:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-main: #f8fafc;
    --bg-card: #ffffff;
    --text-main: #0f172a;
    --text-secondary: #64748b;
    --border: #e2e8f0;
    --success: #0891b2;
    --danger: #e11d48;
    --transition: all 0.5s cubic-bezier(0.23, 1, 0.32, 1);
    --liquid-shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    /* Glass for light mode */
    --glass: backdrop-filter: blur(12px) saturate(180%);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    min-height: 100vh;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
    position: relative;
    overflow-x: hidden;
}

/* View Transitions */
.view {
    transition: opacity 0.4s ease, transform 0.4s ease;
    width: 100%;
}

.view.hidden {
    display: none;
    opacity: 0;
    transform: translateX(20px);
}

.view.active {
    display: block;
    opacity: 1;
    transform: translateX(0);
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
    gap: 1.5rem;
}

.header-title-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.daily-stats-pill {
    background: linear-gradient(135deg, rgba(238, 119, 82, 0.2) 0%, rgba(231, 60, 126, 0.2) 50%, rgba(35, 166, 213, 0.2) 100%);
    border: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 0.5rem 1rem;
    border-radius: 2rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-main);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    animation: fadeIn 0.5s ease-out;
}

.pill-icon {
    font-size: 1.25rem;
}

.header-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1.5rem;
    margin-top: 1.5rem;
    flex-wrap: wrap;
}

.data-actions {
    display: flex;
    gap: 0.75rem;
}

.header-content {
    margin-bottom: 2rem;
}

.header-content h1 {
    font-size: 2.25rem;
    font-weight: 800;
    background: linear-gradient(135deg, #60a5fa, #22d3ee);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

.hero {
    margin-bottom: 2.5rem;
    overflow: hidden;
    border-radius: 2rem;
    height: 140px;
    border: 1px solid var(--border);
    position: relative;
}

.hero::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(to bottom, transparent, rgba(2, 6, 23, 0.4));
}

.hero-banner {
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0.6;
    filter: saturate(1.2) hue-rotate(180deg);
    transition: var(--transition);
}

.hero:hover .hero-banner {
    transform: scale(1.05);
    opacity: 1;
}


.header-content p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 0.75rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    font-family: inherit;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.btn-secondary {
    background-color: var(--border);
    color: var(--text-main);
}

.btn-secondary:hover {
    background-color: #475569;
}

.btn-icon {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: var(--transition);
}

.btn-icon:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--text-main);
}

/* Course Dashboard Layout - Row Based */
.course-grid {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.course-row {
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 1.5rem;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 2rem;
    transition: var(--transition);
    cursor: pointer;
    animation: fadeIn 0.8s ease-out;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
}

.course-row:hover {
    border-color: var(--primary);
    background-color: #ffffff;
    transform: translateY(-4px);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

.section-group {
    margin-bottom: 4rem;
}

.section-label {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-main);
}

.section-label::before {
    content: '';
    width: 4px;
    height: 24px;
    background: var(--primary);
    border-radius: 2px;
}

.completed-row {
    opacity: 0.8;
    border-style: solid;
    border-color: var(--success);
}

.completed-row:hover {
    opacity: 1;
    border-color: var(--success);
}

.row-info {
    flex: 0 0 250px;
    display: flex;
    flex-direction: column;
}

.row-progress-summary {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: 0.5rem;
}

.row-percentage {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
}

.row-count {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* Paginated Track */
.track-wrapper {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    align-items: center;
}

.lesson-track {
    display: grid;
    grid-template-columns: repeat(25, 1fr);
    gap: 0.4rem;
    width: 100%;
}

.pagination-controls {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.page-btn {
    width: 20px;
    height: 20px;
    border-radius: 4px;
    border: 1px solid var(--border);
    background: none;
    color: var(--text-secondary);
    font-size: 0.7rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.page-btn:hover {
    border-color: var(--primary);
    color: var(--text-main);
}

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

.lesson-box {
    width: 100%;
    aspect-ratio: 1;
    border-radius: 4px;
    border: 1px solid var(--border);
    background-color: rgba(255, 255, 255, 0.03);
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.5rem;
    color: transparent;
    cursor: pointer;
}

@media (max-width: 1200px) {
    .lesson-track {
        grid-template-columns: repeat(15, 1fr);
    }
}

@media (max-width: 900px) {
    .lesson-track {
        grid-template-columns: repeat(10, 1fr);
    }
}

.lesson-box:hover {
    border-color: var(--primary);
    transform: scale(1.1);
}

.lesson-box.checked {
    background-color: var(--primary);
    border-color: var(--primary);
    color: white;
}

.lesson-box.checked:hover {
    filter: brightness(1.2);
}

@media (max-width: 900px) {
    .course-row {
        flex-direction: column;
        align-items: stretch;
        gap: 1rem;
    }
    
    .row-info {
        flex: 1;
    }
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1.5rem;
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.card-meta {
    font-size: 0.8rem;
    color: var(--text-secondary);
    display: block;
}

.last-studied {
    font-size: 0.75rem;
    color: var(--primary);
    margin-top: 0.25rem;
    display: block;
    font-weight: 500;
}

.progress-container {
    margin-bottom: 1.5rem;
}

.progress-stats {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    margin-bottom: 0.75rem;
}

.percentage-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.count-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.progress-bar-bg {
    height: 10px;
    background-color: var(--border);
    border-radius: 5px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: linear-gradient(to right, #3b82f6, #06b6d4);
    border-radius: 5px;
    transition: width 0.8s cubic-bezier(0.19, 1, 0.22, 1);
    width: 0%;
    box-shadow: 0 0 15px rgba(59, 130, 246, 0.5);
}

/* Bulk Actions */
.bulk-actions {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
}

.text-btn {
    background: none;
    border: none;
    color: var(--primary);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    padding: 0;
    transition: var(--transition);
}

.text-btn:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Scrollable List */
.scrollable-list {
    max-height: 250px;
    overflow-y: auto;
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    background-color: rgba(0, 0, 0, 0.2);
    padding: 0.5rem;
}

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

.scrollable-list::-webkit-scrollbar-track {
    background: transparent;
}

.scrollable-list::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

.item-row {
    padding: 0.75rem;
    border-radius: 0.5rem;
    transition: var(--transition);
}

.item-row:hover {
    background-color: rgba(255, 255, 255, 0.05);
}

.item-row.checked {
    opacity: 0.7;
}

.item-row.checked .item-label {
    text-decoration: line-through;
    color: var(--text-secondary);
}

/* Custom Checkbox */
.checkbox-container {
    display: flex;
    align-items: center;
    position: relative;
    padding-left: 35px;
    cursor: pointer;
    font-size: 0.9rem;
    user-select: none;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: -2px;
    left: 0;
    height: 20px;
    width: 20px;
    background-color: #f1f5f9;
    border: 2px solid var(--border);
    border-radius: 6px;
    transition: var(--transition);
}

.checkbox-container:hover input ~ .checkmark {
    border-color: var(--primary);
}

.checkbox-container input:checked ~ .checkmark {
    background-color: var(--primary);
    border-color: var(--primary);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-container input:checked ~ .checkmark:after {
    display: block;
}

.checkbox-container .checkmark:after {
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.item-label {
    transition: var(--transition);
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.modal-overlay.show {
    opacity: 1;
    pointer-events: auto;
}

.modal {
    background-color: var(--bg-card);
    width: 90%;
    max-width: 500px;
    padding: 2rem;
    border-radius: 1.5rem;
    border: 1px solid var(--border);
    transform: scale(0.95);
    transition: transform 0.3s ease;
}

.modal-overlay.show .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

input {
    width: 100%;
    padding: 0.75rem 1rem;
    background-color: var(--bg-main);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    color: var(--text-main);
    font-family: inherit;
    font-size: 1rem;
    transition: var(--transition);
}

input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.2);
}

.modal-actions {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 2rem;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Detail View */
.detail-header {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 3rem;
    animation: slideDown 0.4s ease-out;
}

.back-btn {
    width: 48px;
    height: 48px;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 1rem;
    font-size: 1.25rem;
    color: var(--text-main);
}

.back-btn:hover {
    background-color: var(--primary);
    border-color: var(--primary);
}

.detail-header-content h1 {
    font-size: 2rem;
    margin-bottom: 0.25rem;
}

.detail-header-content p {
    color: var(--text-secondary);
}

.detail-progress-section {
    background-color: var(--bg-card);
    padding: 2rem;
    border-radius: 1.5rem;
    border: 1px solid var(--border);
    margin-bottom: 1.5rem;
    animation: fadeIn 0.5s ease-out;
}

/* Activity Chart */
.chart-section {
    background-color: var(--bg-card);
    padding: 1.5rem;
    border-radius: 1.5rem;
    border: 1px solid var(--border);
    margin-bottom: 1.5rem;
    animation: fadeIn 0.6s ease-out;
}

.section-title {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.1rem;
    margin-bottom: 1.5rem;
}

.bar-chart {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    height: 120px;
    padding-bottom: 2rem;
    position: relative;
    gap: 0.5rem;
}

.bar-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    height: 100%;
    justify-content: flex-end;
}

.bar-fill {
    width: 100%;
    max-width: 30px;
    background: linear-gradient(to top, var(--primary), #a855f7);
    border-radius: 6px 6px 2px 2px;
    min-height: 4px;
    height: 0%;
    transition: height 1s cubic-bezier(0.34, 1.56, 0.64, 1);
    position: relative;
}

.bar-fill:hover {
    filter: brightness(1.2);
    box-shadow: 0 0 15px rgba(99, 102, 241, 0.4);
}

.bar-fill::after {
    content: attr(data-value);
    position: absolute;
    top: -20px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--text-main);
}

.bar-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.detail-actions {
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
}

.detail-scrollable-list {
    max-height: 500px;
    overflow-y: auto;
    background-color: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 1.5rem;
    padding: 1.5rem;
    animation: slideUp 0.5s ease-out;
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.hidden {
    display: none !important;
}

.empty-state {
    grid-column: 1 / -1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 5rem 2rem;
    background-color: rgba(30, 41, 59, 0.5);
    border: 1px dashed var(--border);
    border-radius: 1.5rem;
    text-align: center;
}

.empty-state h3 {
    font-size: 1.5rem;
    color: var(--text-main);
    margin-bottom: 0.5rem;
}

.empty-state p {
    color: var(--text-secondary);
    max-width: 400px;
}

/* Toast */
.toast-container {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 2000;
}

.toast {
    background-color: var(--bg-card);
    color: var(--text-main);
    padding: 1rem 1.5rem;
    border-radius: 1rem;
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    border-left: 4px solid var(--primary);
    margin-top: 0.5rem;
    transform: translateX(120%);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.toast.show {
    transform: translateX(0);
}