Moon Phase Return

Source Code

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

<button aria-label="ページの先頭へ戻る" class="back-top back-top-2101 tb-btt-button" title="ページの先頭へ戻る" type="button"><span aria-hidden="true" class="moon-orbit"><i>◕</i><i>◐</i><i>◑</i></span><span aria-hidden="true" class="btt-symbol">↑</span><span class="btt-main">天頂へ</span><span class="btt-meta">TOP</span></button>

/* TIPSBLOCKS Back to Top — standalone control only. */
.tb-btt-button,.tb-btt-button *,.tb-btt-button *::before,.tb-btt-button *::after{box-sizing:border-box}
.tb-btt-button{font-family:"Noto Sans JP","Hiragino Kaku Gothic ProN","Yu Gothic",system-ui,sans-serif;--accent:#26393b}
.tb-btt-button:focus-visible{outline:3px solid #edb45f;outline-offset:4px}
@media(prefers-reduced-motion:reduce){.tb-btt-button,.tb-btt-button *{animation-duration:.01ms!important;transition-duration:.01ms!important}}
.back-top{font-family:inherit;appearance:none;border:0;cursor:pointer;display:flex;align-items:center;justify-content:center;flex-direction:column;position:fixed;z-index:30;opacity:0;visibility:hidden;pointer-events:none;transform:translateY(14px);transition:opacity .28s,transform .28s,visibility .28s;isolation:isolate}
.back-top.is-visible{opacity:1;visibility:visible;pointer-events:auto;transform:translateY(0)}
.back-top.is-returning{pointer-events:none}
.back-top .btt-symbol{font-weight:450;font-size:27px;line-height:1}
.back-top .btt-main{font-weight:750;line-height:1.45;text-align:center;letter-spacing:.06em}
.back-top .btt-meta{font-size:9px;line-height:1.4;letter-spacing:.11em;text-align:center}
.back-top:hover{filter:brightness(1.1)}
@media (max-width:650px){.back-top{max-width:112px}}
@keyframes flame{to{transform:scaleY(1.45);background:#ffc34a}}
.back-top-2101{right:23px;top:47%;width:116px;height:116px;border:2px solid #c9bb91;border-radius:50%;background:radial-gradient(circle at 40% 30%,#3d5370,#101b30 64%);color:#fff6d4;box-shadow:0 0 0 5px #0d1627dd,0 6px 20px #0009}
.back-top-2101 .moon-orbit{position:absolute;inset:4px;display:flex;justify-content:space-around;align-items:flex-start}
.back-top-2101 .moon-orbit i{font-style:normal;font-size:13px;color:#e9d2a0}
.back-top-2101 .btt-main{margin-top:5px;font-size:14px}
.back-top-2101 .btt-meta{margin-top:2px}
.back-top-2101:hover{box-shadow:0 0 0 5px #0d1627dd,0 0 35px #c8ac6699}
@keyframes buoybob{to{translate:0 -5px}}
@media (max-width:650px){.back-top-2101{width:83px;height:83px;right:9px;top:auto;bottom:15px}
.back-top-2101 .moon-orbit i{font-size:9px}
.back-top-2101 .btt-main{font-size:12px}
.back-top-2101 .btt-symbol{font-size:20px}}

/** TIPSBLOCKS TB-2101 — independent Back to Top. */
(()=>{'use strict';
 const control=document.querySelector('.tb-btt-button.back-top-2101');if(!control)return;
 const footer=false;
 const reduced=window.matchMedia('(prefers-reduced-motion: reduce)');
 const threshold=190;
 let raf=0;
 function update(){raf=0;const visible=footer||window.scrollY>threshold;
 control.classList.toggle('is-visible',visible);
 if(!footer){control.setAttribute('aria-hidden',String(!visible));control.tabIndex=visible?0:-1;}
 }
 window.addEventListener('scroll',()=>{if(!raf)raf=requestAnimationFrame(update)},{passive:true});
 window.addEventListener('resize',update,{passive:true});
 control.addEventListener('click',()=>{control.classList.add('is-returning');
 window.scrollTo({top:0,behavior:reduced.matches?'instant':'smooth'});
 if(reduced.matches)control.classList.remove('is-returning');
 else {const onStop=()=>{if(window.scrollY<=3){control.classList.remove('is-returning');window.removeEventListener('scroll',onStop)}};
 window.addEventListener('scroll',onStop,{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

Observatories and planetarium 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.