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

:root {
    --primary: #4f46e5;
    --primary-dark: #4338ca;
    --secondary: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --dark: #1f2937;
    --gray: #6b7280;
    --light-gray: #e5e7eb;
    --lighter-gray: #f3f4f6;
    --white: #ffffff;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--lighter-gray);
    color: var(--dark);
    min-height: 100vh;
    line-height: 1.5;
}

/* Navigation */
nav {
    background: var(--dark);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

nav .nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav .logo {
    color: var(--white);
    font-size: 1.5rem;
    font-weight: 700;
    text-decoration: none;
}

nav .logo span {
    color: var(--secondary);
}

nav .nav-links {
    display: flex;
    gap: 1.5rem;
    list-style: none;
}

nav .nav-links a {
    color: var(--light-gray);
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    transition: all 0.2s;
}

nav .nav-links a:hover,
nav .nav-links a.active {
    background: var(--primary);
    color: var(--white);
}

/* Main Container */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Page Header */
.page-header {
    margin-bottom: 2rem;
}

.page-header h1 {
    font-size: 2rem;
    color: var(--dark);
    margin-bottom: 0.5rem;
}

.page-header p {
    color: var(--gray);
}

/* Cards */
.card {
    background: var(--white);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--light-gray);
}

.card-header h2 {
    font-size: 1.25rem;
    color: var(--dark);
}

.card-header h3 {
    font-size: 1.1rem;
    color: var(--dark);
}

/* Forms */
.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--light-gray);
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s;
}

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

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

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

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

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

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

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

.btn-success:hover {
    background: #059669;
}

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

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

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary);
    color: var(--primary);
}

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

/* Grid Layout */
.grid {
    display: grid;
    gap: 1.5rem;
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

/* Plan Cards */
.plan-card {
    background: var(--white);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--primary);
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.plan-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.plan-card .plan-meta {
    color: var(--gray);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.plan-card .exercises {
    list-style: none;
    margin-bottom: 1rem;
}

.plan-card .exercises li {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--lighter-gray);
    display: flex;
    justify-content: space-between;
}

.plan-card .exercises li:last-child {
    border-bottom: none;
}

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

/* Exercise List in Plan Builder */
.exercise-list {
    list-style: none;
}

.exercise-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem;
    background: var(--lighter-gray);
    border-radius: 8px;
    margin-bottom: 0.5rem;
}

.exercise-item .exercise-info {
    flex: 1;
}

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

.exercise-item .exercise-details {
    font-size: 0.875rem;
    color: var(--gray);
}

/* Log Entry */
.log-entry {
    background: var(--lighter-gray);
    border-radius: 8px;
    padding: 1rem;
    margin-bottom: 0.75rem;
}

.log-entry .log-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.log-entry .log-date {
    font-weight: 600;
    color: var(--primary);
}

.log-entry .log-exercise {
    font-weight: 600;
    color: var(--dark);
}

.log-entry .log-details {
    display: flex;
    gap: 1.5rem;
    color: var(--gray);
}

.log-entry .log-details span {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* Stats Cards */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--white);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    text-align: center;
}

.stat-card .stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary);
}

.stat-card .stat-label {
    color: var(--gray);
    font-size: 0.9rem;
    margin-top: 0.25rem;
}

.stat-card.success .stat-value {
    color: var(--secondary);
}

.stat-card.warning .stat-value {
    color: var(--warning);
}

/* Chart Container */
.chart-container {
    background: var(--white);
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.chart-container h3 {
    margin-bottom: 1rem;
    color: var(--dark);
}

.chart-container canvas {
    width: 100% !important;
    max-height: 400px;
}

.chart-controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.chart-controls select {
    padding: 0.5rem 1rem;
    border: 2px solid var(--light-gray);
    border-radius: 6px;
    font-size: 0.9rem;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--gray);
}

.empty-state h3 {
    margin-bottom: 0.5rem;
    color: var(--dark);
}

/* Tabs */
.tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid var(--light-gray);
    padding-bottom: 0.5rem;
}

.tab {
    padding: 0.75rem 1.5rem;
    border: none;
    background: transparent;
    font-size: 1rem;
    font-weight: 600;
    color: var(--gray);
    cursor: pointer;
    border-radius: 6px 6px 0 0;
    transition: all 0.2s;
}

.tab:hover {
    color: var(--primary);
    background: var(--lighter-gray);
}

.tab.active {
    color: var(--primary);
    background: var(--white);
    border: 2px solid var(--light-gray);
    border-bottom: 2px solid var(--white);
    margin-bottom: -2px;
}

/* Modal */
.modal-overlay {
    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;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
}

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

.modal {
    background: var(--white);
    border-radius: 12px;
    padding: 2rem;
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    transform: scale(0.9);
    transition: transform 0.3s;
}

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

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

.modal-header h2 {
    font-size: 1.5rem;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--gray);
}

.modal-close:hover {
    color: var(--dark);
}

/* Badge */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.badge-primary {
    background: rgba(79, 70, 229, 0.1);
    color: var(--primary);
}

.badge-success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--secondary);
}

/* Responsive */
@media (max-width: 768px) {
    nav .nav-container {
        flex-direction: column;
        gap: 1rem;
    }

    nav .nav-links {
        flex-wrap: wrap;
        justify-content: center;
    }

    main {
        padding: 1rem;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .chart-controls {
        flex-direction: column;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--lighter-gray);
}

::-webkit-scrollbar-thumb {
    background: var(--gray);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--dark);
}

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

.mb-1 {
    margin-bottom: 0.5rem;
}

.mb-2 {
    margin-bottom: 1rem;
}

.mb-3 {
    margin-bottom: 1.5rem;
}

.mt-2 {
    margin-top: 1rem;
}

.flex {
    display: flex;
}

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

.gap-1 {
    gap: 0.5rem;
}

.gap-2 {
    gap: 1rem;
}

/* User Info Header */
.user-info {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-left: auto;
}
.user-info span {
    font-weight: 600;
    color: var(--dark);
}