:root {
    --color-primary: #4CAF50;
    --color-primary-dark: #388E3C;
    --color-background: #FFFFFF;
    --color-surface: #F5F5F5;
    --color-surface-elevated: #FFFFFF;
    --color-text-primary: #212121;
    --color-text-secondary: #757575;
    --color-border: #E0E0E0;
    --color-danger: #F44336;
    --color-warning: #FF9800;

    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;

    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 24px;

    --border-radius: 12px;
    --border-radius-sm: 8px;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-background: #121212;
        --color-surface: #1E1E1E;
        --color-surface-elevated: #2D2D2D;
        --color-text-primary: #FFFFFF;
        --color-text-secondary: #B0B0B0;
        --color-border: #404040;
    }
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    background-color: var(--color-background);
    color: var(--color-text-primary);
    line-height: 1.5;
    min-height: 100vh;
}

.screen {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* Auth Screen */
.auth-container {
    max-width: 400px;
    margin: 0 auto;
    padding: var(--spacing-xl);
    padding-top: 80px;
}

.auth-container h1 {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    font-size: 32px;
    color: var(--color-primary);
}

.auth-form h2 {
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.auth-form form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.auth-form input {
    padding: var(--spacing-md);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    background: var(--color-surface);
    color: var(--color-text-primary);
}

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

.auth-form button {
    padding: var(--spacing-md);
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    cursor: pointer;
    transition: background var(--transition-fast);
}

.auth-form button:hover {
    background: var(--color-primary-dark);
}

.auth-switch {
    text-align: center;
    margin-top: var(--spacing-md);
    color: var(--color-text-secondary);
}

.auth-switch a {
    color: var(--color-primary);
    text-decoration: none;
}

.error {
    background: var(--color-danger);
    color: white;
    padding: var(--spacing-md);
    border-radius: var(--border-radius-sm);
    margin-top: var(--spacing-md);
    text-align: center;
}

/* Header */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

header h1 {
    font-size: var(--font-size-xl);
    color: var(--color-primary);
}

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

.icon-btn {
    background: none;
    border: none;
    padding: var(--spacing-sm);
    cursor: pointer;
    color: var(--color-text-secondary);
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
}

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

/* Sections */
.section {
    padding: var(--spacing-md);
}

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

.section h2 {
    font-size: var(--font-size-lg);
    color: var(--color-text-primary);
}

.timer {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-variant-numeric: tabular-nums;
}

/* Buttons */
.btn-large {
    width: 100%;
    padding: var(--spacing-lg);
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    font-size: var(--font-size-lg);
    cursor: pointer;
    transition: background var(--transition-fast);
}

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

.btn-primary {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    cursor: pointer;
    transition: background var(--transition-fast);
}

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

.btn-secondary {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-surface);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

.btn-danger {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-danger);
    color: white;
    border: none;
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    cursor: pointer;
    transition: opacity var(--transition-fast);
}

.btn-danger:hover {
    opacity: 0.9;
}

.btn-small {
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: var(--font-size-sm);
}

/* Exercise Input */
.exercise-input-container {
    position: relative;
    margin-bottom: var(--spacing-md);
}

#exercise-input {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    background: var(--color-surface);
    color: var(--color-text-primary);
}

#exercise-input:focus {
    outline: none;
    border-color: var(--color-primary);
}

.suggestions {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-surface-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-md);
    max-height: 200px;
    overflow-y: auto;
    z-index: 10;
}

.suggestion-item {
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    transition: background var(--transition-fast);
}

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

/* Workout Actions */
.workout-actions {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
}

/* Exercise Card */
.exercise-card {
    background: var(--color-surface);
    border-radius: var(--border-radius-sm);
    margin-bottom: var(--spacing-sm);
    overflow: hidden;
}

.exercise-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-surface-elevated);
}

.exercise-name {
    font-weight: 600;
}

.exercise-actions {
    display: flex;
    gap: var(--spacing-xs);
}

.sets-list {
    padding: var(--spacing-sm) var(--spacing-md);
}

.set-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xs) 0;
    border-bottom: 1px solid var(--color-border);
}

.set-row:last-child {
    border-bottom: none;
}

.set-info {
    display: flex;
    gap: var(--spacing-md);
}

.set-number {
    color: var(--color-text-secondary);
    min-width: 24px;
}

.set-weight, .set-reps {
    font-variant-numeric: tabular-nums;
}

.add-set-btn {
    width: 100%;
    padding: var(--spacing-sm);
    border: 1px dashed var(--color-border);
    background: transparent;
    color: var(--color-text-secondary);
    border-radius: 0;
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

/* Complex indicator */
.complex-indicator {
    background: var(--color-warning);
    color: white;
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 12px;
    margin-left: var(--spacing-sm);
}

/* Workout List */
.workout-item {
    background: var(--color-surface);
    border-radius: var(--border-radius-sm);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.workout-item:hover {
    background: var(--color-surface-elevated);
}

.workout-date {
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.workout-stats {
    display: flex;
    gap: var(--spacing-md);
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: var(--spacing-md);
}

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

.modal-small {
    max-width: 320px;
}

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

.modal-header h2 {
    font-size: var(--font-size-lg);
}

.close-btn {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--color-text-secondary);
    padding: var(--spacing-xs);
}

.modal-actions {
    padding: var(--spacing-md);
    border-top: 1px solid var(--color-border);
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
}

/* Forms */
.form-group {
    padding: var(--spacing-md);
}

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

.form-group input,
.form-group textarea {
    width: 100%;
    padding: var(--spacing-sm);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    background: var(--color-surface);
    color: var(--color-text-primary);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-primary);
}

.form-group textarea {
    resize: vertical;
    font-family: inherit;
}

.form-actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
}

/* Import */
#import-preview {
    padding: var(--spacing-md);
    background: var(--color-surface);
    max-height: 200px;
    overflow-y: auto;
}

#import-result {
    padding: var(--spacing-md);
}

.import-success {
    color: var(--color-primary);
}

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

/* Workout Detail */
#workout-detail-content {
    padding: var(--spacing-md);
}

/* Loading */
.loading {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--color-text-secondary);
}

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

/* Last Performance */
.last-performance {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
}

/* Settings Modal */
.settings-content {
    padding: var(--spacing-md);
}

.settings-content h3 {
    margin-bottom: var(--spacing-xs);
}

.settings-description {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-md);
}

.aliases-list {
    margin-bottom: var(--spacing-md);
    max-height: 300px;
    overflow-y: auto;
}

.alias-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    background: var(--color-surface);
    border-radius: var(--border-radius-sm);
    margin-bottom: var(--spacing-xs);
}

.alias-name {
    font-weight: 600;
    min-width: 80px;
}

.alias-arrow {
    color: var(--color-text-secondary);
}

.alias-canonical {
    flex: 1;
}

.alias-form {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.alias-form input {
    flex: 1;
    padding: var(--spacing-sm);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-base);
    background: var(--color-surface);
    color: var(--color-text-primary);
}

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

/* Responsive */
@media (max-width: 480px) {
    .auth-container {
        padding: var(--spacing-md);
        padding-top: 40px;
    }

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

    .alias-form {
        flex-direction: column;
    }

    .alias-form input {
        width: 100%;
    }
}