/* CSS Variables for theming */
:root {
    --primary-color: #007AFF;
    --secondary-color: #5856D6;
    --success-color: #34C759;
    --warning-color: #FF9500;
    --error-color: #FF3B30;
    --info-color: #5AC8FA;
    
    --text-primary: #000000;
    --text-secondary: #8E8E93;
    --text-tertiary: #C7C7CC;
    
    --background-primary: #FFFFFF;
    --background-secondary: #F2F2F7;
    --background-tertiary: #FFFFFF;
    --background-grouped: #F2F2F7;
    
    --border-color: #C6C6C8;
    --separator-color: #C6C6C8;
    
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 16px;
    --border-radius-xl: 20px;
    
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 20px;
    --spacing-xl: 24px;
    --spacing-xxl: 32px;
    
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-md: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 24px;
    --font-size-3xl: 32px;
    
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --text-primary: #FFFFFF;
        --text-secondary: #8E8E93;
        --text-tertiary: #48484A;
        
        --background-primary: #000000;
        --background-secondary: #1C1C1E;
        --background-tertiary: #2C2C2E;
        --background-grouped: #1C1C1E;
        
        --border-color: #38383A;
        --separator-color: #38383A;
    }
}

/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    line-height: 1.5;
    color: var(--text-primary);
    background-color: var(--background-grouped);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Layout */
#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Navigation */
.nav {
    background-color: var(--background-primary);
    border-bottom: 1px solid var(--separator-color);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 64px;
}

.nav-brand h1 {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary-color);
}

.nav-tabs {
    display: flex;
    gap: var(--spacing-sm);
}

.nav-tab {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    background: none;
    border: none;
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.nav-tab:hover {
    background-color: var(--background-secondary);
    color: var(--text-primary);
}

.nav-tab.active {
    background-color: var(--primary-color);
    color: white;
}

.nav-icon {
    font-size: var(--font-size-md);
}

/* Main content */
.main {
    flex: 1;
    padding: var(--spacing-xl) 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Tab content */
.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Hero section */
.hero {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

.hero h2 {
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.hero p {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Stats grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xxl);
}

.stat-card {
    background-color: var(--background-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: all 0.2s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.stat-icon {
    font-size: var(--font-size-2xl);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--background-secondary);
    border-radius: var(--border-radius-md);
}

.stat-content {
    flex: 1;
}

.stat-value {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    font-weight: var(--font-weight-medium);
}

/* Analytics stat cards */
.analytics-stat-card {
    background-color: var(--background-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

/* Action section */
.action-section {
    text-align: center;
    margin-bottom: var(--spacing-xxl);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    border: none;
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-medium);
    font-family: inherit;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
    min-height: 44px;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
    background-color: #0056CC;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover:not(:disabled) {
    background-color: var(--background-tertiary);
    transform: translateY(-1px);
}

.btn-large {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-lg);
    min-height: 56px;
}

.btn-icon {
    width: 44px;
    height: 44px;
    padding: 0;
    border-radius: 50%;
}

/* Cards */
.card {
    background-color: var(--background-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    margin-bottom: var(--spacing-md);
}

.current-session {
    border-left: 4px solid var(--success-color);
}

.session-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.session-icon {
    font-size: var(--font-size-lg);
}

.session-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--success-color);
}

.session-name {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

/* Section headers */
.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-xl);
}

.section-header h2 {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
}

/* Lists */
.workouts-list,
.exercises-list,
.history-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

/* Workout/Exercise items */
.workout-item,
.exercise-item,
.history-item {
    background-color: var(--background-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: all 0.2s ease;
}

.workout-item:hover,
.exercise-item:hover,
.history-item:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.item-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
}

.item-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
}

.item-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.item-meta {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-sm);
}

.item-tags {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
}

.tag {
    background-color: var(--primary-color);
    color: white;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-medium);
}

.tag.amrap {
    background-color: var(--info-color);
}

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

.tag.free {
    background-color: var(--warning-color);
}

/* Empty states */
.empty-state {
    text-align: center;
    padding: var(--spacing-xxl);
    color: var(--text-secondary);
}

.empty-icon {
    font-size: 48px;
    margin-bottom: var(--spacing-md);
}

.empty-state h3 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.empty-state p {
    margin-bottom: var(--spacing-lg);
}

/* Analytics */
.analytics-tabs {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    border-bottom: 1px solid var(--separator-color);
}

.analytics-tab {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-medium);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.analytics-tab:hover {
    color: var(--text-primary);
}

.analytics-tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.analytics-content {
    display: none;
}

.analytics-content.active {
    display: block;
}

.analytics-section {
    margin-bottom: var(--spacing-xxl);
}

.analytics-section h3 {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

/* Chart controls */
.chart-controls {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.chart-container {
    background-color: var(--background-primary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    height: 300px;
}

/* Forms */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.form-input,
.form-select {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-md);
    font-family: inherit;
    background-color: var(--background-primary);
    color: var(--text-primary);
    transition: border-color 0.2s ease;
}

.form-input:focus,
.form-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.1);
}

.exercise-selection {
    max-height: 200px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: var(--spacing-sm);
}

.exercise-checkbox {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-sm);
    transition: background-color 0.2s ease;
}

.exercise-checkbox:hover {
    background-color: var(--background-secondary);
}

.exercise-checkbox input[type="checkbox"] {
    margin: 0;
}

/* Modals */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    backdrop-filter: blur(4px);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
}

.modal-content {
    background-color: var(--background-primary);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    max-width: 500px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--separator-color);
}

.modal-header h3 {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: none;
    font-size: var(--font-size-xl);
    color: var(--text-secondary);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--border-radius-sm);
    transition: all 0.2s ease;
}

.modal-close:hover {
    background-color: var(--background-secondary);
    color: var(--text-primary);
}

.modal-body {
    padding: var(--spacing-lg);
}

.modal-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
    margin-top: var(--spacing-xl);
}

/* Active workout modal */
.active-workout-modal .modal-content {
    max-width: 600px;
    max-height: 80vh;
}

.active-workout-content {
    padding: 0;
}

.workout-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--separator-color);
    background-color: var(--background-secondary);
}

.workout-timer {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.timer-display {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    font-family: 'Courier New', monospace;
    color: var(--text-primary);
}

.workout-content {
    padding: var(--spacing-xl);
    text-align: center;
}

.exercise-info {
    margin-bottom: var(--spacing-xl);
}

.exercise-name {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.set-info {
    background-color: var(--background-secondary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.weight-display {
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

.planned-reps {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
}

.workout-actions {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    align-items: center;
}

/* Rest timer modal */
.rest-timer-modal .modal-content {
    max-width: 400px;
    text-align: center;
}

.rest-timer-content {
    padding: 0;
}

.rest-timer-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--separator-color);
}

.rest-timer-header h3 {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
}

.rest-timer-body {
    padding: var(--spacing-xl);
}

.rest-timer-body .timer-display {
    font-size: 64px;
    font-weight: var(--font-weight-bold);
    font-family: 'Courier New', monospace;
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
}

.timer-progress {
    margin-bottom: var(--spacing-xl);
}

.progress-ring {
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.progress-ring-circle {
    fill: none;
    stroke: var(--background-secondary);
    stroke-width: 8;
}

.progress-ring-circle:last-child {
    stroke: var(--primary-color);
    stroke-linecap: round;
    stroke-dasharray: 339.292;
    stroke-dashoffset: 339.292;
    transition: stroke-dashoffset 1s linear;
}

.rest-timer-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
}

/* Workout selection */
.workout-selection-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.workout-selection-item {
    background-color: var(--background-secondary);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    border: 1px solid var(--border-color);
    transition: all 0.2s ease;
}

.workout-selection-item:hover {
    background-color: var(--background-tertiary);
    transform: translateY(-1px);
}

.workout-selection-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
}

.workout-selection-name {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
}

.workout-selection-meta {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-sm);
}

/* iOS-specific optimizations */
@supports (-webkit-touch-callout: none) {
    /* iOS Safari specific styles */
    body {
        -webkit-touch-callout: none;
        -webkit-user-select: none;
        -webkit-tap-highlight-color: transparent;
    }
    
    input, textarea, select {
        -webkit-user-select: text;
    }
    
    /* Fix iOS viewport issues */
    .nav {
        padding-top: env(safe-area-inset-top);
    }
    
    .main {
        padding-bottom: env(safe-area-inset-bottom);
    }
    
    /* iOS scroll bounce fix */
    body {
        overscroll-behavior: none;
    }
}

/* PWA/Standalone app styles */
@media (display-mode: standalone) {
    .nav {
        padding-top: env(safe-area-inset-top, 20px);
    }
    
    .main {
        padding-bottom: env(safe-area-inset-bottom, 20px);
    }
}

/* iOS Safari bottom bar space */
@supports (padding-bottom: env(safe-area-inset-bottom)) {
    .modal-content {
        padding-bottom: calc(var(--spacing-lg) + env(safe-area-inset-bottom));
    }
    
    .workout-actions {
        padding-bottom: calc(var(--spacing-lg) + env(safe-area-inset-bottom));
    }
}

/* Responsive design */
@media (max-width: 768px) {
    .nav-content {
        flex-direction: column;
        gap: var(--spacing-md);
        padding: var(--spacing-md);
    }
    
    .nav-tabs {
        width: 100%;
        justify-content: space-between;
    }
    
    .nav-tab {
        flex: 1;
        justify-content: center;
    }
    
    .nav-tab span:last-child {
        display: none;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .section-header {
        flex-direction: column;
        gap: var(--spacing-md);
        align-items: stretch;
    }
    
    .chart-controls {
        flex-direction: column;
    }
    
    .modal {
        padding: var(--spacing-sm);
    }
    
    .modal-content {
        max-width: 100%;
    }
    
    .workout-actions {
        flex-direction: column;
    }
    
    .rest-timer-actions {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .hero h2 {
        font-size: var(--font-size-2xl);
    }
    
    .hero p {
        font-size: var(--font-size-md);
    }
    
    .stat-value {
        font-size: var(--font-size-xl);
    }
    
    .exercise-name {
        font-size: var(--font-size-xl);
    }
    
    .weight-display {
        font-size: var(--font-size-2xl);
    }
    
    .rest-timer-body .timer-display {
        font-size: 48px;
    }
}

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

.fade-in {
    animation: fadeIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        transform: translateX(-100%);
    }
    to {
        transform: translateX(0);
    }
}

.slide-in {
    animation: slideIn 0.3s ease-out;
}

/* Loading states */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Utility classes */
.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-xs); }
.mt-2 { margin-top: var(--spacing-sm); }
.mt-3 { margin-top: var(--spacing-md); }
.mt-4 { margin-top: var(--spacing-lg); }
.mt-5 { margin-top: var(--spacing-xl); }

.hidden {
    display: none !important;
}

.visible {
    display: block !important;
}

.flex {
    display: flex;
}

.flex-col {
    flex-direction: column;
}

.items-center {
    align-items: center;
}

.justify-center {
    justify-content: center;
}

.justify-between {
    justify-content: space-between;
}

.gap-1 { gap: var(--spacing-xs); }
.gap-2 { gap: var(--spacing-sm); }
.gap-3 { gap: var(--spacing-md); }
.gap-4 { gap: var(--spacing-lg); }
.gap-5 { gap: var(--spacing-xl); }