:root {
            --color-primary: #2563EB; --color-secondary: #F3F4F6; --color-dark: #111827;
            --color-light-bg: #F9FAFB; --color-success: #10B981; --color-danger: #EF4444;
            --color-card-bg: #FFFFFF; --color-input-bg: #FFFFFF; --color-border: #D1D5DB;
            --color-text-primary: #111827; --color-text-secondary: #4B5563;
            --spacing-xs: 4px; --spacing-sm: 8px; --spacing-md: 16px;
            --spacing-lg: 20px; --spacing-xl: 32px; --border-radius: 6px;
            --box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1); --transition: all 0.2s ease;
            --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
        }
        * { box-sizing: border-box; margin: 0; padding: 0; }
        body { font-family: var(--font-family); display: flex; flex-direction: column; min-height: 100vh; background-color: var(--color-light-bg); color: var(--color-text-primary); line-height: 1.5; font-size: 14px; }

        header { background: var(--color-primary); color: #fff; padding: 1.2rem 2.5rem; border-radius: 0; flex-shrink: 0; box-shadow: 0 2px 4px rgba(0,0,0,0.1); display: flex; align-items: center; justify-content: space-between; gap: var(--spacing-md); }
        .header-title { text-align: center; flex-grow: 1; }
        .header-title h1 { font-size: 2rem; margin-bottom: 2rem; }
        .header-title p { font-size: 0.85rem; opacity: 0.9; }
        .header-btn { background: rgba(255, 255, 255, 0.15); color: #fff; text-decoration: none; padding: 0.5rem 1.2rem; border-radius: var(--border-radius); font-weight: 600; font-size: 0.9rem; transition: var(--transition); white-space: nowrap; border: 1px solid rgba(255,255,255,0.3); cursor: pointer; }
        .header-btn:hover { background: rgba(255, 255, 255, 0.25); }

        #copyright { text-align: center; font-size: 12px; background-color: #FEE2E2; color: #991B1B; margin-bottom: var(--spacing-md); padding: 8px; border: 1px solid var(--color-border); border-radius: 3px; box-shadow: var(--box-shadow); }

        .app-container { display: flex; flex-grow: 1; overflow: hidden; }
        .left-panel { width: 420px; padding: var(--spacing-xl); background-color: var(--color-card-bg); box-shadow: 2px 0 5px rgba(0,0,0,0.1); overflow-y: auto; flex-shrink: 0; display: flex; flex-direction: column; border-right: 1px solid var(--color-border); }
        .right-panel { flex-grow: 1; position: relative; background-color: var(--color-light-bg); padding: var(--spacing-xl); overflow-y: auto; display: flex; flex-direction: column; }
        h2 { color: var(--color-text-primary); font-weight: 600; font-size: 1.2rem; margin-bottom: var(--spacing-lg); border-bottom: 2px solid var(--color-primary); padding-bottom: var(--spacing-sm); margin-top: 0; }

        .input-group { display: flex; flex-direction: column; margin-bottom: var(--spacing-md); }
        label { display: block; margin-bottom: var(--spacing-xs); font-weight: 500; color: var(--color-text-secondary); font-size: 0.875rem; }
        input[type="number"], select { width: 100%; padding: var(--spacing-sm) var(--spacing-md); border: 1px solid var(--color-border); border-radius: var(--border-radius); font-size: 1rem; transition: var(--transition); background-color: var(--color-input-bg); font-family: var(--font-family); }
        input:focus, select:focus { border-color: var(--color-primary); box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2); outline: none; }
        .input-row { display: grid; gap: var(--spacing-md); grid-template-columns: 1fr 1fr; }

        /* Кнопки режимов Выделить/Начислить */
        .mode-grid { display: grid; grid-template-columns: 1fr 1fr; gap: var(--spacing-sm); margin-bottom: var(--spacing-lg); }
        .mode-btn { width: 100%; padding: var(--spacing-md); border: 1px solid var(--color-border); border-radius: var(--border-radius); background-color: var(--color-card-bg); color: var(--color-text-secondary); font-size: 0.95rem; font-weight: 500; text-align: center; cursor: pointer; transition: var(--transition); }
        .mode-btn:hover { background-color: var(--color-secondary); }
        .mode-btn.active { background-color: var(--color-primary); color: white; border-color: var(--color-primary); box-shadow: 0 2px 6px rgba(37, 99, 235, 0.3); }

        .result-container { background-color: var(--color-card-bg); border-radius: 8px; box-shadow: var(--box-shadow); padding: var(--spacing-xl); border-top: 4px solid var(--color-primary); }
        .data-row { display: flex; justify-content: space-between; align-items: center; padding: var(--spacing-sm) 0; border-bottom: 1px solid var(--color-secondary); }
        .data-row:last-of-type { border-bottom: none; margin-bottom: var(--spacing-lg); }
        .data-label { color: var(--color-text-secondary); font-weight: 500; font-size: 0.9rem; }
        .data-value-group { display: flex; align-items: center; gap: var(--spacing-sm); }
        .data-val { font-weight: 700; font-size: 1.1rem; color: var(--color-dark); }
        .data-val.result-main { font-size: 1.6rem; color: var(--color-primary); }
        .copy-btn { width: auto; margin: 0; padding: 4px 10px; font-size: 0.75rem; font-weight: 600; background-color: transparent; color: var(--color-primary); border: 1px solid var(--color-border); border-radius: var(--border-radius); cursor: pointer; transition: var(--transition); }
        .copy-btn:hover { background-color: var(--color-secondary); border-color: var(--color-primary); }
        .explanation-box { background-color: var(--color-secondary); padding: var(--spacing-lg); border-radius: var(--border-radius); color: var(--color-text-secondary); font-size: 0.9rem; line-height: 1.7; margin-top: var(--spacing-lg); }
        .explanation-box strong { color: var(--color-dark); }
        .explanation-box .formula-highlight { color: var(--color-primary); font-weight: 600; }

        .modal-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(17, 24, 39, 0.6); backdrop-filter: blur(4px); display: flex; align-items: center; justify-content: center; z-index: 1000; }
        .modal-overlay.hidden { display: none; }
        .modal-box { background: var(--color-card-bg); width: 90%; max-width: 600px; border-radius: 8px; box-shadow: 0 10px 30px rgba(0,0,0,0.2); display: flex; flex-direction: column; max-height: 80vh; }
        .modal-header { padding: var(--spacing-lg); border-bottom: 1px solid var(--color-border); }
        .modal-header h2 { border: none; padding: 0; margin: 0; font-size: 1.3rem; }
        .modal-content { padding: var(--spacing-lg); overflow-y: auto; flex-grow: 1; font-size: 0.9rem; color: var(--color-text-secondary); line-height: 1.6; }
        .modal-content h3 { margin-top: var(--spacing-md); margin-bottom: var(--spacing-sm); color: var(--color-text-primary); font-size: 1rem; }
        .modal-footer { padding: var(--spacing-lg); border-top: 1px solid var(--color-border); display: flex; justify-content: flex-end; gap: var(--spacing-md); }
        .btn-modal { padding: var(--spacing-sm) var(--spacing-lg); border-radius: var(--border-radius); font-weight: 600; cursor: pointer; border: 1px solid var(--color-border); background: var(--color-secondary); color: var(--color-text-primary); transition: var(--transition); font-family: var(--font-family); }
        .btn-modal:hover { background: #e0e0e0; }
        .btn-modal.primary { background: var(--color-primary); color: white; border-color: var(--color-primary); }
        .btn-modal.primary:hover { background: #1D4ED8; }

        @media (max-width: 900px) {
            body { height: auto; overflow: auto; }
            .app-container { flex-direction: column; height: auto; overflow: auto; }
            .left-panel { width: 100%; box-shadow: none; border-right: none; border-bottom: 2px solid var(--color-border); }
            .input-row { grid-template-columns: 1fr; }
            .mode-grid { grid-template-columns: 1fr; }
            header { flex-direction: column; text-align: center; padding: 1rem; }
        }
		
		/* Стили для SEO описания */
        .seo-description {
            max-width: 900px;
            margin: 0 auto;
            padding: 40px 20px 60px;
            background-color: #fff;
        }
        .seo-description h2 {
            color: var(--color-dark);
            font-size: 1.8rem;
            margin-bottom: 20px;
            border-bottom: 2px solid var(--color-primary);
            padding-bottom: 10px;
        }
        .seo-description h3 {
            color: var(--color-primary);
            font-size: 1.2rem;
            margin-top: 30px;
            margin-bottom: 10px;
        }
        .seo-description p, .seo-description ul {
            font-size: 1rem;
            line-height: 1.7;
            color: var(--color-text-secondary);
            margin-bottom: 15px;
        }
        .seo-description ul {
            margin-left: 20px;
        }
        .seo-description li {
            margin-bottom: 8px;
        }
        .seo-description em {
            color: var(--color-dark);
            font-weight: 500;
            font-style: normal;
        }