* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        :root {
            --primary: #1e40af;
            --primary-dark: #1e3a8a;
            --secondary: #3b82f6;
            --success: #10b981;
            --danger: #ef4444;
            --bg-light: #ffffff;
            --bg-secondary-light: #f8fafc;
            --text-light: #1e293b;
            --border-light: #e2e8f0;
            --card-light: #ffffff;
            --bg-dark: #0f172a;
            --bg-secondary-dark: #1e293b;
            --text-dark: #f1f5f9;
            --border-dark: #334155;
            --card-dark: #1e293b;
        }
        
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            line-height: 1.6;
            transition: background-color 0.3s ease;
        }
        
        body.light-mode {
            background: var(--bg-secondary-light);
            color: var(--text-light);
        }
        
        body.dark-mode {
            background: var(--bg-dark);
            color: var(--text-dark);
        }
        
        header {
            position: fixed;
            top: 0;
            width: 100%;
            z-index: 1000;
            backdrop-filter: blur(10px);
        }
        
        .light-mode header {
            background: rgba(255, 255, 255, 0.95);
            border-bottom: 1px solid var(--border-light);
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }
        
        .dark-mode header {
            background: rgba(15, 23, 42, 0.95);
            border-bottom: 1px solid var(--border-dark);
        }
        
        nav {
            max-width: 1200px;
            margin: 0 auto;
            padding: 1rem 2rem;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .nav-menu {
            display: flex;
            list-style: none;
            gap: 2rem;
            align-items: center;
        }
        
        .nav-item {
            position: relative;
        }
        
        .nav-link {
            text-decoration: none;
            font-weight: 500;
            transition: color 0.3s ease;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            cursor: pointer;
        }
        
        .light-mode .nav-link {
            color: var(--text-light);
        }
        
        .dark-mode .nav-link {
            color: var(--text-dark);
        }
        
        .nav-link:hover {
            color: var(--primary);
        }
        
        /* Dropdown Menu */
        .dropdown {
            position: relative;
        }
        
        .dropdown-menu {
            position: absolute;
            top: 100%;
            left: 0;
            margin-top: 0.5rem;
            min-width: 250px;
            border-radius: 12px;
            padding: 0.5rem;
            opacity: 0;
            visibility: hidden;
            transform: translateY(-10px);
            transition: all 0.3s ease;
            box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
        }
        
        .light-mode .dropdown-menu {
            background: var(--card-light);
            border: 1px solid var(--border-light);
        }
        
        .dark-mode .dropdown-menu {
            background: var(--card-dark);
            border: 1px solid var(--border-dark);
        }
        
        .dropdown:hover .dropdown-menu {
            opacity: 1;
            visibility: visible;
            transform: translateY(0);
        }
        
        .dropdown-item {
            padding: 0.45rem 1rem;
            transition: all 0.2s ease;
            cursor: pointer;
            list-style: none;
            border-bottom: 1px solid #eee;
        }
        
        .dropdown-item a {
            color: #1e293b;
            font-size:15px;
            text-decoration:none;
        }
        
        .dropdown-columns {
            display: grid;
            grid-template-columns: 1fr 1fr; /* 2 sütun */
            column-gap: 20px;
            padding: 10px;
            list-style: none;
        }
        
        .dropdown-columns .dropdown-item {
            white-space: nowrap;
        }
        
                
                .nav-item.dropdown .dropdown-menu {
            left: 50%;
            transform: translateX(-50%);
            max-width: 90vw;
        }

        
        .light-mode .dropdown-item:hover {
            background: var(--bg-secondary-light);
        }
        
        .dark-mode .dropdown-item:hover {
            background: var(--bg-secondary-dark);
        }
        
        .dropdown-item h4 {
            font-size: 0.9rem;
            margin-bottom: 0.25rem;
        }
        
        .dropdown-item p {
            font-size: 0.75rem;
            opacity: 0.7;
        }
        
        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            text-decoration: none;
        }
        
        .theme-toggle {
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            padding: 0.5rem;
            border-radius: 50%;
            transition: all 0.3s ease;
        }
        
        .theme-toggle:hover {
            transform: rotate(180deg);
        }
        
        .container {
            max-width: 1200px;
            margin: 100px auto 2rem;
            padding: 0 2rem;
        }
        
        .page-header {
            text-align: center;
            margin-bottom: 3rem;
        }
        
        .page-header h1 {
            font-size: 2.5rem;
            font-weight: 800;
            margin-bottom: 1rem;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }
        
        .calculator-layout {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 2rem;
            margin-bottom: 3rem;
        }
        
        .card {
            padding: 2rem;
            border-radius: 16px;
            transition: all 0.3s ease;
        }
        
        .light-mode .card {
            background: var(--card-light);
            border: 1px solid var(--border-light);
            box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        }
        
        .dark-mode .card {
            background: var(--card-dark);
            border: 1px solid var(--border-dark);
        }
        
        .card h2 {
            font-size: 1.5rem;
            margin-bottom: 1.5rem;
        }
        
        .form-group {
            margin-bottom: 1.5rem;
        }
        
        .form-group label {
            display: block;
            margin-bottom: 0.5rem;
            font-weight: 600;
            font-size: 0.9rem;
        }
        
        .input-wrapper {
            position: relative;
        }
        
        .input-wrapper input, .input-wrapper select {
            width: 100%;
            padding: 0.875rem 1rem;
            border-radius: 8px;
            border: 2px solid;
            font-size: 1rem;
            transition: all 0.3s ease;
        }
        
        .light-mode .input-wrapper input, .light-mode .input-wrapper select {
            background: var(--bg-light);
            border-color: var(--border-light);
            color: var(--text-light);
        }
        
        .dark-mode .input-wrapper input, .dark-mode .input-wrapper select {
            background: var(--bg-secondary-dark);
            border-color: var(--border-dark);
            color: var(--text-dark);
        }
        
        .input-wrapper input:focus, .input-wrapper select:focus {
            outline: none;
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(30, 64, 175, 0.1);
        }
        
        .input-suffix {
            position: absolute;
            right: 1rem;
            top: 50%;
            transform: translateY(-50%);
            opacity: 0.6;
            font-weight: 600;
        }
        
        .help-text {
            font-size: 0.8rem;
            opacity: 0.7;
            margin-top: 0.25rem;
        }
        
        .btn {
            padding: 1rem 2rem;
            border-radius: 8px;
            font-weight: 600;
            border: none;
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 1rem;
            width: 100%;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            box-shadow: 0 4px 15px rgba(30, 64, 175, 0.4);
        }
        
        .btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(30, 64, 175, 0.5);
        }
        
        .result-card {
            padding: 1.5rem;
            border-radius: 12px;
            margin-bottom: 1rem;
        }
        
        .result-card.highlight {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
        }
        
        .light-mode .result-card:not(.highlight) {
            background: var(--bg-secondary-light);
        }
        
        .dark-mode .result-card:not(.highlight) {
            background: var(--bg-secondary-dark);
        }
        
        .result-row {
            display: flex;
            justify-content: space-between;
            padding: 0.75rem 0;
            border-bottom: 1px solid rgba(255,255,255,0.1);
        }
        
        .result-row:last-child {
            border-bottom: none;
        }
        
        .result-value {
            font-weight: 700;
            font-size: 1.1rem;
        }
        
        .result-card.highlight .result-value {
            font-size: 2rem;
        }
        
        .payment-table {
            width: 100%;
            border-collapse: collapse;
            margin-top: 1rem;
        }
        
        .payment-table th, .payment-table td {
            padding: 0.875rem;
            text-align: left;
            border-bottom: 1px solid;
        }
        
        .light-mode .payment-table th, .light-mode .payment-table td {
            border-color: var(--border-light);
        }
        
        .dark-mode .payment-table th, .dark-mode .payment-table td {
            border-color: var(--border-dark);
        }
        
        .payment-table th {
            font-weight: 600;
            font-size: 0.9rem;
        }
        
        .payment-table .amount {
            text-align: right;
            font-weight: 600;
        }
        
        @media (max-width: 968px) {
            .calculator-layout {
                grid-template-columns: 1fr;
            }
            
            .page-header h1 {
                font-size: 2rem;
            }
        }
        
        .info-card { margin-bottom:30px; }
        
        
        /* ACCORDION */
.accordion {
    margin-top: 1rem;
}

.accordion-item {
    border: 1px solid var(--border);
    border-radius: 12px;
    margin-bottom: 12px;
    overflow: hidden;
    background: var(--card-bg);
}

.accordion-header {
    width: 100%;
    background: transparent;
    border: none;
    padding: 1rem 1.2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text);
    transition: background 0.3s ease;
}

.accordion-header:hover {
    background: rgba(0, 0, 0, 0.04);
}

.dark-mode .accordion-header:hover {
    background: rgba(255, 255, 255, 0.05);
}

.accordion-icon {
    font-size: 1.4rem;
    transition: transform 0.3s ease;
}

.accordion-item.active .accordion-icon {
    transform: rotate(45deg);
}

.accordion-body {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
    padding: 0 1.2rem;
}

.accordion-body p {
    padding: 1rem 0;
    line-height: 1.7;
    color: var(--text-muted);
}