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

:root {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --text-primary: #c9d1d9;
    --text-secondary: #8b949e;
    --border-color: #30363d;
    --accent-color: #238636;
    --danger-color: #da3633;
    --warning-color: #d29922;
    --level-0: #161b22;
    --level-1: #0e4429;
    --level-2: #006d32;
    --level-3: #26a641;
    --level-4: #39d353;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans', Helvetica, Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
}

.app {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    padding: 20px 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 30px;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

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

.header h1 {
    font-size: 2rem;
    margin-bottom: 4px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 8px 12px;
    border-radius: 6px;
    transition: all 0.2s;
}

.nav-link:hover {
    color: var(--text-primary);
    background: var(--bg-tertiary);
}

.btn-small {
    padding: 8px 16px;
    font-size: 0.875rem;
}

/* Auth Prompt */
.auth-prompt {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 48px;
    text-align: center;
    margin: 40px auto;
    max-width: 500px;
}

.auth-prompt h2 {
    margin-bottom: 12px;
    font-size: 1.5rem;
}

.auth-prompt p {
    color: var(--text-secondary);
    margin-bottom: 24px;
}

.auth-prompt-buttons {
    display: flex;
    gap: 12px;
    justify-content: center;
}

.auth-prompt-buttons .btn {
    padding: 12px 24px;
}

/* Stats Overview */
.stats-overview {
    display: flex;
    gap: 20px;
    justify-content: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.stat-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px 40px;
    text-align: center;
    min-width: 150px;
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: bold;
    color: var(--accent-color);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Today Section */
.today-section {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 25px;
    margin-bottom: 30px;
}

.today-section h2 {
    margin-bottom: 20px;
    font-size: 1.3rem;
    color: var(--text-primary);
}

.today-section h2 span {
    color: var(--text-secondary);
    font-weight: normal;
}

.today-habits {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.today-habit-btn {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1rem;
    color: var(--text-primary);
}

.today-habit-btn:hover {
    border-color: var(--text-secondary);
    transform: translateY(-2px);
}

.today-habit-btn.completed {
    border-color: var(--accent-color);
    background: rgba(35, 134, 54, 0.2);
}

.today-habit-btn.completed .habit-check {
    background: var(--accent-color);
    color: white;
}

.today-habit-btn .habit-check {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    transition: all 0.2s ease;
}

.today-habit-btn .habit-name {
    font-weight: 500;
}

.today-habit-btn .streak-badge {
    background: var(--bg-primary);
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.today-habit-btn.completed .streak-badge {
    background: var(--accent-color);
    color: white;
}

.today-empty {
    color: var(--text-secondary);
    font-style: italic;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

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

.btn-primary:hover {
    background: #2ea043;
}

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

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

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

.btn-danger:hover {
    background: #f85149;
}

.btn-small {
    padding: 5px 10px;
    font-size: 0.85rem;
}

/* Add Habit Section */
.add-habit-section {
    margin-bottom: 30px;
}

.add-habit-form {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 25px;
    margin-top: 15px;
}

.add-habit-form h3 {
    margin-bottom: 20px;
    color: var(--text-primary);
}

/* Form Styles */
.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.form-group input[type="text"],
.form-group input[type="number"],
.form-group select {
    width: 100%;
    padding: 10px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 1rem;
}

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

.form-group input[type="color"] {
    width: 60px;
    height: 40px;
    padding: 0;
    border: none;
    cursor: pointer;
}

.form-row {
    display: flex;
    gap: 20px;
}

.form-row .form-group {
    flex: 1;
}

.form-actions {
    display: flex;
    gap: 10px;
    margin-top: 20px;
}

/* Habit Card */
.habit-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
}

.habit-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
}

.habit-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

.habit-icon {
    font-size: 2rem;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    border-radius: 8px;
}

.habit-details h3 {
    font-size: 1.2rem;
    margin-bottom: 5px;
}

.habit-details p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.habit-actions {
    display: flex;
    gap: 8px;
}

/* Contribution Grid */
.contribution-grid-container {
    overflow-x: auto;
    padding: 10px 0;
}

.contribution-grid {
    display: flex;
    gap: 3px;
}

.week-column {
    display: flex;
    flex-direction: column;
    gap: 3px;
}

.day-cell {
    width: 12px;
    height: 12px;
    border-radius: 2px;
    cursor: pointer;
    transition: all 0.1s ease;
}

.day-cell:hover {
    transform: scale(1.2);
    outline: 1px solid var(--text-secondary);
}

.day-cell[data-level="0"] {
    background: var(--level-0);
    border: 1px solid var(--border-color);
}

.day-cell[data-level="1"] {
    background: var(--level-1);
}

.day-cell[data-level="2"] {
    background: var(--level-2);
}

.day-cell[data-level="3"] {
    background: var(--level-3);
}

.day-cell[data-level="4"] {
    background: var(--level-4);
}

/* Custom color support */
.day-cell[data-level="1"][style*="--habit-color"] {
    background: color-mix(in srgb, var(--habit-color) 25%, var(--level-0));
}
.day-cell[data-level="2"][style*="--habit-color"] {
    background: color-mix(in srgb, var(--habit-color) 50%, var(--level-0));
}
.day-cell[data-level="3"][style*="--habit-color"] {
    background: color-mix(in srgb, var(--habit-color) 75%, var(--level-0));
}
.day-cell[data-level="4"][style*="--habit-color"] {
    background: var(--habit-color);
}

/* Month Labels */
.grid-wrapper {
    position: relative;
}

.month-labels {
    display: flex;
    margin-bottom: 5px;
    font-size: 10px;
    color: var(--text-secondary);
    padding-left: 30px;
}

.month-label {
    min-width: 45px;
}

.day-labels {
    display: flex;
    flex-direction: column;
    gap: 3px;
    position: absolute;
    left: 0;
    top: 20px;
    font-size: 10px;
    color: var(--text-secondary);
}

.day-labels span {
    height: 12px;
    display: flex;
    align-items: center;
}

.contribution-grid-wrapper {
    display: flex;
    padding-left: 30px;
}

/* Habit Stats */
.habit-stats {
    display: flex;
    gap: 20px;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
    flex-wrap: wrap;
}

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

.habit-stat-value {
    font-size: 1.2rem;
    font-weight: bold;
}

.habit-stat-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* Goals */
.habit-goals {
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

.habit-goals h4 {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 10px;
}

.goal-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-tertiary);
    padding: 10px;
    border-radius: 4px;
    margin-bottom: 8px;
}

.goal-info {
    flex: 1;
}

.goal-progress {
    width: 100px;
    height: 6px;
    background: var(--border-color);
    border-radius: 3px;
    overflow: hidden;
    margin-top: 5px;
}

.goal-progress-bar {
    height: 100%;
    background: var(--accent-color);
    transition: width 0.3s ease;
}

.goal-progress-bar.complete {
    background: var(--level-4);
}

/* Legend */
.contribution-legend {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    gap: 5px;
    margin-top: 10px;
    font-size: 11px;
    color: var(--text-secondary);
}

.legend-box {
    width: 12px;
    height: 12px;
    border-radius: 2px;
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 25px;
    width: 90%;
    max-width: 450px;
    position: relative;
}

.modal-content h3 {
    margin-bottom: 20px;
}

.close-modal {
    position: absolute;
    top: 15px;
    right: 20px;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
}

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

/* Tooltip */
.tooltip {
    position: fixed;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    padding: 8px 12px;
    border-radius: 4px;
    font-size: 12px;
    pointer-events: none;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

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

.tooltip span {
    color: var(--text-secondary);
}

/* Loading */
.loading {
    text-align: center;
    padding: 40px;
    color: var(--text-secondary);
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-state h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
}

/* Responsive */
@media (max-width: 768px) {
    .header h1 {
        font-size: 1.8rem;
    }
    
    .stats-overview {
        gap: 10px;
    }
    
    .stat-card {
        padding: 15px 25px;
        min-width: 100px;
    }
    
    .habit-header {
        flex-direction: column;
        gap: 15px;
    }
    
    .form-row {
        flex-direction: column;
        gap: 0;
    }
    
    .habit-stats {
        justify-content: space-around;
    }
}

/* Today highlight */
.day-cell.today {
    outline: 2px solid var(--text-secondary);
    outline-offset: -1px;
}