body.page-useful .useful-container {
            padding: 40px 5%;
            min-height: calc(100vh - 200px);
        }

        body.page-useful .useful-title {
            font-size: 2.2rem;
            color: var(--text-primary);
            margin-bottom: 30px;
            display: flex;
            align-items: center;
            gap: 15px;
            padding-bottom: 15px;
            border-bottom: 2px solid rgba(0, 90, 156, 0.3);
        }

        body.page-useful .useful-title i {
            background: linear-gradient(135deg, var(--primary-blue), var(--accent-teal));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        body.page-useful .materials-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
            gap: 15px;
            margin-top: 30px;
        }

        body.page-useful .material-card {
            background: var(--gradient-card);
            border-radius: 12px;
            padding: 30px;
            transition: all 0.3s ease;
            border: 1px solid rgba(0, 90, 156, 0.2);
            cursor: pointer;
            position: relative;
            overflow: hidden;
        }

        @media (max-width: 640px) {
            body.page-useful .useful-container {
                padding: 18px 12px 28px;
            }

            body.page-useful .useful-title {
                font-size: 1.45rem;
                gap: 9px;
                margin-bottom: 16px;
                padding-bottom: 9px;
            }

            body.page-useful .materials-grid {
                grid-template-columns: 1fr;
                gap: 10px;
                margin-top: 16px;
            }

            body.page-useful .material-card {
                padding: 17px 14px;
            }
        }

        body.page-useful .material-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(0, 200, 255, 0.1), transparent);
            transition: left 0.6s ease;
        }

        body.page-useful .material-card:hover::before {
            left: 100%;
        }

        body.page-useful .material-card:hover {
            transform: translateY(-5px);
            border-color: var(--secondary-blue);
            box-shadow: var(--shadow);
        }

        body.page-useful .material-icon {
            width: 70px;
            height: 70px;
            background: rgba(0, 90, 156, 0.2);
            border-radius: 15px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-bottom: 20px;
            color: var(--secondary-blue);
            font-size: 2rem;
            transition: all 0.3s ease;
        }

        body.page-useful .material-card:hover .material-icon {
            background: rgba(0, 90, 156, 0.4);
            transform: scale(1.05);
        }

        body.page-useful .material-title {
            font-size: 1.3rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 15px;
        }

        body.page-useful .material-description {
            color: var(--text-secondary);
            font-size: 0.95rem;
            line-height: 1.6;
            margin-bottom: 20px;
        }

        body.page-useful .material-meta {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding-top: 15px;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            color: var(--text-secondary);
            font-size: 0.9rem;
        }

        body.page-useful .material-meta i {
            color: var(--primary-blue);
            margin-right: 5px;
        }

        body.page-useful .download-btn {
            margin-top: 20px;
            background: transparent;
            border: 1px solid var(--primary-blue);
            color: var(--text-primary);
            padding: 8px 15px;
            border-radius: 6px;
            font-size: 0.9rem;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        body.page-useful .download-btn:hover {
            background: var(--primary-blue);
            color: white;
        }

        body.page-useful .useful-search {
            max-width: 600px;
            margin: 30px auto 40px;
            position: relative;
        }

        body.page-useful .useful-search input {
            width: 100%;
            padding: 15px 20px 15px 50px;
            background: var(--bg-card);
            border: 2px solid rgba(0, 90, 156, 0.3);
            border-radius: 50px;
            color: var(--text-primary);
            font-size: 1rem;
            transition: all 0.3s ease;
        }

        body.page-useful .useful-search input:focus {
            outline: none;
            border-color: var(--primary-blue);
            box-shadow: 0 0 0 3px rgba(0, 90, 156, 0.1);
        }

        body.page-useful .useful-search i {
            position: absolute;
            left: 20px;
            top: 50%;
            transform: translateY(-50%);
            color: var(--text-secondary);
            font-size: 1.2rem;
        }

        body.page-useful .categories {
            display: flex;
            gap: 15px;
            margin-bottom: 30px;
            flex-wrap: wrap;
            justify-content: center;
        }

        body.page-useful .category-btn {
            padding: 10px 25px;
            background: var(--bg-card);
            border: 1px solid rgba(0, 90, 156, 0.3);
            color: var(--text-secondary);
            border-radius: 30px;
            cursor: pointer;
            transition: all 0.3s ease;
            font-weight: 600;
            font-size: 0.95rem;
        }

        body.page-useful .category-btn:hover {
            border-color: var(--secondary-blue);
            color: var(--text-primary);
            transform: translateY(-2px);
        }

        body.page-useful .category-btn.active {
            background: var(--primary-blue);
            color: var(--white);
            border-color: var(--primary-blue);
        }