:root {
    --primary-color: #3498db;
    --background-color: #ffffff;
    --text-color: #333333;
    --border-color: #e1e1e1;
    --card-background: #f8f9fa;
    --success-color: #2ecc71;
    --warning-color: #f1c40f;
    --danger-color: #e74c3c;
}

body.dark-theme {
    --background-color: #1a1a1a;
    --text-color: #ffffff;
    --border-color: #333333;
    --card-background: #2d2d2d;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

h1 {
    font-size: 1.8rem;
    color: var(--primary-color);
}

.theme-toggle {
    cursor: pointer;
    font-size: 1.5rem;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 2rem;
}

.add-task-section, .tasks-section {
    background: var(--card-background);
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

h2 {
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
}

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

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

input, textarea, select {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background: var(--background-color);
    color: var(--text-color);
}

textarea {
    height: 100px;
    resize: vertical;
}

.add-task-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    width: 100%;
    margin-top: 1rem;
}

.add-task-btn:hover {
    opacity: 0.9;
}

.task-filters {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.filter-group {
    flex: 1;
}

.stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-top: 2rem;
}

.stat-card {
    background: var(--card-background);
    padding: 1.5rem;
    border-radius: 8px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: bold;
    color: var(--primary-color);
    display: block;
}

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

.task-item {
    background: var(--background-color);
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
    border-left: 4px solid var(--primary-color);
}

.task-item.bug-fix {
    border-left-color: var(--danger-color);
}

.task-item.documentation {
    border-left-color: var(--warning-color);
}

.task-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.5rem;
}

.task-title {
    font-weight: 600;
}

.task-category {
    font-size: 0.8rem;
    padding: 0.2rem 0.5rem;
    border-radius: 12px;
    background: var(--primary-color);
    color: white;
}

.task-category.bug-fix {
    background: var(--danger-color);
}

.task-category.documentation {
    background: var(--warning-color);
}

.task-description {
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.task-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    color: #666;
}

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

.task-actions button {
    background: none;
    border: none;
    cursor: pointer;
    opacity: 0.7;
}

.task-actions button:hover {
    opacity: 1;
}