var(--secondary-bg);
}

.top h3 {
    font-size: 1.8rem;
    font-weight: bold;
    margin: 0;
    color: var(--text-color);
}

.top button {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 2em;
    height: 2em;
    padding: 0;
    margin: 0;
    background: none;
    border: none;
    font-size: 1.8em;
    cursor: pointer;
    font-family: sans-serif;
    font-style: normal;
    color: var(--text-color);
    border-radius: 50%;
    transition: background-color var(--transition-normal);
}

.top button:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

#add-book-popup.active {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
    pointer-events: auto;
}

.bottom {
    flex: 1;
    padding: var(--spacing-xl);
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.add-book-popup-content form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    width: 100%;
}

.add-book-popup-content form input {
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    background-color: var(--secondary-bg);
    color: var(--text-color);
    font-size: 1rem;
    transition: border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.add-book-popup-content form textarea {
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    background-color: var(--secondary-bg);
    color: var(--text-color);
    font-size: 1rem;
    transition: border-color var(--transition-normal), box-shadow var(--transition-normal);
    resize: none;
    scroll-behavior: smooth;
    overflow-y: auto;
    line-height: 1.5;
    scroll-padding: var(--spacing-sm);
}

.add-book-popup-content form textarea::-webkit-scrollbar {
    width: 8px;
}

.add-book-popup-content form textarea::-webkit-scrollbar-track {
    background: rgba(45, 27, 58, 0.3);
    border-radius: 4px;
}

.add-book-popup-content form textarea::-webkit-scrollbar-thumb {
    background: var(--accent-color);
    border-radius: 4px;
    transition: background-color var(--transition-normal);
}

.add-book-popup-content form textarea::-webkit-scrollbar-thumb:hover {
    background: var(--accent-hover);
}

.add-book-popup-content form textarea:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px rgba(192, 132, 252, 0.2);
}

.add-book-popup-content form textarea::placeholder {
    color: var(--text-muted);
}

.add-book-popup-content form small {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: var(--spacing-sm);
}

.add-book-popup-content form input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px rgba(192, 132, 252, 0.2);
}

.add-book-popup-content form input::placeholder {
    color: var(--text-muted);
}

.add-book-popup-content form button {
    background-color: var(--accent-color);
    color: var(--primary-bg);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.add-book-popup-content form button:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

.add-book-popup-content form button:active {
    transform: translateY(0);
    box-shadow: var(--shadow-light);
}

.confirm-delete-popup {
    transform: scale(0.5);
    opacity: 0;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
    pointer-events: none;
    height: 200px;
    width: 400px;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 1000;
    background-color: var(--primary-bg);
    border: 0.2em solid rgb(80, 79, 79);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-heavy);
}

.confirm-delete-popup.active {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
    pointer-events: auto;
}

.confirm-delete-popup-content {
    display: flex;
    flex-direction: column;
    height: 100%;
    width: 100%;
    padding: 0;
}

.confirm-delete-popup-content .top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-md) var(--spacing-xl);
    border-bottom: 1px solid var(--text-color);
    background-color: var(--secondary-bg);
}

.confirm-delete-popup-content .top h3 {
    font-size: 1.5rem;
    font-weight: bold;
    margin: 0;
    color: var(--text-color);
}

.confirm-delete-popup-content .top button {
    background: none;
    border: none;
    font-size: 1.8em;
    cursor: pointer;
    font-family: sans-serif;
    font-style: normal;
    color: var(--text-color);
    border-radius: 50%;
    transition: background-color var(--transition-normal);
}

.confirm-delete-popup .top button:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

.confirm-delete-popup .top button:active {
    transform: scale(0.95);
    box-shadow: var(--shadow-light);
}

.confirm-delete-popup-content .bottom {
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-xl) var(--spacing-md) var(--spacing-xl);
    gap: var(--spacing-lg);
    border-top: 1px solid var(--text-color);
}

.confirm-delete-popup-content .bottom button {
    background-color: var(--accent-color);
    color: var(--primary-bg);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.confirm-delete-popup-content .bottom button:hover {
    background-color: var(--accent-hover);
    transform: scale(1.05);
    box-shadow: var(--shadow-medium);
}

.confirm-delete-popup-content .bottom button:active {
    transform: scale(0.95);
    box-shadow: var(--shadow-light);
}

.add-image-popup {
    transform: scale(0.5);
    opacity: 0;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
    pointer-events: none;
    height: 200px;
    width: 400px;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 1000;
    background-color: var(--primary-bg);
    border: 0.2em solid rgb(80, 79, 79);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-heavy);
}

.add-image-popup-content {
    display: flex;
    flex-direction: column;
    height: 100%;
    width: 100%;
    padding: 0;
}

.add-image-popup-content .top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-md) var(--spacing-xl);
}

.add-image-popup-content .top p {
    font-size: 1.2rem;
    font-weight: bold;
    margin: 0;
    color: var(--text-color);
}

.add-image-popup-content .top button {
    background: none;
    border: none;
    font-size: 1.8em;
    cursor: pointer;
    font-family: sans-serif;
}

.add-image-popup-content .bottom {
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-xl) var(--spacing-md) var(--spacing-xl);
    gap: var(--spacing-lg);
    border-top: 1px solid var(--text-color);
}

.add-image-popup-content .bottom button {
    background-color: var(--accent-color);
    color: var(--primary-bg);
    border: none;
    border-radius: var(--border-radius-md);
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.add-image-popup-content .bottom button:hover {
    background-color: var(--accent-hover);
    transform: scale(1.05);
    box-shadow: var(--shadow-medium);
}

.add-image-popup-content .bottom button:active {
    transform: scale(0.95);
    box-shadow: var(--shadow-light);
}

.add-image-popup.active {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
    pointer-events: auto;
}

.footer {
    grid-area: footer;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 10vh;
    width: 100vw;
    background-color: var(--primary-bg);
    border-top: 1px solid var(--text-color);
}

.footer p {
    font-size: 1rem;
    font-weight: bold;
    color: var(--text-color);
    margin: 0;
}