Soft Current — Morphing Return

Source Code

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

<!-- TB-2070 / Soft Current / 変形する水滴 | paste before the closing body tag (inside the footer for TB-2069) -->
<button aria-label="ページの先頭へ戻る" class="btt blob tb-btt-2070" type="button"><span class="blob-water">◌</span><span class="blob-label">return</span></button>

/* 2070 / production button rules only */
.tb-btt-2070{box-sizing:border-box;font:inherit;cursor:pointer}.tb-btt-2070 :is(span,i,em,b,small,img){box-sizing:border-box}
.btt.tb-btt-2070{position:fixed;z-index:90;border:0;cursor:pointer;-webkit-tap-highlight-color:transparent;opacity:0;visibility:hidden;pointer-events:none;transition:opacity .28s ease,visibility .28s ease,transform .35s ease}.btt.tb-btt-2070:focus-visible{outline:3px solid #f0af43;outline-offset:5px}.tb-btt-2070 .blob{right:22px;bottom:24px;width:88px;height:87px;border-radius:56% 44% 31% 69% / 44% 32% 68% 56%;background:linear-gradient(140deg,#8dc9b5,#a7bde4 70%,#e8c1d9);box-shadow:0 13px 24px #2b7d6b35;color:#143e3b;display:grid;place-items:center;animation:tb-btt-2070-flowBlob 7s ease-in-out infinite;transition:width .5s,height .5s,opacity .28s,visibility .28s,background .5s}.tb-btt-2070 .blob-water{position:absolute;top:2px;left:26px;font:400 49px/1 Georgia,serif;opacity:.5}.tb-btt-2070 .blob-label{font:italic 600 15px/1 Georgia,serif;letter-spacing:.02em}.tb-btt-2070 .blob:hover{width:142px;height:72px;border-radius:999px;background:linear-gradient(100deg,#95dbbf,#c9c4f1);animation:none}@media  (max-width:600px){.tb-btt-2070 .blob{right:14px;bottom:18px;width:72px;height:72px}.tb-btt-2070 .blob:hover{width:115px;height:62px}.tb-btt-2070 .blob-water{left:18px}}
@keyframes tb-btt-2070-heroMorph{50%{border-radius:35% 65% 45% 55%;transform:translateY(25px) rotate(10deg)}}
@keyframes tb-btt-2070-flowBlob{0%,100%{border-radius:56% 44% 31% 69% / 44% 32% 68% 56%;transform:translateY(0)}50%{border-radius:32% 68% 55% 45% / 62% 50% 50% 38%;transform:translateY(-9px)}}
@media(prefers-reduced-motion:reduce){.tb-btt-2070,.tb-btt-2070 *{animation-duration:.01ms!important;transition-duration:.01ms!important}}

(()=>{'use strict';const target=document.querySelector('.btt, .footer-return');if(!target)return;const isFooter=target.classList.contains('footer-return');const reduced=matchMedia('(prefers-reduced-motion: reduce)');let active=false;const update=()=>{const y=window.scrollY;const p=Math.max(0,Math.min(1,y/Math.max(1,document.documentElement.scrollHeight-innerHeight)));if(!isFooter){const visible=y>160;target.classList.toggle('is-visible',visible);target.setAttribute('aria-hidden',String(!visible));target.tabIndex=visible?0:-1;}target.style.setProperty('--pct',p.toFixed(3));const txt=target.querySelector('[data-progress]');if(txt)txt.textContent=String(Math.round(100*p)).padStart(2,'0')+'%';};const scroll=()=>{if(active)return;active=true;requestAnimationFrame(()=>{active=false;update()})};target.addEventListener('click',()=>window.scrollTo({top:0,behavior:reduced.matches?'instant':'smooth'}));addEventListener('scroll',scroll,{passive:true});addEventListener('resize',scroll,{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

Wellness and natural skincare websites.

Technical Notes

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

Mobile：Check tap target, visibility and positioning on small screens.

Browser：Designed for current Chrome, Edge, Firefox and Safari.

Reduced Motion：CSS animations respect the reduced-motion preference.