Split

<div class="btn-split">
  <button class="btn-split__trigger" type="button">
    <span>Save</span>
  </button>
  <button class="btn-split__trigger" type="button" aria-expanded="false" aria-label="More actions">
    <svg class="btn-split__icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
      <path d="m6 9 6 6 6-6"></path>
    </svg>
  </button>
  <div class="btn-split__menu" hidden>
    <button class="btn-split__item" type="button">Edit</button>
    <button class="btn-split__item" type="button">Duplicate</button>
  </div>
</div>

.btn-split {
  --btn-bg: #7c5cff;
  --btn-fg: #ffffff;
  --btn-font: inherit;
  --btn-size: 15px;
  --btn-weight: 600;
  --btn-px: 18px;
  --btn-py: 11px;
  --btn-w: auto;
  --btn-h: auto;
  --btn-bw: 0px;
  --btn-line: #8b6cff;
  --btn-radius: 10px;
  --btn-shadow: none;
  --btn-speed: 180ms;
}

.btn-split__trigger {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  box-sizing: border-box;
  width: var(--btn-w);
  height: var(--btn-h);
  padding: var(--btn-py) var(--btn-px);
  font-family: var(--btn-font);
  font-size: var(--btn-size);
  font-weight: var(--btn-weight);
  line-height: 1.2;
  color: var(--btn-fg);
  background: var(--btn-bg);
  border: var(--btn-bw) solid var(--btn-line);
  border-radius: var(--btn-radius);
  box-shadow: var(--btn-shadow);
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  transition: all var(--btn-speed) ease;
}

.btn-split__trigger:focus-visible {
  outline: 2px solid var(--btn-bg);
  outline-offset: 2px;
}

.btn-split__trigger:disabled {
  opacity: 0.5;
  pointer-events: none;
}

.btn-split__icon {
  width: 1.15em;
  height: 1.15em;
  flex-shrink: 0;
}

.btn-split {
  position: relative;
  display: inline-flex;
  gap: 1px;
}

.btn-split__menu {
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  z-index: 10;
  display: grid;
  gap: 2px;
  min-width: 100%;
  box-sizing: border-box;
  padding: 4px;
  background: #1f1f28;
  border: 1px solid #33333f;
  border-radius: 10px;
  box-shadow: 0 10px 24px rgba(0,0,0,.35);
}

.btn-split__menu[hidden] {
  display: none;
}

.btn-split__item {
  padding: 7px 10px;
  font-family: inherit;
  font-size: 14px;
  color: #f4f4f6;
  background: transparent;
  border: 0;
  border-radius: 6px;
  text-align: left;
  cursor: pointer;
}

.btn-split__item:hover {
  background: #33333f;
}

.btn-split__item:focus-visible {
  background: #33333f;
  outline: none;
}

.btn-split__trigger:first-of-type {
  border-radius: var(--btn-radius) 0 0 var(--btn-radius);
}

.btn-split__trigger:last-of-type {
  padding: var(--btn-py) 10px;
  border-radius: 0 var(--btn-radius) var(--btn-radius) 0;
}

@media (prefers-reduced-motion: reduce) {
  .btn-split__trigger {
    animation: none !important;
    transition: none !important;
  }
}

document.querySelectorAll(".btn-split").forEach((el) => {
  const trigger = el.querySelector("[aria-expanded]");
  const list = el.querySelector("[hidden]");
  const set = (open) => {
    list.hidden = !open;
    trigger.setAttribute("aria-expanded", String(open));
  };
  const flip = () => set(list.hidden);
  const picked = () => {
    set(false);
    trigger.focus();
  };
  const key = (e) => {
    if (e.key === "Escape" && !list.hidden) picked();
  };
  const away = (e) => {
    if (!e.composedPath().includes(el)) set(false);
  };
  trigger.addEventListener("click", flip);
  list.addEventListener("click", picked);
  el.addEventListener("keydown", key);
  document.addEventListener("click", away);
  return () => {
    trigger.removeEventListener("click", flip);
    list.removeEventListener("click", picked);
    el.removeEventListener("keydown", key);
    document.removeEventListener("click", away);
  };
});

import { useEffect, useRef } from "react";
import type React from "react";
import "./split.css"; // the CSS tab

function attach(el: HTMLElement) {
  const trigger = el.querySelector("[aria-expanded]") as HTMLElement;
  const list = el.querySelector("[hidden]") as HTMLElement;
  const set = (open: boolean) => {
    list.hidden = !open;
    trigger.setAttribute("aria-expanded", String(open));
  };
  const flip = () => set(list.hidden);
  const picked = () => {
    set(false);
    trigger.focus();
  };
  const key = (e: KeyboardEvent) => {
    if (e.key === "Escape" && !list.hidden) picked();
  };
  const away = (e: Event) => {
    if (!e.composedPath().includes(el)) set(false);
  };
  trigger.addEventListener("click", flip);
  list.addEventListener("click", picked);
  el.addEventListener("keydown", key);
  document.addEventListener("click", away);
  return () => {
    trigger.removeEventListener("click", flip);
    list.removeEventListener("click", picked);
    el.removeEventListener("keydown", key);
    document.removeEventListener("click", away);
  };
}

export function BtnSplit({ children = "Save", ...props }: React.ComponentProps<"div">) {
  const ref = useRef<HTMLDivElement>(null);
  useEffect(() => attach(ref.current!), []);

  return (
    <div className="btn-split" ref={ref} {...props}>
      <button className="btn-split__trigger" type="button">
        <span>{children}</span>
      </button>
      <button className="btn-split__trigger" type="button" aria-expanded="false" aria-label="More actions">
        <svg className="btn-split__icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="m6 9 6 6 6-6" />
        </svg>
      </button>
      <div className="btn-split__menu" hidden>
        <button className="btn-split__item" type="button">{"Edit"}</button>
        <button className="btn-split__item" type="button">{"Duplicate"}</button>
      </div>
    </div>
  );
}

<div class="btn-split relative inline-flex gap-[1px]">
  <button class="relative inline-flex items-center justify-center gap-[0.5em] [box-sizing:border-box] [padding:11px_18px] [font-family:inherit] text-[15px] font-[600] [line-height:1.2] text-[#ffffff] bg-[#7c5cff] [border:0px_solid_#8b6cff] rounded-[10px] [box-shadow:none] cursor-pointer no-underline whitespace-nowrap [transition:all_180ms_ease] focus-visible:[outline:2px_solid_#7c5cff] focus-visible:[outline-offset:2px] disabled:[opacity:0.5] disabled:[pointer-events:none] [&:first-of-type]:rounded-[10px_0_0_10px] [&:last-of-type]:[padding:11px_10px] [&:last-of-type]:rounded-[0_10px_10px_0] motion-reduce:[transition:none!important]" type="button">
    <span>Save</span>
  </button>
  <button class="relative inline-flex items-center justify-center gap-[0.5em] [box-sizing:border-box] [padding:11px_18px] [font-family:inherit] text-[15px] font-[600] [line-height:1.2] text-[#ffffff] bg-[#7c5cff] [border:0px_solid_#8b6cff] rounded-[10px] [box-shadow:none] cursor-pointer no-underline whitespace-nowrap [transition:all_180ms_ease] focus-visible:[outline:2px_solid_#7c5cff] focus-visible:[outline-offset:2px] disabled:[opacity:0.5] disabled:[pointer-events:none] [&:first-of-type]:rounded-[10px_0_0_10px] [&:last-of-type]:[padding:11px_10px] [&:last-of-type]:rounded-[0_10px_10px_0] motion-reduce:[transition:none!important]" type="button" aria-expanded="false" aria-label="More actions">
    <svg class="w-[1.15em] h-[1.15em] [flex-shrink:0]" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
      <path d="m6 9 6 6 6-6"></path>
    </svg>
  </button>
  <div class="absolute [top:calc(100%_+_6px)] [left:0] [z-index:10] grid gap-[2px] [min-width:100%] [box-sizing:border-box] [padding:4px] bg-[#1f1f28] [border:1px_solid_#33333f] rounded-[10px] [box-shadow:0_10px_24px_rgba(0,0,0,.35)] [&[hidden]]:hidden" hidden>
    <button class="[padding:7px_10px] [font-family:inherit] text-[14px] text-[#f4f4f6] [background:transparent] [border:0] rounded-[6px] [text-align:left] cursor-pointer hover:bg-[#33333f] focus-visible:bg-[#33333f] focus-visible:[outline:none]" type="button">Edit</button>
    <button class="[padding:7px_10px] [font-family:inherit] text-[14px] text-[#f4f4f6] [background:transparent] [border:0] rounded-[6px] [text-align:left] cursor-pointer hover:bg-[#33333f] focus-visible:bg-[#33333f] focus-visible:[outline:none]" type="button">Duplicate</button>
  </div>
</div>

<!-- Needs the script from the JS tab. -->