SVG with marker having an issue on mouse over - css

Question

I have a button with svg inside like:
<button>
Checkout
<ArrowSvg />
</button>
And ArrowSvg looks like this (line has class: svg-line):
<svg fill="none" stroke="#000">
<defs>
<marker id="m" overflow="visible">
<path d="M-4,-4L0,0 -4,4" />
</marker>
</defs>
<line x1="0" y1="50%" x2="100%" y2="50%"marker-end="url(#m)" class="svg-line" />
</svg>
When button is hovered, I change the stroke color:
btn:hover > .svg-line {
stroke: blue;
}
It's working well - when I hover the button, the arrow (line and arrow head) turns blue.
But when I display the multiple buttons (more than 1), hovering 1 button affects arrows in other buttons. The arrow head part (which is marker/path in svg?) of all the buttons get affected when hovering the first button.
I am also working with the arrow width, so I need line. I can't make everything with path because I won't be able to expand the arrow width.
Am I missing anything? Why am I seeing this issue?

Answer 1

Wrap it in a native JS Web Component, supported in all modern browsers, to create the <svg>
because every SVG requires a unique marker ID
note: the SVG is created for every instance, no need for a marker at all, use the path by itself
customElements.define("svg-button",class extends HTMLElement{
connectedCallback(){
let id = "id" + (Math.floor(Math.random() * 1e10));
let stroke = this.getAttribute("stroke") || "#000";
this.innerHTML = `
<button>
Checkout
<svg fill="none" stroke="${stroke}" viewBox="0 0 10 10">
<defs>
<marker id="${id}" overflow="visible">
<path d="M-4,-4L0,0 -4,4"/>
</marker>
</defs>
<line x1="0" y1="5" x2="9" y2="5" marker-end="url(#${id})"/>
</svg>
</button>`
}
});
<style>
button:hover svg {
stroke:gold;
}
</style>
<svg-button></svg-button>
<svg-button stroke="red"></svg-button>
<svg-button stroke="green"></svg-button>
<svg-button stroke="blue"></svg-button>

Answer 2

What you are writing looks like .JSX syntax, but the question is lacking a react tag. I will assume it for this answer anyway, but other frameworks using the format will probably work comparably.
All you need is a unique id for the <marker> element. This is easily done if you spell out the <ArrowSvg> as a function. Then, wrap it in a factory function to form a closure over a running number:
const ArrowSvg = (() => {
let id = 0;
return function (props) {
return (
const ref = 'arrowMarker' + ++id;
<svg fill="none" stroke="#000">
<defs>
<marker id=(ref) overflow="visible">
<path d="M-4,-4L0,0 -4,4" />
</marker>
</defs>
<line x1="0" y1="50%" x2="100%" y2="50%"
marker-end=(`url(#${ref})`) class="svg-line" />
</svg>
);
}
})();