You can do this using SVG as background:
.bottom-bar {
background: #29a7e8;
position: absolute;
bottom: 0;
width: 100%;
height: 50px;
text-align: center;
}
.circle {
display: inline-block;
position: relative;
top: -28px;
border-radius: 100%;
background: url("data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox='10 10 45 15' width="64" height="64" fill="%2329a7e8"><path d='M12 24 L52 24 L52 16 C40 16 42 10 32 10 C20 10 22 16 12 16 Z' /></svg>") 0 0/100% 100% no-repeat;
width: 60px;
height: 60px;
margin: 0 1rem;
}
<div class="bottom-bar">
<div class="circle"></div>
<div class="circle"></div>
<div class="circle"></div>
</div>
<svg xmlns="http://www.w3.org/2000/svg"
viewBox='10 10 45 15'
width="64" height="64"
fill="#29a7e8">
<path d='M12 24 L52 24 L52 16 C40 16 42 10 32 10 C20 10 22 16 12 16 Z' />
</svg>
For a CSS only solution you can consider a combination of radial-gradient to create the curve:
.bottom-bar {
background: #29a7e8;
position: absolute;
bottom: 0;
width: 100%;
height: 50px;
text-align: center;
}
.circle {
display: inline-block;
position: relative;
top: -30px;
background:
radial-gradient(circle at top right,transparent 50%,#29a7e8 51%)100% 21px/12px 10px no-repeat,
radial-gradient(circle at top left,transparent 50%,#29a7e8 51%)0 21px/12px 10px no-repeat,
radial-gradient(circle at center,#29a7e8 55%, transparent 56%);
width: 60px;
height: 60px;
margin: 0 1rem;
}
<div class="bottom-bar">
<div class="circle"></div>
<div class="circle"></div>
<div class="circle"></div>
</div>