/* Reset و پایه */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        :root {
            --primary: #0f766e;
            --secondary: #0d9488;
            --accent: #10b981;
            --light: #f0fdfa;
            --dark: #134e4a;
            --warning: #f59e0b;
            --danger: #ef4444;
            --gray: #6b7280;
            --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
            --radius: 12px;
            --transition: all 0.3s ease;
        }

        body {
            background: linear-gradient(135deg, #f0fdfa 0%, #ccfbf1 100%);
            color: var(--dark);
            min-height: 100vh;
            padding: 20px;
        }

        .container {
            max-width: 1400px;
            margin: 0 auto;
            padding: 0 15px;
        }

        /* هدر */
        .header {
            background: white;
            border-radius: var(--radius);
            padding: 25px 30px;
            margin-bottom: 30px;
            box-shadow: var(--shadow);
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 20px;
        }

        .logo {
            display: flex;
            align-items: center;
            gap: 15px;
        }

        .logo i {
            font-size: 2.5rem;
            color: var(--primary);
        }

        .logo h1 {
            font-size: 1.8rem;
            color: var(--dark);
        }

        .logo span {
            color: var(--accent);
            font-weight: 600;
        }

        /* آزمایش‌ها */
        .experiments-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 20px;
            margin-bottom: 40px;
        }

        .experiment-card {
            background: white;
            border-radius: var(--radius);
            padding: 20px;
            box-shadow: var(--shadow);
            cursor: pointer;
            transition: var(--transition);
            border: 3px solid transparent;
            display: flex;
            flex-direction: column;
            gap: 15px;
        }

        .experiment-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
            border-color: var(--accent);
        }

        .experiment-card.active {
            border-color: var(--primary);
            background: linear-gradient(135deg, #f0fdfa, #dcfce7);
        }

        .card-header {
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .card-icon {
            width: 50px;
            height: 50px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            color: white;
        }

        .card-title {
            font-size: 1.1rem;
            font-weight: 600;
            color: var(--dark);
            line-height: 1.4;
        }

        .card-desc {
            color: var(--gray);
            font-size: 0.9rem;
            line-height: 1.5;
            height: 60px;
            overflow: hidden;
        }

        .card-tags {
            display: flex;
            gap: 8px;
            flex-wrap: wrap;
        }

        .tag {
            background: var(--light);
            color: var(--primary);
            padding: 4px 12px;
            border-radius: 50px;
            font-size: 0.8rem;
            font-weight: 500;
        }

        /* بخش محتوای آزمایش */
        .content-section {
            background: white;
            border-radius: var(--radius);
            padding: 30px;
            box-shadow: var(--shadow);
            display: none;
            animation: fadeIn 0.5s ease;
        }

        .content-section.active {
            display: block;
        }

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .content-header {
            margin-bottom: 30px;
            padding-bottom: 20px;
            border-bottom: 2px solid var(--light);
        }

        .content-header h1 {
            color: var(--primary);
            font-size: 2rem;
            margin-bottom: 10px;
            display: flex;
            align-items: center;
            gap: 15px;
        }

        .content-header h1 i {
            font-size: 2.5rem;
        }

        .content-header p {
            color: var(--gray);
            font-size: 1.1rem;
            line-height: 1.6;
        }

        /* تب‌ها */
        .tabs {
            display: flex;
            gap: 5px;
            margin-bottom: 30px;
            border-bottom: 2px solid var(--light);
            padding-bottom: 5px;
            flex-wrap: wrap;
        }

        .tab {
            padding: 12px 24px;
            background: white;
            border: 1px solid var(--light);
            border-radius: 8px 8px 0 0;
            cursor: pointer;
            transition: var(--transition);
            font-weight: 500;
            color: var(--gray);
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .tab:hover {
            background: var(--light);
            color: var(--primary);
        }

        .tab.active {
            background: var(--primary);
            color: white;
            border-color: var(--primary);
        }

        .tab-content {
            display: none;
            animation: slideIn 0.5s ease;
        }

        .tab-content.active {
            display: block;
        }

        @keyframes slideIn {
            from { opacity: 0; transform: translateX(-20px); }
            to { opacity: 1; transform: translateX(0); }
        }

        /* استایل محتوا */
        .formula-section {
            background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
            border-radius: var(--radius);
            padding: 25px;
            margin-bottom: 25px;
        }

        .formula-item {
            background: white;
            border-radius: 10px;
            padding: 20px;
            margin-bottom: 20px;
            border-left: 4px solid var(--accent);
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
        }

        .formula-display {
            font-size: 1.4rem;
            text-align: center;
            margin: 20px 0;
            padding: 20px;
            background: #f8fafc;
            border-radius: 8px;
            direction: ltr;
            font-family: 'Cambria Math', serif;
        }

        .variables-list {
            margin-top: 20px;
            padding-top: 20px;
            border-top: 1px dashed #cbd5e1;
        }

        .variable {
            display: flex;
            justify-content: space-between;
            padding: 8px 0;
            color: var(--dark);
            border-bottom: 1px solid #f1f5f9;
        }

        .variable:last-child {
            border-bottom: none;
        }

        .variable-name {
            font-weight: 600;
            color: var(--primary);
            font-family: 'Courier New', monospace;
        }

        /* روش انجام */
        .method-section {
            background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
            border-radius: var(--radius);
            padding: 25px;
        }

        .steps-list {
            list-style-type: none;
            counter-reset: step-counter;
        }

        .step-item {
            margin-bottom: 20px;
            padding-right: 50px;
            position: relative;
            line-height: 1.6;
            color: var(--dark);
            background: white;
            padding: 20px;
            border-radius: 8px;
            border-right: 4px solid var(--accent);
        }

        .step-item:before {
            counter-increment: step-counter;
            content: counter(step-counter);
            position: absolute;
            right: 15px;
            top: 50%;
            transform: translateY(-50%);
            background: var(--primary);
            color: white;
            width: 35px;
            height: 35px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: bold;
            font-size: 1.1rem;
        }

        /* پرسش و پاسخ */
        .faq-section {
            background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
            border-radius: var(--radius);
            padding: 25px;
        }

        .faq-item {
            background: white;
            border-radius: 10px;
            padding: 20px;
            margin-bottom: 15px;
            cursor: pointer;
            transition: var(--transition);
            border: 2px solid transparent;
        }

        .faq-item:hover {
            border-color: var(--accent);
            transform: translateX(-5px);
        }

        .faq-question {
            color: var(--primary);
            font-weight: 600;
            font-size: 1.1rem;
            display: flex;
            align-items: center;
            gap: 10px;
            margin-bottom: 10px;
        }

        .faq-answer {
            color: var(--dark);
            line-height: 1.6;
            display: none;
            padding-right: 30px;
            animation: fadeInUp 0.3s ease;
        }

        .faq-item.active .faq-answer {
            display: block;
        }

        .faq-item.active .faq-question i {
            transform: rotate(180deg);
        }

        .faq-question i {
            transition: var(--transition);
        }

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

        /* پاورقی */
        .footer {
            text-align: center;
            color: var(--gray);
            padding: 30px 0;
            margin-top: 40px;
            border-top: 1px solid #e5e7eb;
        }

        /* رسپانسیو */
        @media (max-width: 768px) {
            .experiments-grid {
                grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            }
            
            .content-header h1 {
                font-size: 1.6rem;
            }
            
            .tab {
                padding: 10px 15px;
                font-size: 0.9rem;
            }
            
            .step-item {
                padding-right: 45px;
            }
        }

        @media (max-width: 480px) {
            .experiments-grid {
                grid-template-columns: 1fr;
            }
            
            .header {
                flex-direction: column;
                text-align: center;
            }
        }