:root {
    --primary: #3b82f6;
    --primary-hover: #2563eb;
    --secondary: #64748b;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --bg-color: #f1f5f9;
    --surface: #ffffff;
    --sidebar-bg: #1e293b;
    --sidebar-hover: #334155;
    --sidebar-text: #e2e8f0;
    --text-main: #334155;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --radius-md: 12px;
    --radius-lg: 16px;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-hover: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
}

/* App Layout */
.app-container {
    display: flex;
    height: 100vh;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background-color: var(--sidebar-bg);
    color: var(--sidebar-text);
    display: flex;
    flex-direction: column;
    transition: var(--transition);
}

.sidebar-header {
    padding: 24px;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 700;
    color: white;
}

.logo-icon {
    background: linear-gradient(135deg, var(--primary), #8b5cf6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 1.5rem;
}

.sidebar-nav {
    flex: 1;
    padding: 24px 16px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    background: transparent;
    border: none;
    color: var(--sidebar-text);
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    font-weight: 500;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    text-align: left;
}

.nav-item i {
    width: 20px;
    font-size: 1.1rem;
    opacity: 0.8;
}

.nav-item:hover, .nav-item.active {
    background-color: var(--sidebar-hover);
    color: white;
}

.nav-item.active i {
    color: var(--primary);
    opacity: 1;
}

.sidebar-footer {
    padding: 16px 24px;
    font-size: 0.8rem;
    color: rgba(255,255,255,0.5);
    border-top: 1px solid rgba(255,255,255,0.1);
}

/* Main Content */
.main-content {
    flex: 1;
    overflow-y: auto;
    padding: 32px 48px;
    position: relative;
}

.page-section {
    display: none;
    animation: fadeIn 0.4s ease forwards;
}

.page-section.active {
    display: block;
}

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

.page-header {
    margin-bottom: 32px;
}

.page-header h1 {
    font-size: 1.8rem;
    font-weight: 700;
    color: #1e293b;
    margin-bottom: 4px;
}

.page-header p {
    color: var(--text-muted);
}

/* Cards */
.card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border);
}

.card:hover {
    box-shadow: var(--shadow-md);
}

.card h2 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: #1e293b;
}

/* Forms */
.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 20px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 16px;
}

.form-group label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-main);
}

input[type="text"],
input[type="month"],
input[type="date"],
select,
textarea {
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-family: 'Inter', sans-serif;
    font-size: 1rem;
    transition: var(--transition);
    background-color: #f8fafc;
    color: var(--text-main);
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--primary);
    background-color: white;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-md);
    font-family: 'Inter', sans-serif;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn-secondary {
    background-color: #e2e8f0;
    color: #475569;
}

.btn-secondary:hover {
    background-color: #cbd5e1;
}

.w-100 { width: 100%; }
.mt-3 { margin-top: 16px; }
.mt-4 { margin-top: 24px; }
.mb-0 { margin-bottom: 0; }
.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.text-sm { font-size: 0.875rem; }
.hidden { display: none !important; }
.cursor-pointer { cursor: pointer; }
.d-flex { display: flex; }
.align-items-end { align-items: flex-end; }
.h-100 { height: 100%; }
.text-blue { color: var(--primary); }
.text-green { color: var(--success); }
.text-orange { color: var(--warning); }
.bg-blue { background-color: rgba(59, 130, 246, 0.1); color: var(--primary); }
.bg-green { background-color: rgba(16, 185, 129, 0.1); color: var(--success); }

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

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

.data-table th, .data-table td {
    padding: 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.data-table th {
    font-weight: 600;
    color: var(--text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    background-color: #f8fafc;
}

.data-table tbody tr {
    transition: var(--transition);
}

.data-table tbody tr:hover {
    background-color: #f8fafc;
}

/* Upload & Split Layout */
.split-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.card-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
}

.card-header h2 {
    margin-bottom: 0;
}

.icon-circle {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
}

.drop-zone {
    border: 2px dashed var(--border);
    border-radius: var(--radius-md);
    padding: 40px 20px;
    text-align: center;
    margin-top: 20px;
    cursor: pointer;
    transition: var(--transition);
    background-color: #f8fafc;
}

.drop-zone:hover, .drop-zone.dragover {
    border-color: var(--primary);
    background-color: rgba(59, 130, 246, 0.05);
}

.drop-icon {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: 16px;
    opacity: 0.8;
}

.result-box {
    background-color: #f8fafc;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 16px;
    margin-top: 16px;
    font-size: 0.9rem;
}

/* Filters */
.filters-row {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    align-items: flex-end;
}

.date-range-inputs {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* Summary Cards */
.summary-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.summary-card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    border-left: 4px solid var(--primary);
}

.summary-card:nth-child(2) { border-left-color: var(--success); }
.summary-card:nth-child(3) { border-left-color: var(--warning); }

.summary-card h3 {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
}

.summary-card .value {
    font-size: 1.75rem;
    font-weight: 700;
}