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Source: HTML Rendering

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CSS Performance

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CSS Performance

How does CSS work?

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How does CSS work?

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How does CSS work?

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CSS Performance

How does CSS work?

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@media

<link rel="stylesheet" href="all.css" media="all" />
<link rel="stylesheet" href="small.css" media="(min-width: 20em)" />
<link rel="stylesheet" href="medium.css" media="(min-width: 64em)" />
<link rel="stylesheet" href="large.css" media="(min-width: 90em)" />
<link rel="stylesheet" href="extra-large.css" media="(min-width: 120em)" />
<link rel="stylesheet" href="print.css" media="print" />

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1,3 MB

CSS Conf Web Site

CSS Optimization

Tips

350 KB

CSS Conf Web Site

CSS Optimization

Tips

Original

Grey + CSS

.mate {
  background-color: #ab3a3c;
}
.mate-image {
  ...
  mix-blend-mode: hard-light;
}

CSS Conf Web Site

CSS Optimization

Tips

CSS Conf Web Site

CSS Optimization

Tips

/* cyrillic-ext */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmYmRlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+0460-052F, U+1C80-1C88, U+20B4, U+2DE0-2DFF, U+A640-A69F, U+FE2E-FE2F;
}
/* cyrillic */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISma2RlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
/* greek-ext */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmY2RlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+1F00-1FFF;
}
/* greek */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmbGRlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+0370-03FF;
}
/* vietnamese */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmYGRlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+0102-0103, U+0110-0111, U+0128-0129, U+0168-0169, U+01A0-01A1, U+01AF-01B0, U+1EA0-1EF9, U+20AB;
}
/* latin-ext */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmYWRlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}
/* latin */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmb2RlV9Su1cai.woff) format('woff');
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

https://fonts.googleapis.com/css?family=Roboto+Slab&display=swap

CSS Conf Web Site

CSS Optimization

Tips

/* latin-ext */
@font-face {
  font-family: 'Roboto Slab';
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url(https://fonts.gstatic.com/s/robotoslab/v13/BngbUXZYTXPIvIBgJJSb6s3BzlRRfKOFbvjojISmYWRlV9Su1caiTVo.woff) format('woff');
  unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
}

https://fonts.googleapis.com/css?family=Roboto+Slab&display=swap

Resources

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Load only the CSS that you page needs

Use CSS Optimization Tools

Self host all resources as possible

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