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

:root {
    --primary: #2563eb;
    --primary-light: #60a5fa;
    --primary-dark: #1d4ed8;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --dark: #0f172a;
    --gray-900: #1e293b;
    --gray-800: #334155;
    --gray-700: #475569;
    --gray-600: #64748b;
    --gray-500: #71839b;
    --gray-400: #94a3b8;
    --gray-300: #cbd5e1;
    --gray-200: #e2e8f0;
    --gray-100: #f1f5f9;
    --white: #ffffff;
}

html, body {
    height: 100%;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
    background: linear-gradient(135deg, #f0f4f8 0%, #d9e2ec 100%);
    color: var(--gray-900);
}

/* Layout */
.container {
    display: grid;
    grid-template-columns: 280px 1fr;
    min-height: 100vh;
}

/* Sidebar */
.navbar {
    background: linear-gradient(180deg, var(--dark) 0%, #1a2d4d 100%);
    padding: 30px 20px;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    box-shadow: 10px 0 40px rgba(0, 0, 0, 0.2);
}

.nav-brand {
    font-size: 22px;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-light) 0%, #93c5fd 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 2px solid rgba(96, 165, 250, 0.2);
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.nav-links a {
    padding: 14px 16px;
    border-radius: 10px;
    text-decoration: none;
    color: var(--gray-400);
    display: block;
    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    font-weight: 500;
    font-size: 14px;
    position: relative;
    overflow: hidden;
}

.nav-links a::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--primary-light), var(--primary));
    transform: scaleY(0);
    transform-origin: top;
    transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

.nav-links a:hover {
    background: rgba(96, 165, 250, 0.15);
    color: var(--primary-light);
}

.nav-links a:hover::before {
    transform: scaleY(1);
}

.nav-links a.active {
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.2), rgba(96, 165, 250, 0.1));
    color: var(--primary-light);
}

.nav-links a.active::before {
    transform: scaleY(1);
}

.logout {
    color: var(--danger) !important;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid rgba(239, 68, 68, 0.2);
}

.user-info {
    color: var(--gray-400);
    font-size: 12px;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--gray-800);
    font-weight: 500;
}

/* Main */
.main {
    padding: 50px;
    overflow-y: auto;
    background: linear-gradient(135deg, #f0f4f8 0%, #d9e2ec 100%);
}

.main h2 {
    font-size: 36px;
    font-weight: 800;
    margin-bottom: 15px;
    background: linear-gradient(135deg, var(--dark) 0%, var(--gray-900) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -1px;
}

.main > p {
    color: var(--gray-600);
    margin-bottom: 40px;
    font-size: 16px;
}

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 28px;
    margin-bottom: 50px;
}

.stat-card {
    background: var(--white);
    padding: 28px;
    border-radius: 16px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.5);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--primary-light));
}

.stat-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(37, 99, 235, 0.15);
}

.stat-num {
    font-size: 48px;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 12px;
    line-height: 1;
}

.stat-label {
    font-size: 13px;
    color: var(--gray-600);
    text-transform: uppercase;
    font-weight: 700;
    letter-spacing: 1px;
}

/* Cards/Sections */
.section {
    background: var(--white);
    padding: 32px;
    border-radius: 16px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    margin-bottom: 32px;
    border: 1px solid rgba(255, 255, 255, 0.5);
    transition: all 0.3s ease;
}

.section h3 {
    font-size: 20px;
    margin-bottom: 28px;
    color: var(--gray-900);
    font-weight: 700;
}

/* Forms */
.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin: 28px 0;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    margin-bottom: 10px;
    font-weight: 600;
    color: var(--gray-900);
    font-size: 14px;
}

.form-group input,
.form-group select {
    padding: 12px 16px;
    border: 2px solid var(--gray-200);
    border-radius: 10px;
    font-size: 14px;
    font-family: inherit;
    transition: all 0.3s ease;
    background: var(--white);
}

.form-group input::placeholder {
    color: var(--gray-400);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
    background: var(--white);
}

/* Tables */
.table {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
}

.table thead {
    background: linear-gradient(135deg, #f8fafc 0%, #f0f4f8 100%);
    border-bottom: 2px solid var(--gray-200);
}

.table th {
    padding: 16px;
    text-align: left;
    font-weight: 700;
    color: var(--gray-900);
    text-transform: uppercase;
    font-size: 12px;
    letter-spacing: 0.5px;
}

.table td {
    padding: 16px;
    border-bottom: 1px solid var(--gray-200);
    color: var(--gray-700);
}

.table tbody tr {
    transition: all 0.2s ease;
}

.table tbody tr:hover {
    background: #f9fafb;
}

.urgent-row {
    background: rgba(239, 68, 68, 0.05);
    border-left: 4px solid var(--danger);
}

.warning-row {
    background: rgba(245, 158, 11, 0.05);
    border-left: 4px solid var(--warning);
}

/* Status */
.status {
    display: inline-block;
    padding: 8px 14px;
    border-radius: 8px;
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.status.paid {
    background: rgba(16, 185, 129, 0.15);
    color: var(--success);
}

.status.unpaid {
    background: rgba(239, 68, 68, 0.15);
    color: var(--danger);
}

/* Buttons */
.btn {
    padding: 12px 28px;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: var(--white);
    border: none;
    border-radius: 10px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    font-size: 14px;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 24px rgba(37, 99, 235, 0.4);
}

.btn:active {
    transform: translateY(-1px);
}

.btn-small {
    padding: 10px 16px;
    background: var(--gray-200);
    color: var(--gray-900);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 12px;
    transition: all 0.3s ease;
    font-weight: 600;
}

.btn-small:hover {
    background: var(--gray-300);
}

.btn-small.delete {
    background: rgba(239, 68, 68, 0.15);
    color: var(--danger);
}

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

/* Messages */
.error {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger);
    padding: 16px;
    border-radius: 10px;
    margin-bottom: 24px;
    border-left: 4px solid var(--danger);
    font-weight: 600;
}

.success-box {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success);
    padding: 16px;
    border-radius: 10px;
    margin-bottom: 24px;
    border-left: 4px solid var(--success);
    font-weight: 600;
}

.info {
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary);
    padding: 16px;
    border-radius: 10px;
    margin-bottom: 24px;
    border-left: 4px solid var(--primary);
    font-size: 14px;
    line-height: 1.6;
    font-weight: 600;
}

.no-data {
    text-align: center;
    color: var(--gray-600);
    padding: 80px 20px;
    font-size: 16px;
}

/* Quick Links */
.quick {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
    margin-top: 50px;
}

.link-card {
    background: var(--white);
    padding: 0;
    border-radius: 16px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
    text-decoration: none;
    color: inherit;
    border: 1px solid rgba(255, 255, 255, 0.5);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.link-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--primary-light));
    width: 0;
    transition: width 0.4s ease;
}

.link-card:hover {
    border-color: var(--primary);
    box-shadow: 0 16px 32px rgba(37, 99, 235, 0.2);
    transform: translateY(-6px);
}

.link-card:hover::before {
    width: 100%;
}

.link-card h4 {
    color: var(--primary);
    margin-bottom: 8px;
    font-size: 18px;
    font-weight: 700;
}

.link-card p {
    color: var(--gray-600);
    font-size: 13px;
    margin: 0;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        grid-template-columns: 1fr;
    }

    .navbar {
        height: auto;
        position: relative;
        border-bottom: 1px solid var(--gray-800);
        padding: 20px;
    }

    .nav-links {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
        gap: 10px;
    }

    .main {
        padding: 20px;
    }

    .main h2 {
        font-size: 24px;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .form-grid {
        grid-template-columns: 1fr;
    }

    .table {
        font-size: 12px;
    }

    .table th,
    .table td {
        padding: 10px;
    }

    .quick {
        grid-template-columns: 1fr;
    }
}

.loading {
    text-align: center;
    padding: 40px;
    color: var(--gray-600);
}

.selector {
    margin-bottom: 24px;
}

.selector label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--gray-900);
}

.selector select {
    padding: 12px 16px;
    border: 2px solid var(--gray-200);
    border-radius: 10px;
    font-size: 14px;
    width: 100%;
    max-width: 300px;
}