:root {
    --font-size-xs: 1.2rem;
    --font-size-sm: 1.4rem;
    --font-size-md: 1.6rem;
    --font-size-lg: 2rem;
    --font-size-xl: 3rem;
    --spacing-xxs: 0.6rem;
    --spacing-xs: 0.8rem;
    --spacing-sm: 1.6rem;
    --spacing-md: 2.4rem;
    --spacing-lg: 4rem;
    --icon-xs: 1rem;
    --icon-sm: 1.6rem; 
    --icon-md: 2rem;   
    --icon-lg: 3rem;  
    --icon-xl: 5rem;
    --icon-xxl: 7rem;
    --border-radius-xs: 0.8rem;
    --border-radius-sm: 1.2rem;
    --book-cover-width: 20rem;
    --book-cover-height: 30rem;
    --color-primary: #2783de;
    --color-secondary: #cbecff;
    --color-accent: #f5deb3;
    --color-to-read: #8a2be2;   
    --color-reading: #d35400;   
    --color-read: #2e8b57;    
}

html[data-color-mode="light"] {
    --color-text: #000;
    --color-subtext: #6a7080;
    --color-bg: #e9e9e9;
    --color-card: #ffffff;
}

html[data-color-mode="dark"] {
    --color-text: #fff;
    --color-subtext: #9ca8b4;
    --color-bg: #0d0f12;
    --color-card: #272e35;
}

body, 
html {
    font-family: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    font-size: 62.5%;
    background-color: var(--color-bg);
    min-height: 100vh;
    margin: 0;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
}

header .logo {
    display: flex;
}

header .logo svg {
    fill: var(--color-text);
    width: var(--icon-xxl);
    height: auto;
    margin-right: var(--spacing-xs);
}

header .logo h1 {
    font-size: var(--font-size-xl);
    color: var(--color-text);
    text-transform: uppercase;
    margin: 0;
}

header .logo p {
    font-size: var(--font-size-md);
    color: var(--color-subtext);
    margin: 0;
}

.header-btn {
    display: flex;
    gap: var(--spacing-sm)
}

#theme-toggle {
    font-size: var(--font-size-lg);
    background-color: var(--color-card);
    color: var(--color-text);
    border: none;
    border-radius: 100%;
    padding: var(--spacing-sm);
    cursor: pointer;
    overflow: hidden;
    text-align: center;
    transition: 0.5s;
}

.btn-add {
    font-size: var(--font-size-md);
    background-color: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: var(--border-radius-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    overflow: hidden;
    text-align: center;
    transition: 0.5s;
}

.btn-add:hover {
    transform: scale(1.1); 
}

.container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    padding: 0 var(--spacing-md);
}

ul {
    font-size: var(--font-size-md);
    list-style-type: none;
    display: flex;
    justify-content: left;
    gap: var(--spacing-sm);
    padding: 0 var(--spacing-md);
    margin: 0;
}

ul li {
    color: var(--color-subtext);
    display: flex;
    align-items: center;
    gap: var(--spacing-xxs);
    padding: var(--spacing-xxs) var(--spacing-xs);
    border-radius: var(--border-radius-xs);
    cursor: pointer;
    transition: 0.3s;
}

ul li:hover {
    background-color: var(--color-card);
}

ul li.active {
    background-color: var(--color-primary);
    color: #fff;
}

ul li svg {
    fill: var(--color-subtext);
    width: var(--icon-md);
    height: auto;
}

ul li.active svg {
    fill: #fff;
    
}

ul li p {
    margin: 0;
}

.books-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, var(--book-cover-width));
    gap: var(--spacing-md);
    padding: 0 var(--spacing-md);
}

.book {
    background-color: var(--color-card);
    border-radius: var(--border-radius-sm);
}

.book-cover {
    background-image: url(https://covers.openlibrary.org/b/id/15129220-L.jpg);
    background-position: center;
    background-size: cover;
    background-repeat: no-repeat;
    border-radius: var(--border-radius-sm) var(--border-radius-sm) 0 0;
    width: var(--book-cover-width);
    height: var(--book-cover-height);
    overflow: hidden;
}

.btn-action {
    display: flex;
    justify-content: space-between;
    margin: var(--spacing-xs);
}

.btn-status {
    font-size: var(--font-size-sm);
    color: #fff;
    border: none;
    border-radius: var(--border-radius-xs);
    padding: var(--spacing-xs);
    cursor: pointer;
    transition: 0.3s;
}

.btn-status:hover {
    opacity: 0.8;
}

.btn-status[data-book-status="to-read"] {
  background-color: var(--color-to-read);
}

.btn-status[data-book-status="reading"] {
  background-color: var(--color-reading);
}

.btn-status[data-book-status="read"] {
  background-color: var(--color-read);
}

.status-dropdown {
  position: relative;
}

.dropdown-menu {
    font-size: var(--font-size-sm);
    display: flex;
    flex-direction: column;
    position: absolute;
    gap: var(--spacing-xxs);
    top: 110%;
    left: 0;
    background: var(--color-bg);
    color: white;
    border-radius: var(--border-radius-xs);
    padding: 0;
    margin: 0;
    list-style: none;
    display: none;
    min-width: 9rem;
    z-index: 1;
}

.dropdown-menu li {
    margin: 0;
    padding: var(--spacing-xxs);
    cursor: pointer;
    white-space: nowrap;
}

.dropdown-menu li:hover {
    color: var(--color-bg);
  background: var(--color-subtext);
}

.status-dropdown.open .dropdown-menu {
  display: block;
}

.btn-remove {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--color-text);
    border: none;
    margin: 0;
    padding: 0;   
    border-radius: 100%;
    cursor: pointer;
    transition: 0.3s;
}

.btn-remove:hover {
    opacity: 0.8;
}

.btn-remove svg {
    fill: var(--color-card);
    width: var(--icon-lg);
    height: var(--icon-lg);
    transform: scale(1.3);
}

.book-details {
    font-size: var(--font-size-sm);
    padding: var(--spacing-sm);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xxs);
    overflow: hidden;
}

.book-details > * {
    color: var(--color-text);
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
    margin: 0;
}

.modal {
    position: fixed;        
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: none;         
    justify-content: center; 
    align-items: center;     
    background-color: rgba(0,0,0,0.5); 
}

.modal-header {
    display: flex;
    justify-content: space-between;
}

.modal-header h2 {
    font-size: var(--font-size-xl);
    color: var(--color-text);
    margin: 0;
}

.btn-close {
    font-size: var(--font-size-xl);
    font-weight: bold;
    color: var(--color-text);
    background: none;
    border: none;
    text-decoration: none;
    cursor: pointer;
}

.modal-content {
    background-color: var(--color-bg);
    border-radius: var(--border-radius-sm);
    padding: var(--spacing-md);
    width: 26%;
}

form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
}

form div {
    width: 100%;
}

label {
    font-size: var(--font-size-md);
    color: var(--color-subtext);
    display: block;
    margin-bottom: var(--spacing-xs);
}

input {
    font-size: var(--font-size-md);
    background-color: var(--color-card);
    color: var(--color-text);
    width: 100%;          
    box-sizing: border-box; 
    border: none;
    outline: 2px solid var(--color-subtext);
    border-radius: var(--border-radius-xs);
    padding: var(--spacing-xs);
    margin: 0;
}

input:focus {
    outline: 2px solid var(--color-primary);
}

select {
    font-size: var(--font-size-md);
    background-color: var(--color-card);
    color: var(--color-text);
    width: 100%;          
    box-sizing: border-box; 
    border: none;
    outline: 2px solid var(--color-subtext);
    border-radius: var(--border-radius-xs);
    padding: var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
}

form button {
    font-size: var(--font-size-md);
    background-color: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: var(--border-radius-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    height: auto;
    cursor: pointer;
    overflow: hidden;
    text-align: center;
    transition: 0.5s;
}