:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --background-color: #ecf0f1;
    --text-color: #34495e;
    --accent-color: #e74c3c;
    --positive-color: #28a745;
    --negative-color: #dc3545;
}

body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: var(--background-color);
    color: var(--text-color);
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: auto;
    overflow: hidden;
    padding: 20px;
}

nav {
    background-color: var(--primary-color);
    padding: 1rem 0;
}

nav ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
}

nav ul li {
    margin: 0 10px;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: bold;
    transition: color 0.3s ease;
}

nav ul li a:hover {
    color: var(--secondary-color);
}

h1, h2 {
    color: var(--primary-color);
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

.form-group input, .form-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 16px;
}

.btn {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s ease;
}

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

.btn-small {
    padding: 5px 10px;
    font-size: 14px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
    background-color: white;
    box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
}

th, td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

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

tr:nth-child(even) {
    background-color: #f2f2f2;
}

.error {
    color: var(--accent-color);
    margin-bottom: 10px;
}

.summary {
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
}

.summary-item {
    background-color: white;
    padding: 20px;
    border-radius: 4px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24);
    flex: 1;
    margin: 0 10px;
    text-align: center;
}

.summary-item h3 {
    margin-top: 0;
    color: var(--primary-color);
}

.summary-item p {
    font-size: 24px;
    font-weight: bold;
    margin: 10px 0 0;
}

.date-selector {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    background-color: #f8f9fa;
    padding: 15px;
    border-radius: 5px;
}

.date-selector .form-group {
    margin-bottom: 0;
    margin-right: 15px;
}

.date-selector select {
    padding: 5px 10px;
    border-radius: 4px;
    border: 1px solid #ced4da;
}

.date-selector .btn {
    margin-left: auto;
}

.positive {
    color: var(--positive-color);
}

.negative {
    color: var(--negative-color);
}

.summary-item.positive {
    background-color: #d4edda;
    border-color: #c3e6cb;
}

.summary-item.negative {
    background-color: #f8d7da;
    border-color: #f5c6cb;
}

table tr.positive {
    background-color: #d4edda;
}

table tr.negative {
    background-color: #f8d7da;
}

table tr.positive:nth-child(even) {
    background-color: #c3e6cb;
}

table tr.negative:nth-child(even) {
    background-color: #f5c6cb;
}

.message {
    padding: 10px;
    margin-bottom: 20px;
    border-radius: 4px;
    background-color: #d4edda;
    border-color: #c3e6cb;
    color: #155724;
}

@media(max-width: 768px) {
    .container {
        width: 95%;
    }
    
    nav ul {
        flex-direction: column;
    }
    
    nav ul li {
        margin: 5px 0;
    }
    
    .summary {
        flex-direction: column;
    }
    
    .summary-item {
        margin: 10px 0;
    }

    .date-selector {
        flex-direction: column;
    }

    .date-selector .form-group {
        margin-bottom: 10px;
        margin-right: 0;
    }

    .date-selector .btn {
        width: 100%;
        margin-top: 10px;
    }
}