:root {
    --primary-color: #4361ee;
    --secondary-color: #3a0ca3;
    --success-color: #4cc9f0;
    --complete-color: #4ade80;
    --danger-color: #f72585;
    --light-color: #f8f9fa;
    --dark-color: #212529;
    --gray-color: #6c757d;
    --border-radius: 12px;
    --box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    
    /* Light theme variables (default) */
    --bg-color: #f5f7ff;
    --card-bg: #ffffff;
    --text-color: #212529;
    --border-color: #e0e0e0;
    --input-bg: #ffffff;
    --item-bg: #f9f9ff;
    --item-hover: #f0f2ff;
    --complete-item-bg: #f0fff4;
    --complete-item-hover: #e6f9ec;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

/* Dark theme variables */
.dark-theme {
    --bg-color: #121212;
    --card-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --border-color: #333333;
    --input-bg: #2d2d2d;
    --item-bg: #252525;
    --item-hover: #2a2a2a;
    --complete-item-bg: #1a2a1a;
    --complete-item-hover: #1e321e;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --gray-color: #a0a0a0;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    min-height: 100vh;
    transition: var(--transition);
}

.container {
    max-width: 1400px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 30px;
    padding: 20px;
}

h1 {
    color: var(--primary-color);
    font-size: 2.8rem;
    margin-bottom: 10px;
    font-weight: 800;
}

.subtitle {
    color: var(--gray-color);
    font-size: 1.2rem;
    margin-bottom: 25px;
}

.theme-toggle-container {
    position: absolute;
    top: 30px;
    right: 30px;
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    font-size: 1.5rem;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    background-color: var(--card-bg);
    box-shadow: 0 4px 12px var(--shadow-color);
}

.theme-toggle:hover {
    transform: scale(1.1);
    background-color: var(--primary-color);
    color: white;
}

.theme-toggle .fa-sun {
    display: none;
}

.dark-theme .theme-toggle .fa-sun {
    display: block;
}

.dark-theme .theme-toggle .fa-moon {
    display: none;
}

.app-controls {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 15px;
    margin-bottom: 30px;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: var(--transition);
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--secondary-color);
    transform: translateY(-3px);
}

.btn-success {
    background-color: var(--success-color);
    color: white;
}

.btn-success:hover {
    opacity: 0.9;
    transform: translateY(-3px);
}

.btn-complete {
    background-color: var(--complete-color);
    color: white;
}

.btn-complete:hover {
    opacity: 0.9;
    transform: translateY(-3px);
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
}

.btn-danger:hover {
    opacity: 0.9;
    transform: translateY(-3px);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-outline:hover {
    background-color: rgba(67, 97, 238, 0.1);
    transform: translateY(-3px);
}

.lists-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 25px;
    margin-top: 20px;
}

.list-card {
    background-color: var(--card-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 25px;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    height: 100%;
    border: 1px solid var(--border-color);
}

.list-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 28px var(--shadow-color);
}

.list-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--border-color);
}

.list-title {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--primary-color);
    flex-grow: 1;
    cursor: pointer;
    padding: 5px 10px;
    border-radius: 6px;
    transition: var(--transition);
}

.list-title:hover {
    background-color: rgba(67, 97, 238, 0.08);
}

.list-title-input {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    border-radius: 6px;
    padding: 5px 10px;
    width: 100%;
    background-color: var(--input-bg);
    color: var(--text-color);
}

.list-actions {
    display: flex;
    gap: 10px;
}

.icon-btn {
    background: none;
    border: none;
    color: var(--gray-color);
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    background-color: rgba(255, 255, 255, 0.05);
    color: var(--text-color);
}

.delete-list-btn {
    color: var(--danger-color);
}

.delete-list-btn:hover {
    background-color: rgba(247, 37, 133, 0.1);
}

.add-item-form {
    display: flex;
    gap: 10px;
    margin-bottom: 25px;
}

.item-input {
    flex-grow: 1;
    padding: 12px 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    background-color: var(--input-bg);
    color: var(--text-color);
}

.item-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.items-list {
    flex-grow: 1;
    list-style-type: none;
    margin-bottom: 20px;
    max-height: 300px;
    overflow-y: auto;
    padding-right: 5px;
}

.items-list::-webkit-scrollbar {
    width: 6px;
}

.items-list::-webkit-scrollbar-thumb {
    background-color: var(--gray-color);
    border-radius: 10px;
}

.list-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    background-color: var(--item-bg);
    border-radius: 8px;
    margin-bottom: 10px;
    transition: var(--transition);
}

.list-item:hover {
    background-color: var(--item-hover);
}

.list-item.complete {
    background-color: var(--complete-item-bg);
    opacity: 0.9;
}

.list-item.complete:hover {
    background-color: var(--complete-item-hover);
}

.item-content {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-grow: 1;
}

.item-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--complete-color);
}

.item-text {
    flex-grow: 1;
    cursor: pointer;
    padding: 5px;
    border-radius: 4px;
    transition: var(--transition);
    word-break: break-word;
}

.item-text:hover {
    background-color: rgba(67, 97, 238, 0.08);
}

.item-text.complete {
    text-decoration: line-through;
    color: var(--gray-color);
    opacity: 0.8;
}

.item-text-input {
    flex-grow: 1;
    border: 2px solid var(--primary-color);
    border-radius: 6px;
    padding: 5px 10px;
    font-size: 1rem;
    background-color: var(--input-bg);
    color: var(--text-color);
}

.item-actions {
    display: flex;
    gap: 8px;
}

.complete-btn {
    color: var(--complete-color);
}

.complete-btn:hover {
    background-color: rgba(74, 222, 128, 0.1);
}

.incomplete-btn {
    color: var(--gray-color);
}

.incomplete-btn:hover {
    background-color: rgba(108, 117, 125, 0.1);
}

.empty-list-message {
    text-align: center;
    color: var(--gray-color);
    font-style: italic;
    padding: 20px;
}

.list-stats {
    display: flex;
    justify-content: space-between;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
    font-size: 0.9rem;
    color: var(--gray-color);
}

.complete-count {
    color: var(--complete-color);
    font-weight: 600;
}

.total-count {
    color: var(--primary-color);
    font-weight: 600;
}

.notification {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 15px 25px;
    border-radius: var(--border-radius);
    background-color: var(--primary-color);
    color: white;
    font-weight: 600;
    box-shadow: var(--box-shadow);
    transform: translateY(100px);
    opacity: 0;
    transition: var(--transition);
    z-index: 1000;
}

.notification.show {
    transform: translateY(0);
    opacity: 1;
}

.notification.success {
    background-color: var(--success-color);
}

.notification.complete {
    background-color: var(--complete-color);
}

.notification.error {
    background-color: var(--danger-color);
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background-color: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 30px;
    max-width: 500px;
    width: 90%;
    box-shadow: var(--box-shadow);
    transform: translateY(-20px);
    transition: var(--transition);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.modal.active .modal-content {
    transform: translateY(0);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.modal-title {
    font-size: 1.5rem;
    color: var(--text-color);
}

.modal-body {
    margin-bottom: 25px;
}

.modal-textarea {
    width: 100%;
    height: 200px;
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-family: monospace;
    font-size: 0.9rem;
    resize: vertical;
    background-color: var(--input-bg);
    color: var(--text-color);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 15px;
}

.danger-modal .modal-content {
    border-top: 5px solid var(--danger-color);
}

.danger-modal .modal-title {
    color: var(--danger-color);
}

@media (max-width: 768px) {
    .lists-container {
        grid-template-columns: 1fr;
    }
    
    .app-controls {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    h1 {
        font-size: 2.2rem;
    }
    
    .item-actions {
        flex-direction: column;
    }
    
    .theme-toggle-container {
        position: relative;
        top: 0;
        right: 0;
        margin-bottom: 20px;
        display: flex;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .list-card {
        padding: 20px;
    }
    
    .add-item-form {
        flex-direction: column;
    }
    
    .list-actions {
        flex-wrap: wrap;
    }
    
    .item-content {
        gap: 8px;
    }
}