responsive CCS for Desktop and Mobile

I am trying to write a CSS file to change a grid based on the screen size but the code I have below does not work, when viewed on a desktop it always uses the last option "@media screen and (max-width: 480px)" and dont understand why?

/* Masonry Grid Styles */
.cmg-grid {
display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 20px;
}

.cmg-grid-item {
background-color: #f9f9f9;
border-radius: 8px;
overflow: hidden;
box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.cmg-thumbnail img {
width: 100%;
height: auto;
}

.cmg-excerpt {
padding: 15px;
}

.cmg-excerpt h2 {
font-size: 18px;
margin: 0;
padding-bottom: 10px;
}

.cmg-excerpt p {
font-size: 14px;
margin: 0 0 15px;
color: #555;
}

.cmg-read-more {
display: inline-block;
background-color: #007bff;
color: white;
padding: 10px 15px;
text-decoration: none;
border-radius: 4px;
}

.cmg-read-more:hover {
background-color: #0056b3;
}

/* Responsive Design */
@media screen and (max-width: 768px) {
.cmg-grid {
grid-template-columns: repeat(2, 1fr);
}
}

@media screen and (max-width: 480px) {
.cmg-grid {
grid-template-columns: 1fr;
}
}

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