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

        body {
            background: #f5f5f5;
            font-family: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            padding: 2rem 1.5rem;
            color: #222;
        }

        .container {
            max-width: 1000px;
            margin: 0 auto;
        }

        /* brand header */
        .brand {
            margin-bottom: 1.5rem;
            display: flex;
            align-items: baseline;
            gap: 0.75rem;
            flex-wrap: wrap;
        }

        .brand h1 {
            font-weight: 450;
            font-size: 1.8rem;
            letter-spacing: -0.02em;
            color: #2a2a2a;
        }

        .brand .centrigon {
            font-weight: 500;
            color: #6b4f3f;
            background: #ede8e3;
            padding: 0.2rem 0.8rem;
            border-radius: 40px;
            font-size: 0.9rem;
        }

        .brand .tagline {
            color: #777;
            font-size: 0.95rem;
            font-weight: 350;
        }

        /* navigation between tools */
        .nav-links {
            display: flex;
            gap: 1rem;
            margin-bottom: 2rem;
            background: white;
            padding: 0.6rem 1.2rem;
            border-radius: 60px;
            border: 1px solid #e0e0e0;
            width: fit-content;
            flex-wrap: wrap;
        }

        .nav-links a {
            text-decoration: none;
            color: #555;
            font-size: 0.95rem;
            padding: 0.3rem 1rem;
            border-radius: 30px;
            cursor: pointer;
        }

        .nav-links a.active {
            background: #222;
            color: white;
        }

        .nav-links a:hover {
            background: #f0f0f0;
            color: #222;
        }

        /* input area */
        .input-block {
            background: white;
            border-radius: 16px;
            padding: 1.5rem;
            margin-bottom: 2rem;
            border: 1px solid #e0e0e0;
        }

        .input-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 1rem;
            font-size: 0.9rem;
            color: #666;
        }

        textarea {
            width: 100%;
            padding: 1rem;
            font-size: 1.2rem;
            border: 1px solid #ccc;
            border-radius: 12px;
            font-family: inherit;
            resize: vertical;
            min-height: 200px;
        }

        textarea:focus {
            outline: none;
            border-color: #888;
        }

        /* stats dashboard */
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
            gap: 1rem;
            margin: 1.5rem 0;
        }

        .stat-card {
            background: #fafafa;
            border: 1px solid #e0e0e0;
            border-radius: 16px;
            padding: 1.2rem 1rem;
            text-align: center;
            transition: 0.1s;
        }

        .stat-card:hover {
            background: white;
            border-color: #bbb;
        }

        .stat-value {
            font-size: 2.5rem;
            font-weight: 400;
            line-height: 1.2;
            color: #2a2a2a;
        }

        .stat-label {
            font-size: 0.85rem;
            text-transform: uppercase;
            letter-spacing: 0.5px;
            color: #777;
            margin-top: 0.3rem;
        }

        .stat-trend {
            font-size: 0.8rem;
            color: #999;
            margin-top: 0.3rem;
        }

        /* reading time specific */
        .reading-time-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 1rem;
            margin: 1.5rem 0;
        }

        .time-card {
            background: #fafafa;
            border: 1px solid #e0e0e0;
            border-radius: 16px;
            padding: 1rem;
            text-align: center;
        }

        .time-value {
            font-size: 2rem;
            font-weight: 400;
            color: #2a2a2a;
        }

        .time-label {
            font-size: 0.8rem;
            color: #777;
            margin-top: 0.2rem;
        }

        .time-note {
            font-size: 0.7rem;
            color: #999;
            margin-top: 0.3rem;
        }

        /* keyword density section */
        .keywords-section {
            background: #fafafa;
            border: 1px solid #e0e0e0;
            border-radius: 16px;
            padding: 1.5rem;
            margin: 1.5rem 0;
        }

        .section-title {
            font-size: 1rem;
            font-weight: 500;
            color: #444;
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .keyword-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 0.8rem;
        }

        .keyword-item {
            background: white;
            border: 1px solid #e0e0e0;
            border-radius: 40px;
            padding: 0.5rem 1rem;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .keyword-word {
            font-weight: 500;
            color: #333;
        }

        .keyword-count {
            background: #f0f0f0;
            padding: 0.2rem 0.8rem;
            border-radius: 30px;
            font-size: 0.8rem;
            color: #666;
        }

        .keyword-bar {
            width: 60px;
            height: 6px;
            background: #e0e0e0;
            border-radius: 3px;
            overflow: hidden;
        }

        .keyword-bar-fill {
            height: 100%;
            background: #6b4f3f;
            border-radius: 3px;
        }

        /* additional metrics */
        .metrics-grid {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 1rem;
            margin: 1rem 0;
        }

        .metric-item {
            background: white;
            border: 1px solid #e0e0e0;
            border-radius: 12px;
            padding: 0.8rem;
            text-align: center;
        }

        .metric-value {
            font-size: 1.3rem;
            font-weight: 500;
            color: #2a2a2a;
        }

        .metric-label {
            font-size: 0.7rem;
            color: #777;
            text-transform: uppercase;
            margin-top: 0.2rem;
        }

        /* quick actions */
        .quick-actions {
            display: flex;
            gap: 0.5rem;
            margin-top: 1rem;
            flex-wrap: wrap;
        }

        .quick-btn {
            background: #f0f0f0;
            border: 1px solid #ddd;
            padding: 0.5rem 1rem;
            border-radius: 30px;
            font-size: 0.9rem;
            cursor: pointer;
            transition: 0.1s;
        }

        .quick-btn:hover {
            background: #e0e0e0;
        }

        .toast {
            position: fixed;
            bottom: 30px;
            right: 30px;
            background: #222;
            color: white;
            padding: 0.6rem 1.5rem;
            border-radius: 40px;
            font-size: 0.9rem;
            opacity: 0;
            transition: opacity 0.15s;
            pointer-events: none;
            z-index: 1000;
        }

        .footer {
            margin-top: 3rem;
            text-align: center;
            color: #888;
            font-size: 0.8rem;
            border-top: 1px solid #ddd;
            padding-top: 2rem;
        }

        /* readability score */
        .readability-score {
            display: inline-block;
            background: #ede8e3;
            padding: 0.3rem 1rem;
            border-radius: 40px;
            font-size: 0.9rem;
            color: #5a4a3e;
        }

        #export-options {
            justify-content: flex-end;
        }