Framebuffer quad problem on window resize

Question

I'm following a tutorial on learnOpenGL site regarding Framebuffers which work fine at default resolution.

But whenever I resize my window, the framebuffer quad gets offset terribly. For instance if I expand the window bigger the framebuffer looks zoomed in and if I shrink my window there's gaps on the top and right. Here is a screenshot with 1 as default window, 2 as stretched big and 3 shrunk down after resize:

I did read that I have to call glViewport again but where exactly do I call this? This is my framebuffer callback I've been using:

void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    glViewport(0, 0, width, height);
}

And my framebuffer creation in main:

// configure framebuffer here //
unsigned int hdrFBO;
glGenFramebuffers(1, &hdrFBO);
glBindFramebuffer(GL_FRAMEBUFFER, hdrFBO);
// create color attachment texture buffer
unsigned int colorBuffer;
glGenTextures(1, &colorBuffer);
glBindTexture(GL_TEXTURE_2D, colorBuffer);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, width, height, 0, GL_RGBA, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorBuffer, 0);
    
// create depth buffer (renderbuffer) 
unsigned int rboDepth;
glViewport(0, 0, width, height);
glGenRenderbuffers(1, &rboDepth);
glBindRenderbuffer(GL_RENDERBUFFER, rboDepth);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepth);
// check status
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    std::cout << "Framebuffer not complete!" << std::endl;
glBindFramebuffer(GL_FRAMEBUFFER, 0);

Is there a simple way to fix this?