.watermark-bg {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: 0;
            pointer-events: none;
            background-image: repeating-linear-gradient(45deg,
                    transparent,
                    transparent 60px,
                    rgba(0, 0, 0, 0.03) 60px,
                    rgba(0, 0, 0, 0.03) 61px);
        }

        /* ลายน้ำข้อความแบบซ้ำ */
        .watermark-text-layer {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: 0;
            pointer-events: none;
            background-image: repeating-linear-gradient(45deg,
                    transparent 0 50px,
                    rgba(0, 0, 0, 0.02) 50px 51px),
                repeating-linear-gradient(45deg,
                    rgba(0, 0, 0, 0.04) 0 0);
            background-size: 200px 200px;
        }

        .watermark-overlay {
            position: fixed;
            top: 0;
            left: 0;
            z-index: 0;
            width: 100%;
            height: 100%;
            pointer-events: none;
            background-image: url("data:image/svg+xml;charset=UTF-8,<svg xmlns='http://www.w3.org/2000/svg' width='150' height='200'> <text x='0' y='100' transform='rotate(-30 120 120)' fill='rgba(0,0,0,0.06)' font-size='18'>  RMUTT </text> </svg>");
            background-repeat: repeat;
        }