:root {
            --bg: #f5f6f8;
            --panel: #ffffff;
            --text: #17191c;
            --muted: #626975;
            --line: #d9dde3;
            --accent: #da1d2a;
            --accent-dark: #a90f1b;
            --focus: #246bfe;
            --shadow: 0 18px 45px rgba(22, 28, 37, 0.09);
        }

        * {
            box-sizing: border-box;
        }

        body {
            margin: 0;
            min-height: 100vh;
            background: var(--bg);
            color: var(--text);
            font-family: Arial, Helvetica, sans-serif;
        }

        .app {
            width: min(1180px, calc(100% - 32px));
            margin: 0 auto;
            padding: 28px 0 36px;
        }

        .topbar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            gap: 16px;
            margin-bottom: 22px;
        }

        .brand {
            display: flex;
            align-items: center;
            gap: 12px;
            min-width: 0;
        }

        .brand img {
            width: 42px;
            height: 42px;
            object-fit: contain;
            background: #111;
            border-radius: 6px;
            padding: 5px;
        }

        h1 {
            margin: 0;
            font-size: 22px;
            line-height: 1.2;
            letter-spacing: 0;
        }

        .status {
            min-height: 20px;
            color: var(--muted);
            font-size: 13px;
            text-align: right;
        }

        .workspace {
            display: grid;
            grid-template-columns: minmax(300px, 430px) minmax(0, 1fr);
            gap: 20px;
            align-items: start;
        }

        .panel {
            background: var(--panel);
            border: 1px solid var(--line);
            border-radius: 8px;
            box-shadow: var(--shadow);
        }

        .form-panel {
            padding: 18px;
        }

        .section-title {
            margin: 2px 0 14px;
            font-size: 14px;
            font-weight: 700;
            color: var(--text);
        }

        .field-grid {
            display: grid;
            gap: 12px;
        }

        .field {
            display: grid;
            gap: 6px;
        }

        .field.two {
            grid-template-columns: 1fr 1fr;
            gap: 12px;
        }

        label {
            color: var(--muted);
            font-size: 12px;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 0;
        }

        input {
            width: 100%;
            min-height: 40px;
            border: 1px solid var(--line);
            border-radius: 6px;
            padding: 9px 10px;
            color: var(--text);
            background: #fff;
            font: 14px Arial, Helvetica, sans-serif;
        }

        input:focus {
            border-color: var(--focus);
            outline: 2px solid rgba(36, 107, 254, 0.16);
            outline-offset: 0;
        }

        .actions {
            display: grid;
            grid-template-columns: 1fr;
            gap: 10px;
            margin-top: 16px;
        }

        button {
            min-height: 42px;
            border: 1px solid transparent;
            border-radius: 6px;
            padding: 9px 12px;
            font: 700 14px Arial, Helvetica, sans-serif;
            cursor: pointer;
        }

        .primary {
            background: var(--accent);
            color: #fff;
        }

        .primary:hover {
            background: var(--accent-dark);
        }

        .secondary {
            background: #fff;
            color: var(--text);
            border-color: var(--line);
        }

        .secondary:hover {
            border-color: #aeb5bf;
            background: #fafafa;
        }

        .preview-panel {
            overflow: hidden;
        }

        .preview-head {
            display: flex;
            align-items: center;
            justify-content: space-between;
            gap: 14px;
            padding: 14px 16px;
            border-bottom: 1px solid var(--line);
        }

        .preview-head h2 {
            margin: 0;
            font-size: 14px;
            letter-spacing: 0;
        }

        .preview-shell {
            min-height: 230px;
            padding: 26px;
            overflow: auto;
            background:
                linear-gradient(90deg, rgba(217, 221, 227, 0.38) 1px, transparent 1px),
                linear-gradient(rgba(217, 221, 227, 0.38) 1px, transparent 1px);
            background-size: 18px 18px;
        }

        .signature-preview {
            display: inline-block;
            background: #fff;
            border: 1px solid #edf0f3;
            padding: 16px;
        }

        .fallback-box {
            position: fixed;
            left: -9999px;
            top: 0;
            width: 600px;
            background: #fff;
        }

        @media (max-width: 860px) {
            .workspace {
                grid-template-columns: 1fr;
            }

            .topbar {
                align-items: flex-start;
                flex-direction: column;
            }

            .status {
                text-align: left;
            }
        }

        @media (max-width: 520px) {
            .app {
                width: min(100% - 20px, 1180px);
                padding-top: 16px;
            }

            .field.two,
            .actions {
                grid-template-columns: 1fr;
            }

            .preview-shell {
                padding: 14px;
            }
        }