none {border:none #9900CC 5px};

hidden

solid

double

groove

ridge

inset

outset

dashed

dotted

https://seolaboratory.jp/66605/

.text_kasen {
	background:linear-gradient(transparent 70%, #FFFF00 0%);
}

文字数に応じて下線を引く

h1 {
	border-bottom: 3px solid gray;
	display: inline-block;
}