@counter-style parenthesisalplist { system: extends lower-alpha; suffix: ') '; prefix: '('; }
        * { box-sizing: border-box; }

        :root {
            --main-color: #1A48EE;
            --secondary-color: #008AFF;
            --tertiary-color: #2c20E6;
            --secondary-background: #f9f9f9;
            --main-background: #e5f3ff;
            --tertiary-background: #e6e5ea;
            --color-white: #ffffff;
            --color-error-dark: #c53030;
            --color-green: #16a34a;
            --color-green-dark: #047857;
            --color-light-green: #D1FAE5;
            --color-contrast-green: #065F46;
            --border-color: #cbd5e1;
            --color-gray: #334155;
            --color-dark: #1a202c;
        }

        body { 
            margin: 0;
            font-family: Arial, Helvetica, sans-serif;
            background-color: var(--main-background);
            display: flex;
            flex-direction: column;
            min-height: 100vh;
            overflow-x: hidden;
        }

        .skip-link {
            position: absolute;
            top: -40px;
            left: 0;
            background: var(--main-color);
            color: white;
            padding: 8px;
            z-index: 100;
            transition: top 0.2s;
            text-decoration: none;
        }
        .skip-link:focus { top: 0; }

        h1 { 
            width: 100%; 
            display: inline-block; 
            text-align: center; 
            margin-top: 0px; 
            color: #1a202c;
            margin-bottom: 20px;
            font-weight: inherit;
        }

        h2 { 
            color: var(--main-color); 
            border-bottom: 2px solid var(--secondary-color); 
            padding-bottom: 0.5rem; 
            margin-bottom: 1rem;
            font-size: 1.5rem;
            font-weight: inherit;
        }

        .articlecontainer {
            margin: auto;
            max-width: 1280px;
            padding: 0 16px;
            width: 100%;
        }

        .card { 
            background: var(--color-white); 
            padding: 40px; 
            margin-bottom: 30px; 
            border: 1px solid var(--border-color);
            border-radius: 4px;
        }

        .info-section { border-left: 5px solid var(--tertiary-color); padding-left: 20px; }
        
        .ad-container {
            width: 100%;
            margin: 2rem auto;
            text-align: center;
            min-height: 90px;
        }

        /* --- Input Section --- */
        .input-group { display: flex; gap: 15px; margin-top: 10px; flex-wrap: wrap; }
        label { display: block; font-weight: bold; margin-bottom: 8px; color: var(--color-dark); }

        input[type="text"] {
            flex: 1; min-width: 250px; padding: 16px 20px; border: 2px solid var(--border-color);
            border-radius: 4px; font-size: 1.2rem; outline: none; font-family: 'Courier New', monospace;
            background-color: #fff;
        }

        input[type="text"]:focus-visible { border-color: var(--main-color); outline: 3px solid var(--main-color); outline-offset: 1px; }

        .btn-primary {
            background-color: var(--main-color); color: white; border: none;
            padding: 16px 36px; border-radius: 4px; font-weight: bold; font-size: 1.1rem;
            cursor: pointer; display: flex; align-items: center; justify-content: center;
        }
        .btn-primary:hover, .btn-primary:focus { background-color: var(--tertiary-color); outline: 2px solid var(--color-dark); outline-offset: 2px; }

        .example-area { margin-top: 25px; display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
        .example-chip {
            background-color: var(--tertiary-background); color: var(--color-dark); padding: 8px 16px;
            border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; border: 1px solid var(--border-color);
            display: flex; align-items: center; justify-content: center;
            font-family: 'Courier New', monospace;
        }
        .example-chip:hover, .example-chip:focus { background-color: var(--secondary-color); color: white; outline: 2px solid var(--main-color); }

        .results-layout { display: grid; grid-template-columns: 1fr 360px; gap: 24px; margin-top: 25px; }

        .step-item { border-left: 6px solid var(--secondary-color); background: #fff; padding: 25px; margin-bottom: 20px; border: 1px solid var(--border-color); }
        .step-title { font-weight: bold; color: var(--main-color); margin-bottom: 10px; display: block; text-transform: uppercase; font-size: 0.85rem; letter-spacing: 1px; }

        .visual-panel { display: flex; flex-direction: column; gap: 20px; }
        .graph-box { background: #fff; border: 1px solid var(--border-color); padding: 25px; text-align: center; }
        .graph-wrapper { position: relative; width: 100%; max-width: 280px; margin: 0 auto; }
        #graphSvg { width: 100%; height: auto; display: block; background: #fff; border: 1px solid #eee; overflow: visible; }

        .props-table { width: 100%; border-collapse: collapse; }
        .props-table td, .props-table th { padding: 12px 0; border-bottom: 1px solid #e2e8f0; text-align: left; vertical-align: top; }
        .props-table th { font-weight: bold; color: var(--color-gray); width: 60%; }
        .props-table td:last-child { text-align: right; font-family: 'Courier New', monospace; color: var(--main-color); font-weight: bold; }

        .final-badge { margin-top: 25px; padding: 30px; text-align: center; font-size: 1.6rem; font-weight: bold; border-radius: 4px; }
        .success { background: var(--color-light-green); border: 2px solid var(--color-green); color: var(--color-green-dark); }
        .fail { background: #fee2e2; border: 2px solid var(--color-error-dark); color: #991b1b; }

        .copy-btn { margin-top: 15px; background: none; border: 1px solid #ccc; padding: 6px 16px; border-radius: 4px; cursor: pointer; font-size: 0.85rem; font-weight: bold; }
        .copy-btn:hover, .copy-btn:focus { background: #eee; outline: 1px solid var(--color-dark); }

        .math-box { 
            font-family: serif; background: #f1f5f9; padding: 2px 8px; border-radius: 4px; font-weight: normal; 
            color: var(--color-dark); font-size: 1.05rem; display: inline-block; white-space: normal; word-break: break-word;
        }

        /* --- Textbook Math Notation (Vertical Fractions) --- */
        .math-frac {
            display: inline-flex;
            flex-direction: column;
            vertical-align: middle;
            text-align: center;
            font-size: 0.9em;
            line-height: 1.1;
            margin: 0 0.25em;
        }
        .math-frac .num {
            border-bottom: 1.5px solid currentColor;
            padding: 0 0.2em;
            display: block;
        }
        .math-frac .den {
            padding: 0 0.2em;
            display: block;
        }

        .text-center { text-align: center; }
        .visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

        .example-block { margin-bottom: 2rem; border-bottom: 1px dashed var(--border-color); padding-bottom: 1.5rem; }
        .example-block:last-child { border-bottom: none; }
        .demo-line { color: var(--color-gray); font-style: normal; margin: 10px 0; border-left: 3px solid var(--tertiary-background); padding-left: 15px; font-family: serif; }

        /* Sitemap Style for Other Tools */
        .sitemap-section { margin-bottom: 1rem; }
        .sitemap-section ul { list-style-type: none; padding-left: 0; }
        .sitemap-section li { margin-bottom: 0.75rem; }
        .sitemap-section a { text-decoration: none; color: #333; font-size: 1.1rem; }
        .sitemap-section a:hover { text-decoration: underline; color: var(--main-color); }

        @media (max-width: 900px) {
            .results-layout { grid-template-columns: 1fr; }
            .visual-panel { order: -1; }
            .card { padding: 25px 16px; }
            .input-group { flex-direction: column; }
            .btn-primary { width: 100%; }
            input[type="text"] { min-width: 100%; }
            h1 { font-size: 1.8rem; }
        }
         @media (max-width: 480px) {
            .final-badge { font-size: 1.25rem; padding: 20px 10px; }
            .step-item { padding: 15px; }
            h2 { font-size: 1.3rem; }
        }
        @media (max-width: 320px) {
            .articlecontainer { padding: 0 8px; }
            .card { padding: 20px 10px; }
            .info-section { padding-left: 12px; }
            h1 { font-size: 1.5rem; }
            .final-badge { font-size: 1.1rem; }
            .graph-wrapper { max-width: 230px; }
        }