Signal Disc — Back to Top Button

Source Code

Copy the HTML, CSS or JavaScript you need for your project.

<!-- TB-2051 / Signal Disc | paste before closing body -->
<button class="backtop tb-btt-button w2051" type="button" aria-label="Back to top"><span class="w51arc"></span><span class="w51stem">↑</span><span class="w51name">TOP</span></button>

/* TB-2051 / Signal Disc */
.backtop{box-sizing:border-box;position:fixed;z-index:50;cursor:pointer;opacity:0;visibility:hidden;pointer-events:none;transform:translateY(12px);text-align:center;transition:opacity .24s, transform .28s, visibility .24s}.backtop.is-visible{opacity:1;visibility:visible;pointer-events:auto;transform:translateY(0)}.backtop.w2055.is-visible{transform:translate(-50%,0)}.backtop:focus-visible{outline:3px solid #e7ab4c;outline-offset:4px}
.w2051{right:27px;bottom:27px;width:72px;height:72px;border-radius:50%;background:#d75235;color:#fff;border:0;box-shadow:0 9px 28px #693a303d}.w51arc{position:absolute;inset:7px;border:1px solid #ffffff94;border-radius:50%;transform:scale(.99);transition:transform .32s,border-color .32s}.w51stem{position:absolute;top:11px;left:0;width:100%;font:400 31px/1 Georgia,serif;transition:transform .32s}.w51name{position:absolute;bottom:15px;left:0;right:0;font:700 9px Arial,sans-serif;letter-spacing:.15em}.w2051:hover .w51arc{transform:scale(1.12);border-color:#fff}.w2051:hover .w51stem{transform:translateY(-4px)}
@media(prefers-reduced-motion:reduce){*,*:before,*:after{transition-duration:.01ms!important;animation-duration:.01ms!important}}
/* POLISH PASS 2026-10-18: alignment, tactile size, emphasis & individual character */
.backtop{isolation:isolate;-webkit-tap-highlight-color:transparent;}
.backtop:focus-visible{outline:3px solid #f0af42;outline-offset:4px;}
@media(prefers-reduced-motion:reduce){.backtop,.backtop *{transition-duration:.01ms!important;animation-duration:.01ms!important}}

.w2051{right:clamp(20px,3.8vw,54px);bottom:clamp(28px,5vh,64px);width:70px;height:70px;border:3px solid #fbefe6;box-shadow:0 0 0 1px #bc4b31,0 12px 24px #5a2e2440;}
.w2051:hover{transform:translateY(-5px) rotate(-6deg);box-shadow:0 0 0 1px #bc4b31,0 16px 30px #5a2e2455;}
@media(max-width:650px){.w2051{right:19px;bottom:24px;width:64px;height:64px}}

(()=>{'use strict';const button=document.querySelector('.backtop');if(!button)return;const footerOnly=button.classList.contains('footer-backtop');const reduced=matchMedia('(prefers-reduced-motion: reduce)');let scheduled=false;function update(){scheduled=false;if(footerOnly)return;const shown=window.scrollY>160;button.classList.toggle('is-visible',shown);button.classList.toggle('is-hidden',!shown);button.tabIndex=shown?0:-1;button.setAttribute('aria-hidden',String(!shown));if(button.classList.contains('w2056')){const max=Math.max(1,document.documentElement.scrollHeight-innerHeight);button.style.setProperty('--progress',(Math.round(Math.min(100,scrollY/max*100)))+'%');}}function onScroll(){if(!scheduled){scheduled=true;requestAnimationFrame(update)}}button.addEventListener('click',()=>window.scrollTo({top:0,behavior:reduced.matches?'instant':'smooth'}));addEventListener('scroll',onScroll,{passive:true});addEventListener('resize',onScroll,{passive:true});update();})();

How to Use

Insert the HTML button near the end of body, load the CSS, and include JavaScript using defer. Test scrolling, returning to the top, and positioning on mobile.

Use Case

Galleries, visual portfolios and curated creative projects.

Technical Notes

Keep controls usable on touch devices. Test keyboard focus and reduced-motion preferences.

Mobile：Check tap target and placement on mobile devices.

Browser：Test in your supported browsers.

Reduced Motion：CSS respects prefers-reduced-motion.