CSS Reference

font-optical-sizing

オプティカルサイズを許可するか指定する

font-optical-sizing プロパティは、オプティカルサイズを許可（フォントサイズに応じた最適化を実行）するかどうかを指定します。

オプティカルサイズに対応したフォントは、使用用途（表示される文字のサイズ）に応じて、文字のデザイン（線の太さなど）が調整されています。例えば、キャプションなどで使用され、小さな文字サイズで表示された場合でも読みやすくするために、文字サイズが小さいときは少し太め、かつ幅を少し大きくするように調整されていたり、見出しなど、大きなサイズの場合は、太いストロークと細いストロークの対比がより強調されるといった調整が一般的に行われます。

font-optical-sizing プロパティは、このオプティカルサイズを有効にするか、しないかを指定することができます。

指定できる値は下記の通りです。

`auto`	オプティカルサイズを許可する。（既定値）
`none`	オプティカルサイズを許可しない。

font-optical-sizingの仕様

初期値: auto

対象となる要素: すべての要素
継承: あり

font-optical-sizingのサンプルソース

font-optical-sizing: none;
font-optical-sizing: auto;

主要ブラウザの対応

IE11	×
Edge（EdgeHTML）	×
Edge（Chromium）	○
Chrome	○
Firefox	○
Safari	○
iOS Safari	○
Android Chrome	○

仕様書

8.1. Optical sizing control: the font-optical-sizing property - CSS Fonts Module Level 4

用途から CSS プロパティやセレクタを探す

用途から CSS プロパティやセレクタを逆引きできます。

@-規則: @charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scope
@scroll-timeline
@starting-style
@supports
メディアクエリ: prefers-color-scheme
コンテナクエリ: container
container-name
container-type
セレクタ: ID セレクタ
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
疑似要素: ::after
::backdrop
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
疑似クラス: :active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:fullscreen
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:is()
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:right
:root
:scope
:state()
:target
:valid
:visited
:where()
CSS関数: acos()
asin()
atan()
atan2()
attr()
brightness()
calc()
calc-size()
circle()
clamp()
color()
color-mix()
cos()
counters()
device-cmyk()
drop-shadow()
ellipse()
env()
exp()
grayscale()
hue-rotate()
hypot()
inset()
invert()
light-dark()
log()
max()
min()
minmax()
mod()
polygon()
pow()
rem()
round()
saturate()
sepia()
sin()
sqrt()
tan()
フォント・テキスト: font-optical-sizing
font-palette
font-synthesis
font-synthesis-position
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
hyphenate-character
hyphens
text-spacing-trim
text-underline-offset
text-wrap
text-wrap-mode
text-wrap-style
white-space-collapse
色の指定: accent-color
background-color
color-scheme
light-dark()
背景: background
background-color
ボックス: aspect-ratio
block-size
inline-size
object-fit
object-position
scroll-behavior
配置: anchor()
anchor-name
anchor-size()
inset
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
position-anchor
position-area
ルビ: ruby-align
ruby-position
グラデーション: conic-gradient()
linear-gradient()
radial-gradient()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
アニメーション: @keyframes
@scroll-timeline
animation-timeline
interpolate-size
scroll-timeline
scroll-timeline-axis
scroll-timeline-name
transition-behavior
トランスフォーム: rotate
scale
translate
ユーザーインターフェース: appearance
field-sizing
封じ込め: contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
content-visibility
コンテンツ: quotes
カウンター: counter-set
counters()
スクロールバー: scrollbar-color
scrollbar-gutter
scrollbar-width
SVG: clip-rule
その他: user-select

対応ブラウザから CSS プロパティやセレクタを探す

対応ブラウザから CSS プロパティやセレクタを逆引きできます。

IE11: ::after
::backdrop
::before
::first-letter
::first-line
::selection
:active
:checked
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:fullscreen
:hover
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:placeholder-shown
:required
:right
:root
:target
:valid
:visited
@charset
@keyframes
@namespace
@page
ID セレクタ
attr()
background
background-color
calc()
hyphens
linear-gradient()
radial-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
user-select
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
Edge（EdgeHTML）: ::after
::backdrop
::before
::first-letter
::first-line
::placeholder
::selection
:active
:checked
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:fullscreen
:hover
:in-range
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:read-only
:read-write
:required
:right
:root
:target
:valid
:visited
@charset
@keyframes
@namespace
@page
@supports
ID セレクタ
attr()
background
background-color
brightness()
calc()
counters()
drop-shadow()
grayscale()
hue-rotate()
hyphens
invert()
linear-gradient()
minmax()
prefers-color-scheme
quotes
radial-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
saturate()
sepia()
transition-behavior
user-select
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
Edge（Chromium）: ::after
::backdrop
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
:active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:fullscreen
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:right
:root
:scope
:state()
:target
:valid
:visited
@charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scope
@starting-style
@supports
ID セレクタ
accent-color
acos()
anchor()
anchor-name
anchor-size()
animation-timeline
appearance
asin()
aspect-ratio
atan()
atan2()
attr()
background
background-color
block-size
brightness()
calc()
calc-size()
circle()
clamp()
clip-rule
color()
color-mix()
color-scheme
conic-gradient()
contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
container
container-name
container-type
content-visibility
cos()
counter-set
counters()
drop-shadow()
ellipse()
env()
exp()
field-sizing
font-optical-sizing
font-palette
font-synthesis
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
grayscale()
hue-rotate()
hyphenate-character
hyphens
hypot()
inline-size
inset
inset()
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
interpolate-size
invert()
light-dark()
linear-gradient()
log()
max()
min()
minmax()
mod()
object-fit
object-position
polygon()
position-anchor
position-area
pow()
prefers-color-scheme
quotes
radial-gradient()
rem()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
rotate
round()
ruby-align
ruby-position
saturate()
scale
scroll-behavior
scroll-timeline
scroll-timeline-axis
scroll-timeline-name
scrollbar-color
scrollbar-gutter
scrollbar-width
sepia()
sin()
sqrt()
tan()
text-spacing-trim
text-underline-offset
text-wrap
transition-behavior
translate
user-select
white-space-collapse
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
Firefox: ::after
::backdrop
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
:active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:fullscreen
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:is()
:lang()
:last-child
:last-of-type
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:root
:scope
:state()
:target
:valid
:visited
:where()
@charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scroll-timeline
@starting-style
@supports
ID セレクタ
accent-color
acos()
appearance
asin()
aspect-ratio
atan()
atan2()
attr()
background
background-color
block-size
brightness()
calc()
circle()
clamp()
clip-rule
color()
color-mix()
color-scheme
conic-gradient()
contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
container
container-name
container-type
content-visibility
cos()
counter-set
counters()
drop-shadow()
ellipse()
env()
exp()
font-optical-sizing
font-palette
font-synthesis
font-synthesis-position
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
grayscale()
hue-rotate()
hyphenate-character
hyphens
hypot()
inline-size
inset
inset()
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
invert()
light-dark()
linear-gradient()
log()
max()
min()
minmax()
mod()
object-fit
object-position
polygon()
pow()
prefers-color-scheme
quotes
radial-gradient()
rem()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
rotate
round()
ruby-align
ruby-position
saturate()
scale
scroll-behavior
scrollbar-color
scrollbar-gutter
scrollbar-width
sepia()
sin()
sqrt()
tan()
text-underline-offset
text-wrap
text-wrap-mode
text-wrap-style
transition-behavior
translate
user-select
white-space-collapse
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
Chrome: ::after
::backdrop
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
:active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:fullscreen
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:right
:root
:scope
:state()
:target
:valid
:visited
@charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scope
@starting-style
@supports
ID セレクタ
accent-color
acos()
anchor()
anchor-name
anchor-size()
animation-timeline
appearance
asin()
aspect-ratio
atan()
atan2()
attr()
background
background-color
block-size
brightness()
calc()
calc-size()
circle()
clamp()
clip-rule
color()
color-mix()
color-scheme
conic-gradient()
contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
container
container-name
container-type
content-visibility
cos()
counter-set
counters()
drop-shadow()
ellipse()
env()
exp()
field-sizing
font-optical-sizing
font-palette
font-synthesis
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
grayscale()
hue-rotate()
hyphenate-character
hyphens
hypot()
inline-size
inset
inset()
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
interpolate-size
invert()
light-dark()
linear-gradient()
log()
max()
min()
minmax()
mod()
object-fit
object-position
polygon()
position-anchor
position-area
pow()
prefers-color-scheme
quotes
radial-gradient()
rem()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
rotate
round()
ruby-align
ruby-position
saturate()
scale
scroll-behavior
scroll-timeline
scroll-timeline-axis
scroll-timeline-name
scrollbar-color
scrollbar-gutter
scrollbar-width
sepia()
sin()
sqrt()
tan()
text-spacing-trim
text-underline-offset
text-wrap
transition-behavior
translate
user-select
white-space-collapse
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
Safari: ::after
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
:active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:right
:root
:scope
:state()
:target
:valid
:visited
@charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scope
@starting-style
@supports
ID セレクタ
accent-color
acos()
appearance
asin()
aspect-ratio
atan()
atan2()
attr()
background
background-color
block-size
brightness()
calc()
circle()
clip-rule
color()
color-mix()
color-scheme
conic-gradient()
contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
container
container-name
container-type
content-visibility
cos()
counter-set
counters()
drop-shadow()
ellipse()
env()
exp()
font-optical-sizing
font-palette
font-synthesis
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
grayscale()
hue-rotate()
hyphenate-character
hyphens
hypot()
inline-size
inset
inset()
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
invert()
light-dark()
linear-gradient()
log()
max()
min()
minmax()
mod()
object-fit
object-position
polygon()
pow()
prefers-color-scheme
quotes
radial-gradient()
rem()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
rotate
round()
ruby-position
saturate()
scale
scroll-behavior
sepia()
sin()
sqrt()
tan()
text-underline-offset
text-wrap
text-wrap-mode
text-wrap-style
transition-behavior
translate
user-select
white-space-collapse
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
iOS Safari: ::after
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
:active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:fullscreen
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:right
:root
:scope
:state()
:target
:valid
:visited
@charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scope
@starting-style
@supports
ID セレクタ
accent-color
acos()
appearance
asin()
aspect-ratio
atan()
atan2()
attr()
background
background-color
block-size
brightness()
calc()
circle()
clip-rule
color()
color-mix()
color-scheme
conic-gradient()
contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
container
container-name
container-type
content-visibility
cos()
counter-set
counters()
drop-shadow()
ellipse()
env()
exp()
font-optical-sizing
font-palette
font-synthesis
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
grayscale()
hue-rotate()
hyphenate-character
hyphens
hypot()
inline-size
inset
inset()
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
invert()
light-dark()
linear-gradient()
log()
max()
min()
minmax()
mod()
object-fit
object-position
polygon()
pow()
prefers-color-scheme
quotes
radial-gradient()
rem()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
rotate
round()
ruby-position
saturate()
scale
scroll-behavior
sepia()
sin()
sqrt()
tan()
text-underline-offset
text-wrap
text-wrap-mode
text-wrap-style
transition-behavior
translate
user-select
white-space-collapse
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ
Android Chrome: ::after
::backdrop
::before
::cue
::file-selector-button
::first-letter
::first-line
::marker
::part()
::placeholder
::selection
::slotted()
:active
:any-link
:checked
:default
:defined
:disabled
:empty
:enabled
:first
:first-child
:first-of-type
:focus
:focus-visible
:focus-within
:fullscreen
:has()
:host
:hover
:in-range
:indeterminate
:invalid
:lang()
:last-child
:last-of-type
:left
:link
:not()
:nth-child()
:nth-last-child()
:nth-last-of-type()
:nth-of-type()
:only-child
:only-of-type
:optional
:out-of-range
:placeholder-shown
:read-only
:read-write
:required
:right
:root
:scope
:state()
:target
:visited
@charset
@color-profile
@container
@counter-style
@font-feature-values
@font-palette-values
@keyframes
@layer
@namespace
@page
@property
@scope
@starting-style
@supports
ID セレクタ
accent-color
acos()
anchor()
anchor-name
anchor-size()
animation-timeline
appearance
asin()
aspect-ratio
atan()
atan2()
attr()
background
background-color
block-size
brightness()
calc()
calc-size()
circle()
clamp()
clip-rule
color()
color-mix()
color-scheme
conic-gradient()
contain
contain-intrinsic-block-size
contain-intrinsic-height
contain-intrinsic-inline-size
contain-intrinsic-size
contain-intrinsic-width
container
container-name
container-type
content-visibility
cos()
counter-set
counters()
drop-shadow()
ellipse()
env()
exp()
field-sizing
font-optical-sizing
font-palette
font-synthesis
font-synthesis-small-caps
font-synthesis-style
font-synthesis-weight
font-variant-position
font-variation-settings
grayscale()
hue-rotate()
hyphenate-character
hyphens
hypot()
inline-size
inset
inset()
inset-block
inset-block-end
inset-block-start
inset-inline
inset-inline-end
inset-inline-start
interpolate-size
invert()
light-dark()
linear-gradient()
log()
max()
min()
minmax()
mod()
object-fit
object-position
polygon()
position-anchor
position-area
pow()
prefers-color-scheme
quotes
radial-gradient()
rem()
repeating-conic-gradient()
repeating-linear-gradient()
repeating-radial-gradient()
rotate
round()
ruby-align
ruby-position
saturate()
scale
scroll-behavior
scroll-timeline
scroll-timeline-axis
scroll-timeline-name
scrollbar-color
scrollbar-gutter
scrollbar-width
sepia()
sin()
sqrt()
tan()
text-spacing-trim
text-underline-offset
text-wrap
transition-behavior
translate
user-select
white-space-collapse
クラスセレクタ
タイプセレクタ
ユニバーサルセレクタ
入れ子セレクタ
子セレクタ
子孫セレクタ
属性セレクタ
間接セレクタ
隣接セレクタ