:root {
            --primary-color: #2563eb;
            --primary-hover: #1d4ed8;
            --bg-color: #f8fafc;
            --surface-color: #ffffff;
            --text-main: #1e293b;
            --text-muted: #64748b;
            --border-color: #e2e8f0;
            --border-radius: 8px;
            --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
        }

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

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
            background-color: var(--bg-color);
            color: var(--text-main);
            line-height: 1.6;
            padding: 20px;
        }

        header, main, footer {
            max-width: 1000px;
            margin: 0 auto;
        }

        header {
            text-align: center;
            margin-bottom: 40px;
            padding: 40px 20px;
            background-color: var(--surface-color);
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
        }

        h1 {
            color: var(--primary-color);
            margin-bottom: 15px;
            font-size: 2.5rem;
        }

        .hero-desc {
            color: var(--text-muted);
            font-size: 1.1rem;
            max-width: 800px;
            margin: 0 auto;
        }

        .calculator-container {
            background-color: var(--surface-color);
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
            overflow: hidden;
            margin-bottom: 40px;
        }

        .tabs {
            display: flex;
            border-bottom: 1px solid var(--border-color);
            background-color: #f1f5f9;
        }

        .tab-btn {
            flex: 1;
            padding: 15px 20px;
            border: none;
            background: none;
            font-size: 1rem;
            font-weight: 600;
            color: var(--text-muted);
            cursor: pointer;
            transition: all 0.3s ease;
            border-bottom: 3px solid transparent;
        }

        .tab-btn:hover {
            color: var(--primary-color);
            background-color: #e2e8f0;
        }

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

        .tab-content {
            display: none;
            padding: 30px;
        }

        .tab-content.active {
            display: block;
        }

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

        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: var(--text-main);
        }

        .input-wrapper {
            position: relative;
            display: flex;
            align-items: center;
        }

        .prefix, .suffix {
            position: absolute;
            color: var(--text-muted);
            padding: 0 12px;
            pointer-events: none;
        }

        .suffix { right: 0; }
        .prefix { left: 0; }

        input[type="number"] {
            width: 100%;
            padding: 12px 15px;
            border: 1px solid var(--border-color);
            border-radius: var(--border-radius);
            font-size: 1rem;
            transition: border-color 0.3s;
        }

        input[type="number"]:focus {
            outline: none;
            border-color: var(--primary-color);
            box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
        }

        .has-prefix input { padding-left: 30px; }
        .has-suffix input { padding-right: 35px; }

        button.calculate-btn {
            width: 100%;
            padding: 14px;
            background-color: var(--primary-color);
            color: white;
            border: none;
            border-radius: var(--border-radius);
            font-size: 1.1rem;
            font-weight: 600;
            cursor: pointer;
            transition: background-color 0.3s;
            margin-top: 10px;
        }

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

        .result-box {
            margin-top: 30px;
            padding: 20px;
            background-color: #eff6ff;
            border: 1px solid #bfdbfe;
            border-radius: var(--border-radius);
            display: none;
        }

        .result-box h3 {
            color: #1e3a8a;
            margin-bottom: 10px;
            font-size: 1.2rem;
        }

        .result-value {
            font-size: 2rem;
            font-weight: 700;
            color: var(--primary-color);
        }

        .result-breakdown {
            margin-top: 15px;
            padding-top: 15px;
            border-top: 1px dashed #93c5fd;
            font-size: 0.95rem;
            color: #1e40af;
        }

        /* Tier Specific Styles */
        .tier-row {
            display: flex;
            gap: 15px;
            margin-bottom: 15px;
            align-items: flex-end;
        }
        
        .tier-row .form-group {
            margin-bottom: 0;
            flex: 1;
        }

        .remove-tier {
            background-color: #ef4444;
            color: white;
            border: none;
            padding: 12px 15px;
            border-radius: var(--border-radius);
            cursor: pointer;
            height: 44px;
            font-weight: bold;
        }

        .add-tier-btn {
            background-color: #f1f5f9;
            color: var(--text-main);
            border: 1px dashed var(--border-color);
            padding: 10px 15px;
            border-radius: var(--border-radius);
            cursor: pointer;
            width: 100%;
            margin-bottom: 20px;
            font-weight: 600;
        }
        .add-tier-btn:hover {
            background-color: #e2e8f0;
        }

        article {
            background-color: var(--surface-color);
            padding: 40px;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
            margin-bottom: 40px;
        }

        article h2 {
            color: var(--text-main);
            margin-bottom: 20px;
            border-bottom: 2px solid var(--border-color);
            padding-bottom: 10px;
        }

        article h3 {
            color: var(--text-main);
            margin: 25px 0 10px 0;
        }

        article p, article ul {
            margin-bottom: 15px;
            color: var(--text-muted);
        }

        article ul {
            padding-left: 20px;
        }

        article li {
            margin-bottom: 5px;
        }

        /* AdSense Placeholder Styles */
        .ad-placeholder {
            background-color: #f8fafc;
            border: 2px dashed #cbd5e1;
            text-align: center;
            margin: 30px auto;
            border-radius: var(--border-radius);
            color: #94a3b8;
            font-size: 0.9rem;
            max-width: 728px; /* Standard leaderboard width */
            min-height: 90px; /* Standard leaderboard height */
            display: flex;
            align-items: center;
            justify-content: center;
            flex-direction: column;
            width: 100%;
        }

        .ad-placeholder span {
            display: block;
            margin-bottom: 5px;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 1px;
            font-size: 0.75rem;
        }

        footer {
            text-align: center;
            padding: 20px;
            color: var(--text-muted);
            font-size: 0.9rem;
        }

        @media (max-width: 600px) {
            .tabs { flex-direction: column; }
            .tab-btn { border-bottom: none; border-left: 3px solid transparent; text-align: left; }
            .tab-btn.active { border-bottom-color: transparent; border-left-color: var(--primary-color); }
            .tier-row { flex-direction: column; align-items: stretch; gap: 10px; background: #f8fafc; padding: 15px; border-radius: 8px;}
            .remove-tier { margin-top: 10px; }
        }