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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
}

header {
    text-align: center;
    color: white;
    margin-bottom: 40px;
    padding: 20px;
}

header h1 {
    font-size: 3rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.tagline {
    font-size: 1.1rem;
    opacity: 0.95;
}

.create-section {
    background: white;
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    margin-bottom: 30px;
}

.create-section h2 {
    color: #333;
    margin-bottom: 20px;
    font-size: 1.5rem;
}

.input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}

.input-group input {
    flex: 1;
    padding: 12px 15px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.input-group input:focus {
    outline: none;
    border-color: #667eea;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary {
    background: #667eea;
    color: white;
}

.btn-primary:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #48bb78;
    color: white;
    font-size: 0.9rem;
    padding: 8px 16px;
}

.btn-secondary:hover {
    background: #38a169;
}

.btn-danger {
    background: #f56565;
    color: white;
    font-size: 0.9rem;
    padding: 8px 16px;
}

.btn-danger:hover {
    background: #e53e3e;
}

.checklist-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 20px;
}

.checklist-group {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s;
}

.checklist-group:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.25);
}

.group-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid #f0f0f0;
}

.group-header h3 {
    color: #333;
    font-size: 1.4rem;
}

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

.add-item-section {
    margin-bottom: 20px;
}

.add-item-section input {
    width: 100%;
    padding: 10px 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 0.95rem;
    margin-bottom: 10px;
    transition: border-color 0.3s;
}

.add-item-section input:focus {
    outline: none;
    border-color: #667eea;
}

.checklist-items {
    list-style: none;
}

.checklist-item {
    display: flex;
    align-items: center;
    padding: 12px;
    margin-bottom: 10px;
    background: #f8f9fa;
    border-radius: 8px;
    transition: all 0.3s;
}

.checklist-item:hover {
    background: #e9ecef;
}

.checklist-item.completed {
    opacity: 0.6;
}

.checklist-item input[type="checkbox"] {
    width: 20px;
    height: 20px;
    margin-right: 12px;
    cursor: pointer;
    accent-color: #667eea;
}

.checklist-item label {
    flex: 1;
    cursor: pointer;
    font-size: 1rem;
    color: #333;
}

.checklist-item.completed label {
    text-decoration: line-through;
    color: #999;
}

.delete-item {
    background: transparent;
    border: none;
    color: #f56565;
    cursor: pointer;
    font-size: 1.2rem;
    padding: 5px;
    opacity: 0;
    transition: opacity 0.3s;
}

.checklist-item:hover .delete-item {
    opacity: 1;
}

.delete-item:hover {
    color: #e53e3e;
}

.empty-state {
    text-align: center;
    color: white;
    padding: 60px 20px;
    font-size: 1.2rem;
    opacity: 0.9;
}

.empty-state p {
    margin-bottom: 10px;
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .checklist-container {
        grid-template-columns: 1fr;
    }

    .input-group {
        flex-direction: column;
    }

    .create-section {
        padding: 20px;
    }
}