/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f7fa;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

/* Header styles */
header {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 0;
    margin-bottom: 2rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 1.8rem;
    margin-bottom: 0.5rem;
}

nav ul {
    display: flex;
    list-style: none;
}

nav ul li {
    margin-right: 1rem;
}

nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

nav ul li a:hover {
    color: #3498db;
}

/* Main content styles */
main {
    min-height: calc(100vh - 180px);
    padding: 2rem 0;
}

h2 {
    color: #2c3e50;
    margin-bottom: 1.5rem;
    font-weight: 600;
}

/* Card styles */
.card {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

/* Form styles */
.form-group {
    margin-bottom: 1.5rem;
}

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

input[type="text"],
input[type="email"],
input[type="number"],
input[type="date"],
textarea,
select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="number"]:focus,
input[type="date"]:focus,
textarea:focus,
select:focus {
    border-color: #3498db;
    outline: none;
}

/* Button styles */
.btn {
    display: inline-block;
    background-color: #3498db;
    color: white;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    transition: background-color 0.3s;
}

.btn:hover {
    background-color: #2980b9;
}

.btn-secondary {
    background-color: #95a5a6;
}

.btn-secondary:hover {
    background-color: #7f8c8d;
}

.btn-danger {
    background-color: #e74c3c;
}

.btn-danger:hover {
    background-color: #c0392b;
}

/* Table styles */
table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1.5rem;
}

table th,
table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

table th {
    background-color: #f5f7fa;
    font-weight: 600;
}

/* Alert styles */
.alert {
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1.5rem;
}

.alert-success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

/* Footer styles */
footer {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 0;
    text-align: center;
}

/* Responsive styles */
@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
    }
    
    nav ul li {
        margin-right: 0;
        margin-bottom: 0.5rem;
    }
}

/* Invoice item styles */
.invoice-items {
    margin-bottom: 1.5rem;
}

.invoice-item {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    background-color: #f9f9f9;
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 0.5rem;
}

.invoice-item .form-group {
    flex: 1;
    min-width: 200px;
    margin-bottom: 0.5rem;
}

.add-item-btn {
    background-color: #2ecc71;
    margin-right: 1rem;
}

.add-item-btn:hover {
    background-color: #27ae60;
}

.remove-item-btn {
    background-color: #e74c3c;
}

.remove-item-btn:hover {
    background-color: #c0392b;
}

/* Search form */
.search-form {
    display: flex;
    margin-bottom: 1.5rem;
}

.search-form input {
    flex: 1;
    border-top-right-radius: 0;
    border-bottom-right-radius: 0;
}

.search-form .btn {
    border-top-left-radius: 0;
    border-bottom-left-radius: 0;
}

/* Invoice details */
.invoice-details {
    margin-bottom: 2rem;
}

.invoice-details dl {
    display: grid;
    grid-template-columns: 1fr 3fr;
    gap: 0.5rem;
}

.invoice-details dt {
    font-weight: 600;
    color: #7f8c8d;
}

.invoice-details dd {
    margin-left: 0;
}

.invoice-status {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-weight: 500;
    text-transform: uppercase;
    font-size: 0.875rem;
}

.status-pending {
    background-color: #ffeeba;
    color: #856404;
}

.status-paid {
    background-color: #c3e6cb;
    color: #155724;
}

.status-cancelled {
    background-color: #f5c6cb;
    color: #721c24;
}