:root {
            --primary: #0052B3;
            --primary-hover: #4338CA;
            --secondary: #9CA3AF;
            --secondary-hover: #6B7280;
            --card-bg: #f9f9f9;
            --text-main: #111827;
            --text-muted: #6B7280;
            --border: #E5E7EB;
            --success: #10B981;
            --danger: #DC2626;
        }

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


.calculator-wrapper {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: center;
            gap: 3.5rem;
            margin-bottom: 2rem;
            border: var(--form-border);
            border-radius: 8px;
            box-sizing: border-box;
            padding: 18px;
            background: #fff;
        }

        .fraction-block {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            background: #F3F4F6;
            padding: 1rem;
            border-radius: 12px;
        }

        .whole-number-input {
            width: 60px;
            height: 60px;
            text-align: center;
            font-size: 1.6rem;
            border: 1px solid var(--border);
            border-radius: 8px;
            font-weight: 600;
            outline: none;
            transition: border-color 0.2s;
        }

        .whole-number-input:focus, .fraction-input:focus {
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.2);
        }

        .fraction-col {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 0.5rem;
            width: 70px;
        }

        .fraction-input {
            width: 100%;
            text-align: center;
            padding: 0.5rem;
            border: 1px solid var(--border);
            border-radius: 6px;
            font-size: 1.6rem;
            outline: none;
            transition: border-color 0.2s;
        }

        .fraction-line-ui {
            width: 100%;
            height: 3px;
            background-color: var(--text-main);
            border-radius: 2px;
        }

        .operator-select {
            appearance: none;
            font-size: 1.8rem;
            padding: 0.75rem 3rem 0.75rem 1rem;
            border: 2px solid var(--border);
            border-radius: 50px;
            background-color: #fff;
            color: var(--primary);
            font-weight: 700;
            cursor: pointer;
            outline: none;
            text-align: center;
            background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%234F46E5'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
            background-repeat: no-repeat;
            background-position: right 0.75rem center;
            background-size: 1.25rem;
            box-shadow: 0 1px 2px rgba(0,0,0,0.05);
        }

        .button-group {
            display: flex;
            justify-content: center;
            gap: 1rem;
            margin-bottom: 1rem;
            border: var(--form-border);
            border-radius: 8px;
            box-sizing: border-box;
            padding: 18px;
            background: #fff;
        }

        .btn {
            padding: 1rem 2rem;
            border-radius: 50px;
            font-size: 1.8rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            border: none;
        }

        .btn-calculate {
            background-color: var(--primary);
            color: white;
            min-width: 200px;
        }

        .btn-calculate:hover {
            background-color: var(--primary-hover);
            box-shadow: 0 4px 6px rgba(79, 70, 229, 0.25);
        }

        .btn-reset {
            background-color: #F3F4F6;
            color: var(--text-main);
            border: 1px solid var(--border);
        }

        .btn-reset:hover {
            background-color: #E5E7EB;
        }

        .results-section {
            margin-top: 2.5rem;
            display: none;
            animation: fadeIn 0.4s ease-in-out;
        }

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

        .result-card {
            background-color: #EEF2FF;
            border: 1px solid #C7D2FE;
            padding: 1.5rem;
            border-radius: 12px;
            text-align: center;
            margin-bottom: 1.5rem;
        }

        .result-title {
            color: var(--primary);
            font-weight: 600;
            margin-bottom: 1rem;
            font-size: 1.9rem;
            text-transform: uppercase;
            letter-spacing: 0.05em;
        }

        .final-answer {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.75rem;
            font-size: 2.5rem;
            font-weight: 700;
            color: var(--text-main);
        }

        .decimal-result {
            margin-top: 0.75rem;
            font-size: 1.5rem;
            color: var(--text-muted);
            font-weight: 500;
        }

        .visual-container {
            margin-top: 2rem;
            padding-top: 2rem;
            border-top: 1px dashed #C7D2FE;
        }

        .visual-label-main {
            width: 100%;
            font-size: 1.9rem;
            color: var(--primary);
            font-weight: 700;
            margin-bottom: 1.25rem;
            text-transform: uppercase;
            text-align: center;
        }

        .visual-equation {
            display: flex;
            align-items: center;
            justify-content: center;
            flex-wrap: wrap;
            gap: 1.5rem;
        }

        .visual-term {
            display: flex;
            flex-direction: column;
            align-items: center;
            background: #fff;
            padding: 1.25rem;
            border-radius: 12px;
            border: 1px solid #C7D2FE;
            min-width: 140px;
            box-shadow: 0 2px 4px rgba(0,0,0,0.05);
        }
        
        .visual-term-label {
            font-size: 1.2rem;
            color: var(--text-muted);
            margin-bottom: 0.75rem;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 0.02em;
        }

        .visual-operator {
            font-size: 2rem;
            font-weight: bold;
            color: var(--text-main);
        }

        .pie-chart-svg {
            width: 75px;
            height: 75px;
            display: block;
            filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
            margin: 0.25rem;
        }
        
        .pie-chart-wrapper {
            display: flex; 
            flex-wrap: wrap; 
            gap: 8px; 
            justify-content: center; 
            max-width: 280px;
        }

        .inline-fraction {
            display: inline-flex;
            flex-direction: column;
            align-items: center;
            vertical-align: middle;
            margin: 0 0.2rem;
        }

        .inline-num {
            font-size: 1.4em;
            line-height: 1;
            padding-bottom: 2px;
        }

        .inline-den {
            font-size: 1.4em;
            line-height: 1;
            padding-top: 2px;
            border-top: 2px solid currentColor;
        }
        
        .formula-box {
            background-color: #F8FAFC;
            border: 1px solid #E2E8F0;
            border-radius: 6px;
            padding: 0.75rem;
            margin-top: 0.5rem;
            font-family: monospace;
            font-size: 1.4rem;
            color: #334155;
            display: inline-block;
            line-height: 1.5;
        }

        .steps-card {
            background-color: #fff;
            border: 1px solid var(--border);
            border-radius: 12px;
            padding: 1.5rem;
        }

        .steps-card h3 {
            font-size: 1.5rem;
            margin-bottom: 1rem;
            color: var(--text-main);
            border-bottom: 1px solid var(--border);
            padding-bottom: 0.5rem;
        }

        .step-item {
            margin-bottom: 1.25rem;
            line-height: 1.6;
            color: #374151;
            display: flex;
            align-items: baseline;
            gap: 0.75rem;
        }

        .step-num {
            background: var(--primary);
            color: white;
            border-radius: 50%;
            width: 24px;
            height: 24px;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            font-size: 1.8rem;
            font-weight: bold;
            flex-shrink: 0;
            margin-top: 0.25rem;
        }
        
        .step-content {
            flex: 1;
        }

        .error-msg {
            color: var(--danger);
            text-align: center;
            margin-top: 1rem;
            font-weight: 500;
            display: none;
            background: #FEE2E2;
            padding: 0.75rem;
            border-radius: 8px;
            border: 1px solid #FCA5A5;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .calculator-wrapper {
                flex-direction: column;
            }
            .operator-select {
                transform: rotate(90deg);
                margin: -0.5rem 0;
            }
            .visual-equation {
                flex-direction: column;
                gap: 1rem;
            }
            .button-group {
                flex-direction: column;
            }
            .btn {
                width: 100%;
            }
        }

        .conv-select {
    appearance: none;
    font-size: 1.1rem;
    padding: 0.75rem 2.5rem 0.75rem 1.5rem;
    border: 2px solid var(--border);
    border-radius: 50px;
    background-color: #fff;
    color: var(--primary);
    font-weight: 700;
    cursor: pointer;
    outline: none;
    text-align: center;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%234F46E5'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 1.25rem;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
    margin-bottom: 0.5rem;
    transition: all 0.2s;
}