body{background:#f8f9fa;font:sans-serif;display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;margin:0;color:#37474f;transition:background .3s,color .3s}
a{color:inherit;text-decoration:none}
a:hover{text-decoration:underline}
.d{background:#121212;color:#fff}
.c{background:#fff;padding:32px;border-radius:8px;box-shadow:0 2px 4px rgba(0,0,0,.1);text-align:center;transition:background .3s}
.d .c{background:#333}
#img{animation:r 5s linear infinite;margin-bottom:16px;color:#4285f4;font-size:48px;cursor:pointer}
@keyframes r{to{transform:rotate(360deg)}}
.d #img{filter:invert(1)}
.tr{position:absolute;top:16px;right:16px}
.btn{background:#eee;border:1px solid #ccc;border-radius:4px;padding:8px 12px;cursor:pointer;font-size:14px;transition:background .3s}
.d .btn{background:#555;color:#fff;border-color:#777}
.footer{margin-top:16px;font-size:14px;color:#ffa000}