html, body {
    height: 100%;
}

.landing-bg {
    position: relative; /* BẮT BUỘC */
    min-height: 100vh;
    width: 100%;
    background-image: url("/images/bg.jpg");
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
}

    .landing-bg::before {
        content: "";
        position: absolute;
        inset: 0;
        backdrop-filter: blur(6px);     /* 👈 BLUR */
        background: rgba(0,0,0,0.25);   /* overlay */
        z-index: 0;
    }

    .landing-bg > * {
        position: relative;
        z-index: 1;
    }