二重カギ括弧をつけたCSS見出しデザイン

before、after疑似要素で「border」プロパティを指定し「border-style」を「double」にして括弧を作っています

<html style="max-height: 100%;"><head><script id="js-section"> </script><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><style id="basic-style">body,#svg-section{font-family:-apple-system,BlinkMacSystemFont,'Helvetica Neue','游ゴシック Medium',YuGothic,YuGothicM,'Hiragino Kaku Gothic ProN',メイリオ,Meiryo,sans-serif;}a,abbr,acronym,address,applet,article,aside,audio,b,big,blockquote,body,canvas,caption,center,cite,code,dd,del,details,dfn,div,dl,dt,em,embed,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,html,i,iframe,img,ins,kbd,label,legend,li,mark,menu,nav,object,ol,output,p,pre,q,ruby,s,samp,section,small,span,strike,strong,sub,summary,sup,table,tbody,td,tfoot,th,thead,time,tr,tt,u,ul,var,video{margin:0;padding:0;border:0;font-size:100%;font:inherit;vertical-align:baseline}article,aside,details,figcaption,figure,footer,header,hgroup,menu,nav,section{display:block}body,svg{line-height:1}ol,ul{list-style:none}blockquote,q{quotes:none}blockquote:after,blockquote:before,q:after,q:before{content:'';content:none}table{border-collapse:collapse;border-spacing:0}</style><style id="root-style">:root{--pic-image-data:none;}</style><style id="out-style">.pic-container { display: flex; justify-content: center; flex-direction: column; width: 600px; height: 338px; padding: 0 6rem; box-sizing: border-box; background-color: #fefefe; } h2 { position: relative; padding: 1rem; font-size: 24px; font-weight: bold; text-align: center; } h2::before, h2::after { position: absolute; width: 20px; height: 30px; content: ''; } h2::before { border-left: double 5px; border-top: double 5px; top: 0; left: 0; } h2::after { border-right: double 5px; border-bottom: double 5px; bottom: 0; right: 0; } </style><style id="pic-style"></style><style id="body-style">body,#svg-section {font-family:-apple-system,BlinkMacSystemFont,'Helvetica Neue','游ゴシック Medium',YuGothic,YuGothicM,'Hiragino Kaku Gothic ProN',メイリオ,Meiryo,sans-serif;}</style><link href="chrome-extension://nffaoalbilbmmfgbnbgppjihopabppdk/inject.css" type="text/css" rel="stylesheet"></head><body id="svg-section" style="width: 600px; height: 337.5px; transform-origin: left top; transform: scale(1); overflow: auto;" class="vsc-initialized"><div class="pic-container pic-background"> <h2>CSSでつくる見出しデザイン</h2> </div> </body></html>

カギ括弧を付けたCSS見出しデザイン

before、after疑似要素で「border」プロパティを指定し括弧を作っています

<html style="max-height: 100%;"><head><script id="js-section"> </script><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><style id="basic-style">body,#svg-section{font-family:-apple-system,BlinkMacSystemFont,'Helvetica Neue','游ゴシック Medium',YuGothic,YuGothicM,'Hiragino Kaku Gothic ProN',メイリオ,Meiryo,sans-serif;}a,abbr,acronym,address,applet,article,aside,audio,b,big,blockquote,body,canvas,caption,center,cite,code,dd,del,details,dfn,div,dl,dt,em,embed,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,html,i,iframe,img,ins,kbd,label,legend,li,mark,menu,nav,object,ol,output,p,pre,q,ruby,s,samp,section,small,span,strike,strong,sub,summary,sup,table,tbody,td,tfoot,th,thead,time,tr,tt,u,ul,var,video{margin:0;padding:0;border:0;font-size:100%;font:inherit;vertical-align:baseline}article,aside,details,figcaption,figure,footer,header,hgroup,menu,nav,section{display:block}body,svg{line-height:1}ol,ul{list-style:none}blockquote,q{quotes:none}blockquote:after,blockquote:before,q:after,q:before{content:'';content:none}table{border-collapse:collapse;border-spacing:0}</style><style id="root-style">:root{--pic-image-data:none;}</style><style id="out-style">.pic-container { display: flex; justify-content: center; flex-direction: column; width: 600px; height: 338px; padding: 0 6rem; box-sizing: border-box; background-color: #fefefe; } h2 { position: relative; padding: 1rem; font-size: 24px; font-weight: bold; text-align: center; } h2::before, h2::after { position: absolute; width: 30px; height: 30px; content: ''; } h2::before { border-left: solid 3px; border-top: solid 3px; top: 0; left: 0; } h2::after { border-right: solid 3px; border-bottom: solid 3px; bottom: 0; right: 0; } </style><style id="pic-style"></style><style id="body-style">body,#svg-section {font-family:-apple-system,BlinkMacSystemFont,'Helvetica Neue','游ゴシック Medium',YuGothic,YuGothicM,'Hiragino Kaku Gothic ProN',メイリオ,Meiryo,sans-serif;}</style><link href="chrome-extension://nffaoalbilbmmfgbnbgppjihopabppdk/inject.css" type="text/css" rel="stylesheet"></head><body id="svg-section" style="width: 600px; height: 337.5px; transform-origin: left top; transform: scale(1); overflow: auto;" class="vsc-initialized"><div class="pic-container pic-background"> <h2>CSSでつくる見出しデザイン</h2> </div> </body></html>