/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Primary Colors - School-friendly blues and greens */
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    
    /* Neutral Colors */
    --bg-color: #f8fafc;
    --surface-color: #ffffff;
    --surface-hover: #f1f5f9;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    
    /* Status Colors */
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    
    /* Priority Colors */
    --priority-high: #ef4444;
    --priority-medium: #f59e0b;
    --priority-low: #10b981;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    margin: 0;
    padding: 0;
}

.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
.app-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 1rem 0;
    box-shadow: var(--shadow-md);
    position: fixed !important;
    top: 0 !important;
    left: 0 !important;
    right: 0 !important;
    width: 100% !important;
    z-index: 9999 !important;
    transform: translateZ(0);
    -webkit-transform: translateZ(0);
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo i {
    font-size: 1.75rem;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin: 0;
}

.header-stats {
    display: flex;
    gap: 2rem;
}

.stat-item {
    text-align: center;
}

.stat-value {
    display: block;
    font-size: 1.25rem;
    font-weight: 600;
    line-height: 1.2;
}

.stat-label {
    font-size: 0.75rem;
    opacity: 0.9;
}

/* Navigation Styles */
.bottom-nav {
    background: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    padding: 0.75rem 0;
    display: flex;
    justify-content: space-around;
    position: fixed !important;
    top: 80px !important;
    left: 0 !important;
    right: 0 !important;
    width: 100% !important;
    z-index: 9998 !important;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    transform: translateZ(0);
    -webkit-transform: translateZ(0);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.5rem 1rem;
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition-fast);
    border-radius: var(--radius-md);
    min-width: 60px;
}

.nav-item:hover {
    background: var(--surface-hover);
    color: var(--text-primary);
}

.nav-item.active {
    color: var(--primary-color);
    background: rgba(37, 99, 235, 0.1);
}

.nav-item i {
    font-size: 1.25rem;
}

.nav-item span {
    font-size: 0.75rem;
    font-weight: 500;
}

/* Main Content */
.main-content {
    flex: 1;
    padding: 10rem 1rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.view {
    display: none;
}

.view.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

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

/* Timer View Styles */
.timer-container {
    text-align: center;
    max-width: 400px;
    margin: 0 auto;
}

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

.timer-header h2 {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

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

.timer-circle {
    position: relative;
    margin: 2rem 0;
    display: flex;
    justify-content: center;
}

.timer-progress {
    position: relative;
}

.progress-ring {
    transform: rotate(-90deg);
}

.progress-ring-bg {
    stroke: var(--border-color);
}

.progress-ring-fill {
    stroke: var(--primary-color);
    stroke-linecap: round;
    stroke-dasharray: 754;
    stroke-dashoffset: 754;
    transition: stroke-dashoffset var(--transition-normal);
}

.timer-display {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.timer-display .time {
    display: block;
    font-size: 3rem;
    font-weight: 300;
    color: var(--text-primary);
    line-height: 1;
}

.timer-display .time-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

.timer-controls {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin: 2rem 0;
}

.current-task {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-top: 2rem;
}

.current-task p {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

/* Button Styles */
.btn-primary, .btn-secondary, .btn-danger, .btn-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
    text-decoration: none;
    white-space: nowrap;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--surface-color);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

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

.btn-danger:hover {
    background: #dc2626;
}

.btn-link {
    background: none;
    color: var(--primary-color);
    padding: 0.5rem;
    font-size: 0.875rem;
}

.btn-link:hover {
    background: rgba(37, 99, 235, 0.1);
}

.full-width {
    width: 100%;
    justify-content: center;
}

/* Tasks View Styles */
.tasks-container {
    max-width: 600px;
    margin: 0 auto;
}

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

.tasks-header h2 {
    font-size: 1.75rem;
    font-weight: 600;
}

.task-input-container {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.task-input-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.task-input-group input, .task-input-group select {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    background: var(--surface-color);
    color: var(--text-primary);
}

.task-input-group input:focus, .task-input-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.task-input-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

.tasks-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.task-item {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: var(--transition-fast);
    cursor: pointer;
}

.task-item:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-sm);
}

.task-item.completed {
    opacity: 0.6;
    background: var(--surface-hover);
}

.task-item.completed .task-text {
    text-decoration: line-through;
}

.task-checkbox {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition-fast);
}

.task-checkbox.checked {
    background: var(--success-color);
    border-color: var(--success-color);
    color: white;
}

.task-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.task-text {
    font-weight: 500;
    color: var(--text-primary);
}

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

.task-priority {
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 500;
}

.task-priority.high {
    background: rgba(239, 68, 68, 0.1);
    color: var(--priority-high);
}

.task-priority.medium {
    background: rgba(245, 158, 11, 0.1);
    color: var(--priority-medium);
}

.task-priority.low {
    background: rgba(16, 185, 129, 0.1);
    color: var(--priority-low);
}

.task-actions {
    display: flex;
    gap: 0.5rem;
}

.task-action {
    padding: 0.375rem;
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition-fast);
}

.task-action:hover {
    background: var(--surface-hover);
    color: var(--text-primary);
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

/* Stats View Styles */
.stats-container {
    max-width: 800px;
    margin: 0 auto;
}

.stats-container h2 {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 2rem;
    text-align: center;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: var(--transition-fast);
}

.stat-card:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
}

.stat-icon {
    width: 48px;
    height: 48px;
    background: rgba(37, 99, 235, 0.1);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    font-size: 1.25rem;
}

.stat-content {
    flex: 1;
}

.stat-number {
    display: block;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.2;
}

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

.achievement-section h3, .weekly-chart h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 1rem;
    margin-bottom: 3rem;
}

.achievement-item {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1rem;
    text-align: center;
    transition: var(--transition-fast);
}

.achievement-item.unlocked {
    border-color: var(--accent-color);
    background: rgba(245, 158, 11, 0.05);
}

.achievement-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    opacity: 0.3;
}

.achievement-item.unlocked .achievement-icon {
    opacity: 1;
    color: var(--accent-color);
}

.achievement-name {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.achievement-desc {
    font-size: 0.625rem;
    color: var(--text-secondary);
}

.chart-container {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    text-align: center;
}

/* Settings View Styles */
.settings-container {
    max-width: 600px;
    margin: 0 auto;
}

.settings-container h2 {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 2rem;
    text-align: center;
}

.settings-group {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.settings-group h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.setting-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
}

.setting-item:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.setting-item label {
    font-weight: 500;
    color: var(--text-primary);
}

.setting-item input[type="range"] {
    flex: 1;
    margin: 0 1rem;
    accent-color: var(--primary-color);
}

.setting-value {
    min-width: 40px;
    text-align: center;
    font-weight: 500;
    color: var(--primary-color);
}

/* Toggle Switch */
.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 24px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--border-color);
    transition: var(--transition-normal);
    border-radius: 24px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: var(--transition-normal);
    border-radius: 50%;
}

input:checked + .slider {
    background-color: var(--primary-color);
}

input:checked + .slider:before {
    transform: translateX(26px);
}

.setting-info {
    flex: 1;
    margin-left: 1rem;
}

.setting-info span {
    display: block;
    font-weight: 500;
    color: var(--text-primary);
}

.setting-info small {
    color: var(--text-secondary);
    font-size: 0.75rem;
}

.about-info {
    text-align: center;
    color: var(--text-secondary);
}

.about-info p {
    margin-bottom: 0.5rem;
}

.about-info strong {
    color: var(--text-primary);
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    animation: fadeIn 0.3s ease;
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal-content {
    background: var(--surface-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    max-width: 400px;
    width: 100%;
    text-align: center;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { transform: translateY(-50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.modal-content h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.modal-content p {
    margin-bottom: 2rem;
    color: var(--text-secondary);
}

.modal-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        padding: 0 1rem;
    }
    
    .header-stats {
        gap: 1rem;
    }
    
    .stat-value {
        font-size: 1rem;
    }
    
    .main-content {
        padding: 9rem 1rem 2rem;
    }
    
    .timer-display .time {
        font-size: 2.5rem;
    }
    
    .timer-controls {
        flex-wrap: wrap;
        gap: 0.75rem;
    }
    
    .tasks-header {
        flex-direction: column;
        gap: 1rem;
        align-items: stretch;
    }
    
    .task-input-actions {
        flex-direction: column;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .achievements-grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    }
    
    .modal-actions {
        flex-direction: column;
    }
    
    .setting-item {
        flex-direction: column;
        align-items: stretch;
        gap: 0.5rem;
    }
    
    .setting-item input[type="range"] {
        margin: 0.5rem 0;
    }
}

@media (max-width: 480px) {
    .logo h1 {
        font-size: 1.25rem;
    }
    
    .timer-display .time {
        font-size: 2rem;
    }
    
    .progress-ring {
        width: 240px;
        height: 240px;
    }
    
    .progress-ring circle {
        cx: 120;
        cy: 120;
        r: 100;
    }
    
    .nav-item {
        padding: 0.5rem 0.75rem;
        min-width: 50px;
    }
    
    .nav-item span {
        font-size: 0.625rem;
    }
}

/* Animation Classes */
.pulse {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.bounce {
    animation: bounce 0.5s ease;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.shake {
    animation: shake 0.5s ease;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

/* Focus styles for accessibility */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

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

/* Print styles */
@media print {
    .bottom-nav, .timer-controls, .modal {
        display: none !important;
    }
    
    .main-content {
        padding-bottom: 1rem;
    }
}