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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --secondary-color: #64748b;
    --success-color: #22c55e;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --info-color: #3b82f6;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    font-size: 16px;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 15px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 15px;
}

.logo a {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.nav {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.nav-link {
    padding: 8px 16px;
    color: var(--text-color);
    text-decoration: none;
    border-radius: 6px;
    transition: all 0.2s;
}

.nav-link:hover {
    background-color: var(--bg-color);
    color: var(--primary-color);
}

.user-menu {
    display: flex;
    align-items: center;
    gap: 15px;
}

.username {
    color: var(--text-muted);
    font-weight: 500;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.2s;
    text-align: center;
}

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

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

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

.btn-secondary:hover {
    background-color: #475569;
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
}

.btn-danger:hover {
    background-color: #dc2626;
}

.btn-sm {
    padding: 6px 12px;
    font-size: 0.875rem;
}

.btn-block {
    display: block;
    width: 100%;
}

/* Forms */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-color);
}

.form-control,
input[type="text"],
input[type="email"],
input[type="password"],
input[type="number"],
input[type="date"],
select,
textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
    transition: all 0.2s;
    background-color: white;
}

.form-control:focus,
input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

/* Auth Pages */
.auth-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.auth-container {
    width: 100%;
    max-width: 400px;
    padding: 20px;
}

.auth-box {
    background: white;
    padding: 40px;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
}

.auth-box h1 {
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 10px;
    font-size: 1.8rem;
}

.auth-box h2 {
    text-align: center;
    color: var(--text-muted);
    margin-bottom: 30px;
    font-size: 1.2rem;
    font-weight: 400;
}

.auth-footer {
    text-align: center;
    margin-top: 20px;
    color: var(--text-muted);
}

.auth-footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.auth-footer a:hover {
    text-decoration: underline;
}

/* Alerts */
.alert {
    padding: 12px 16px;
    border-radius: 6px;
    margin-bottom: 20px;
}

.alert-error {
    background-color: #fee2e2;
    color: #991b1b;
    border: 1px solid #fecaca;
}

.alert-success {
    background-color: #d1fae5;
    color: #065f46;
    border: 1px solid #a7f3d0;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background: var(--card-bg);
    padding: 24px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.stat-card.positive {
    border-left: 4px solid var(--success-color);
}

.stat-card.negative {
    border-left: 4px solid var(--danger-color);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-color);
    margin-bottom: 8px;
}

.stat-card.positive .stat-value {
    color: var(--success-color);
}

.stat-card.negative .stat-value {
    color: var(--danger-color);
}

.stat-label {
    color: var(--text-muted);
    font-size: 0.875rem;
    font-weight: 500;
}

/* Section */
.section {
    background: var(--card-bg);
    padding: 24px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

.section h2 {
    margin-bottom: 20px;
    color: var(--text-color);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
    gap: 15px;
}

.section-header h1,
.section-header h2 {
    margin: 0;
}

/* Table */
.table-responsive {
    overflow-x: auto;
}

.table {
    width: 100%;
    border-collapse: collapse;
    background: white;
}

.table thead {
    background-color: var(--bg-color);
}

.table th {
    padding: 12px;
    text-align: left;
    font-weight: 600;
    color: var(--text-color);
    border-bottom: 2px solid var(--border-color);
}

.table td {
    padding: 12px;
    border-bottom: 1px solid var(--border-color);
}

.table tbody tr:hover {
    background-color: var(--bg-color);
}

.text-center {
    text-align: center;
}

.text-success {
    color: var(--success-color);
    font-weight: 600;
}

.text-danger {
    color: var(--danger-color);
    font-weight: 600;
}

/* Badges */
.badge {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.badge-success {
    background-color: #d1fae5;
    color: #065f46;
}

.badge-danger {
    background-color: #fee2e2;
    color: #991b1b;
}

.badge-warning {
    background-color: #fef3c7;
    color: #92400e;
}

.badge-info {
    background-color: #dbeafe;
    color: #1e40af;
}

.badge-secondary {
    background-color: #f1f5f9;
    color: #475569;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-muted);
}

.empty-state p {
    margin-bottom: 20px;
    font-size: 1.1rem;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.modal-content {
    background-color: white;
    border-radius: 12px;
    max-width: 600px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
}

.modal-header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h2 {
    margin: 0;
    font-size: 1.5rem;
}

.close {
    font-size: 2rem;
    color: var(--text-muted);
    cursor: pointer;
    line-height: 1;
}

.close:hover {
    color: var(--text-color);
}

.modal-content form {
    padding: 24px;
}

.modal-footer {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
    margin-top: 20px;
}

/* Filters */
.filters {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
    margin-bottom: 20px;
}

/* Calculator */
.calculator-header {
    text-align: center;
    margin-bottom: 30px;
}

.calculator-header h1 {
    margin-bottom: 10px;
}

.calculator-header .subtitle {
    color: var(--text-muted);
    font-size: 1.1rem;
}

.calculator-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 30px;
    border-bottom: 2px solid var(--border-color);
    flex-wrap: wrap;
}

.tab-btn {
    background: none;
    border: none;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-muted);
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: all 0.3s;
}

.tab-btn:hover {
    color: var(--primary-color);
}

.tab-btn.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.calculator-tab {
    display: none;
}

.calculator-tab.active {
    display: block;
    animation: fadeIn 0.3s;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.calculator-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.calculator-card {
    background: var(--card-bg);
    padding: 24px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.calculator-card h2 {
    margin-bottom: 20px;
    font-size: 1.3rem;
    color: var(--text-color);
}

.calculator-card-large {
    background: var(--card-bg);
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    max-width: 900px;
    margin: 0 auto;
}

.calculator-card-large h2 {
    margin-bottom: 10px;
    font-size: 1.8rem;
    color: var(--text-color);
}

.calculator-desc {
    color: var(--text-muted);
    margin-bottom: 30px;
    font-size: 1rem;
}

.btn-large {
    padding: 14px 32px;
    font-size: 1.1rem;
}

.result-box {
    margin-top: 20px;
    padding: 20px;
    background-color: var(--bg-color);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

.result-box h3 {
    margin-bottom: 12px;
    font-size: 1.1rem;
    color: var(--text-color);
}

.result-box p {
    margin: 8px 0;
    font-size: 1rem;
}

.result-box-large {
    margin-top: 30px;
    padding: 24px;
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    border-radius: 12px;
    border: 2px solid var(--border-color);
}

.result-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.result-item {
    background: white;
    padding: 20px;
    border-radius: 8px;
    text-align: center;
    box-shadow: var(--shadow);
}

.result-item.highlight {
    border: 2px solid var(--primary-color);
}

.result-label {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 8px;
    font-weight: 500;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
}

.result-item small {
    display: block;
    margin-top: 5px;
    color: var(--text-muted);
    font-size: 0.875rem;
}

.result-info {
    background: white;
    padding: 15px 20px;
    border-radius: 8px;
    margin-top: 15px;
}

.result-info p {
    margin: 5px 0;
}

.margin-alert {
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
    font-weight: 500;
    text-align: center;
}

.margin-alert.alert-success {
    background-color: #d1fae5;
    color: #065f46;
    border: 1px solid #a7f3d0;
}

.margin-alert.alert-warning {
    background-color: #fef3c7;
    color: #92400e;
    border: 1px solid #fde68a;
}

.margin-alert.alert-danger {
    background-color: #fee2e2;
    color: #991b1b;
    border: 1px solid #fecaca;
}

.large-result {
    font-size: 2rem;
    font-weight: 700;
    margin: 15px 0;
}

.text-warning {
    color: var(--warning-color);
    font-weight: 600;
}

/* Responsive */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .nav {
        width: 100%;
    }
    
    .user-menu {
        width: 100%;
        justify-content: space-between;
    }
    
    .stats-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    }
    
    .calculator-grid {
        grid-template-columns: 1fr;
    }
    
    .calculator-card-large {
        padding: 20px;
    }
    
    .calculator-tabs {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    .tab-btn {
        padding: 10px 16px;
        font-size: 0.9rem;
        white-space: nowrap;
    }
    
    .result-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    }
    
    .result-value {
        font-size: 1.2rem;
    }
    
    .auth-box {
        padding: 30px 20px;
    }
    
    .table {
        font-size: 0.875rem;
    }
    
    .table th,
    .table td {
        padding: 8px;
    }
}

@media (max-width: 480px) {
    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .filters {
        grid-template-columns: 1fr;
    }
}

/* Utilities */
h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-color);
    margin-bottom: 20px;
}

h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-color);
}

a {
    color: var(--primary-color);
}

a:hover {
    color: var(--primary-dark);
}