/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

.d-flex {
    display: flex;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f4f6f9;
}

.container {
    max-width: 90%;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navbar */
.navbar {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand h1 {
    font-size: 1.5rem;
    margin: 0;
}

.nav-menu {
    list-style: none;
    display: flex;
    gap: 2rem;
}

.nav-menu a {
    color: white;
    text-decoration: none;
    transition: color 0.3s;
}

.nav-menu a:hover {
    color: #3498db;
}

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

/* Page Header */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.page-header h2 {
    color: #2c3e50;
    font-size: 2rem;
}

/* Cards */
.card {
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.card-body {
    padding: 2rem;
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #2c3e50;
}

.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-control:focus {
    outline: none;
    border-color: #3498db;
}

textarea.form-control {
    resize: vertical;
}

.required {
    color: #e74c3c;
}

.form-row {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
}

.col-md-1 { flex: 0 0 8.33%; }
.col-md-2 { flex: 0 0 16.66%; }
.col-md-3 { flex: 0 0 25%; }
.col-md-4 { flex: 0 0 33.33%; }
.col-md-6 { flex: 0 0 50%; }
.col-md-12 { flex: 0 0 100%; }

@media (max-width: 768px) {
    .form-row {
        flex-direction: column;
    }
    .col-md-1, .col-md-2, .col-md-3, .col-md-4, .col-md-6, .col-md-12 {
        flex: 0 0 100%;
    }
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    font-size: 1rem;
    transition: all 0.3s;
    text-align: center;
}

.btn-primary {
    background-color: #3498db;
    color: white;
}

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

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

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

.btn-success {
    background-color: #27ae60;
    color: white;
}

.btn-success:hover {
    background-color: #229954;
}

.btn-warning {
    background-color: #f39c12;
    color: white;
}

.btn-warning:hover {
    background-color: #e67e22;
}

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

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

.btn-info {
    background-color: #3498db;
    color: white;
}

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

.btn-sm {
    padding: 0.4rem 0.8rem;
    font-size: 0.875rem;
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

/* Tables */
.table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1rem;
}

.table thead {
    background-color: #34495e;
    color: white;
}

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

.table-bordered {
    border: 1px solid #ddd;
}

.table-bordered th,
.table-bordered td {
    border: 1px solid #ddd;
}

.table-borderless th,
.table-borderless td {
    border: none;
}

.table-sm th,
.table-sm td {
    padding: 0.5rem;
}

.table tbody tr:hover {
    background-color: #f8f9fa;
}

.table-header {
    background-color: #3498db !important;
    color: white !important;
}

/* Alerts */
.alert {
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
    position: relative;
}

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

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

.alert-warning {
    background-color: #fff3cd;
    color: #856404;
    border: 1px solid #ffeaa7;
}

.alert-info {
    background-color: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.alert-close {
    position: absolute;
    top: 0.5rem;
    right: 1rem;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: inherit;
}

/* Invoice Items */
.invoice-item {
    background-color: #f8f9fa;
    padding: 1.5rem;
    margin-bottom: 1rem;
    border-radius: 4px;
    border: 1px solid #dee2e6;
}

.item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.item-header h5 {
    margin: 0;
    color: #2c3e50;
}

.remove-item {
    padding: 0.25rem 0.75rem;
}

/* Invoice Totals */
.invoice-totals {
    background-color: #f8f9fa;
    padding: 1.5rem;
    border-radius: 4px;
    margin-top: 1rem;
}

.total-row {
    border-top: 2px solid #2c3e50;
    font-size: 1.125rem;
}

.justify-content-end {
    display: flex;
    justify-content: flex-end;
}

/* Custom Checkbox */
.custom-control {
    position: relative;
    display: block;
    min-height: 1.5rem;
    padding-left: 2rem;
}

.custom-control-input {
    position: absolute;
    left: 0;
    z-index: -1;
    width: 1.5rem;
    height: 1.5rem;
    opacity: 0;
}

.custom-control-label {
    position: relative;
    margin-bottom: 0;
    vertical-align: top;
    cursor: pointer;
}

.custom-control-label::before {
    position: absolute;
    top: 0.25rem;
    left: -2rem;
    display: block;
    width: 1.5rem;
    height: 1.5rem;
    pointer-events: none;
    content: "";
    background-color: #fff;
    border: 1px solid #adb5bd;
    border-radius: 0.25rem;
}

.custom-control-input:checked ~ .custom-control-label::before {
    background-color: #3498db;
    border-color: #3498db;
}

.custom-control-input:checked ~ .custom-control-label::after {
    position: absolute;
    top: 0.5rem;
    left: -1.75rem;
    display: block;
    width: 0.5rem;
    height: 0.875rem;
    content: "";
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.custom-checkbox .custom-control-label::before {
    border-radius: 0.25rem;
}

/* Form Actions */
.form-actions {
    margin-top: 2rem;
    display: flex;
    gap: 1rem;
}

/* Text Utilities */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-left { text-align: left; }
.text-muted {
    color: #6c757d;
}

/* Spacing Utilities */
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mb-5 { margin-bottom: 3rem; }
.mt-4 { margin-top: 1.5rem; }
.mt-5 { margin-top: 3rem; }

/* Invoice View */
.invoice-view {
    max-width: 900px;
    margin: 0 auto;
}

.company-logo {
    max-width: 250px;
    max-height: 120px;
}

.invoice-header {
    margin-bottom: 2rem;
}

/* Footer */
.footer {
    background-color: #2c3e50;
    color: white;
    text-align: center;
    padding: 1.5rem 0;
    margin-top: 3rem;
}

/* Responsive */
@media (max-width: 768px) {
    .navbar .container {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-menu {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }

    .page-header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    .table {
        font-size: 0.875rem;
    }

    .card-body {
        padding: 1rem;
    }
}