/* ===== Design System Tokens ===== */
:root {
    /* Colors - Energetic Fitness Theme */
    --color-primary: #FF6B35;
    --color-primary-dark: #E55A2B;
    --color-primary-light: #FF8F66;
    
    --color-secondary: #1A1A2E;
    --color-secondary-light: #2D2D44;
    
    --color-success: #00D26A;
    --color-warning: #FFB800;
    --color-error: #FF4757;
    
    --color-bg: #0F0F1A;
    --color-surface: #1A1A2E;
    --color-surface-elevated: #252540;
    
    --color-text-primary: #FFFFFF;
    --color-text-secondary: #A0A0B2;
    --color-text-muted: #6B6B80;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-md: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 3rem;
    --font-size-4xl: 4.5rem;
    
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --transition-slow: 350ms ease;
}

/* ===== Reset & Base ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

/* ===== App Container ===== */
.app {
    max-width: 430px;
    margin: 0 auto;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background: var(--color-bg);
}

/* ===== Header ===== */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-md) var(--space-lg);
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-surface-elevated);
}

.header-left {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.logo {
    font-size: var(--font-size-xl);
}

.header h1 {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
}

.btn-icon {
    background: none;
    border: none;
    font-size: var(--font-size-xl);
    cursor: pointer;
    padding: var(--space-sm);
    border-radius: var(--radius-md);
    transition: background var(--transition-fast);
}

.btn-icon:hover {
    background: var(--color-surface-elevated);
}

.btn-icon:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* ===== Main Content ===== */
.main {
    flex: 1;
    padding: var(--space-lg);
    display: flex;
    flex-direction: column;
    gap: var(--space-xl);
    overflow-y: auto;
    padding-bottom: 100px;
}

/* ===== Camera Preview ===== */
.camera-preview {
    position: relative;
    background: var(--color-surface);
    border-radius: var(--radius-xl);
    aspect-ratio: 4/3;
    overflow: hidden;
    border: 2px solid var(--color-surface-elevated);
}

.camera-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-surface) 0%, var(--color-secondary-light) 100%);
}

/* Skeleton Animation */
.pose-skeleton {
    position: relative;
    width: 80px;
    height: 120px;
    animation: skeleton-pulse 2s ease-in-out infinite;
}

@keyframes skeleton-pulse {
    0%, 100% { opacity: 0.6; transform: scale(1); }
    50% { opacity: 1; transform: scale(1.05); }
}

.skeleton-head {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 20px;
    background: var(--color-primary);
    border-radius: var(--radius-full);
}

.skeleton-body {
    position: absolute;
    top: 25px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 40px;
    background: var(--color-primary);
    border-radius: var(--radius-sm);
}

.skeleton-arm-left,
.skeleton-arm-right {
    position: absolute;
    top: 30px;
    width: 30px;
    height: 4px;
    background: var(--color-primary);
    border-radius: var(--radius-sm);
}

.skeleton-arm-left {
    right: 50%;
    transform-origin: right center;
    animation: arm-move 1s ease-in-out infinite;
}

.skeleton-arm-right {
    left: 50%;
    transform-origin: left center;
    animation: arm-move 1s ease-in-out infinite reverse;
}

@keyframes arm-move {
    0%, 100% { transform: rotate(-20deg); }
    50% { transform: rotate(20deg); }
}

.skeleton-leg-left,
.skeleton-leg-right {
    position: absolute;
    top: 65px;
    width: 4px;
    height: 45px;
    background: var(--color-primary);
    border-radius: var(--radius-sm);
}

.skeleton-leg-left {
    left: 30px;
}

.skeleton-leg-right {
    right: 30px;
}

.camera-label {
    margin-top: var(--space-lg);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.camera-label::before {
    content: '';
    width: 8px;
    height: 8px;
    background: var(--color-success);
    border-radius: var(--radius-full);
    animation: pulse 1.5s ease-in-out infinite;
}

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

.exercise-badge {
    position: absolute;
    bottom: var(--space-md);
    left: var(--space-md);
    right: var(--space-md);
    background: rgba(26, 26, 46, 0.9);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    padding: var(--space-sm) var(--space-md);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.exercise-icon {
    font-size: var(--font-size-xl);
}

.exercise-name {
    font-weight: var(--font-weight-semibold);
    flex: 1;
}

.confidence {
    font-size: var(--font-size-xs);
    color: var(--color-success);
    background: rgba(0, 210, 106, 0.1);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--radius-full);
}

/* ===== Counter Section ===== */
.counter-section {
    text-align: center;
}

.set-indicator {
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: var(--space-xs);
    margin-bottom: var(--space-md);
}

.set-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.set-number {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
}

.set-total {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.rep-counter {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xl);
}

.btn-adjust {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-full);
    border: 2px solid var(--color-surface-elevated);
    background: var(--color-surface);
    color: var(--color-text-primary);
    font-size: var(--font-size-2xl);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-adjust:hover {
    border-color: var(--color-primary);
    background: var(--color-surface-elevated);
}

.btn-adjust:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn-adjust:active {
    transform: scale(0.95);
}

.rep-display {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.rep-number {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    line-height: 1;
    color: var(--color-text-primary);
    transition: transform var(--transition-fast);
}

.rep-number.bump {
    transform: scale(1.1);
}

.rep-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    margin-top: var(--space-xs);
}

.target-info {
    margin-top: var(--space-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.target-value {
    color: var(--color-text-primary);
    font-weight: var(--font-weight-medium);
}

/* ===== Progress Ring ===== */
.progress-container {
    position: relative;
    width: 120px;
    height: 120px;
    margin: 0 auto;
}

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

.progress-bg {
    fill: none;
    stroke: var(--color-surface-elevated);
    stroke-width: 8;
}

.progress-bar {
    fill: none;
    stroke: var(--color-primary);
    stroke-width: 8;
    stroke-linecap: round;
    transition: stroke-dashoffset var(--transition-normal);
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
}

/* ===== Action Buttons ===== */
.actions {
    display: flex;
    gap: var(--space-md);
}

.btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-lg);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
}

.btn:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

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

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

.btn-primary:active {
    transform: scale(0.98);
}

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

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

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

/* ===== Bottom Navigation ===== */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    max-width: 430px;
    display: flex;
    background: var(--color-surface);
    border-top: 1px solid var(--color-surface-elevated);
    padding: var(--space-sm) 0;
    padding-bottom: calc(var(--space-sm) + env(safe-area-inset-bottom, 0));
}

.nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm);
    background: none;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
    transition: color var(--transition-fast);
}

.nav-item:hover {
    color: var(--color-text-secondary);
}

.nav-item.active {
    color: var(--color-primary);
}

.nav-item:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: -2px;
    border-radius: var(--radius-md);
}

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

.nav-label {
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-medium);
}

/* ===== Modal ===== */
.modal {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-lg);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
    z-index: 100;
}

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

.modal-content {
    background: var(--color-surface);
    border-radius: var(--radius-xl);
    padding: var(--space-xl);
    width: 100%;
    max-width: 360px;
    text-align: center;
    transform: scale(0.95);
    transition: transform var(--transition-normal);
}

.modal.active .modal-content {
    transform: scale(1);
}

.modal-content h2 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-lg);
}

.timer-display {
    margin-bottom: var(--space-lg);
}

.timer-value {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-primary);
}

.timer-presets {
    display: flex;
    gap: var(--space-sm);
    justify-content: center;
    margin-bottom: var(--space-xl);
}

.preset-btn {
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-full);
    background: var(--color-surface-elevated);
    border: 1px solid transparent;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

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

.preset-btn:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.modal-actions {
    display: flex;
    gap: var(--space-md);
}

/* ===== Loading State ===== */
.skeleton {
    background: linear-gradient(
        90deg,
        var(--color-surface-elevated) 25%,
        var(--color-secondary-light) 50%,
        var(--color-surface-elevated) 75%
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: var(--radius-md);
}

@keyframes shimmer {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* ===== Responsive ===== */
@media (max-width: 380px) {
    .rep-number {
        font-size: var(--font-size-3xl);
    }
    
    .btn-adjust {
        width: 48px;
        height: 48px;
    }
}