WordPress editor custom styles

Question

Using the following code I'm trying to add some CSS to the default Gutenberg editor in Wordpress:

function editor_style() {
    add_theme_support( 'editor-styles' );
    add_editor_style( 'editor-style.css' );
}
add_action( 'after_setup_theme', 'editor_style' );

While this works, it also makes the editor look weird:

It seems as if all styles are removed other than those from my custom stylesheet. Is this intentional? I'm using Bootstrap in my theme. Should I include this here too?

Answer 1

I've found the issue. In the block editor WordPress includes some 'on page' <style> tags.

These inline style tags are removed when using your own editor style. You can fix this by adding the inline styles directly on top of your custom editor style file (place this on top of your editor-style.css):

:root{--wp-admin-theme-color:#007cba;--wp-admin-theme-color--rgb:0,124,186;--wp-admin-theme-color-darker-10:#006ba1;--wp-admin-theme-color-darker-10--rgb:0,107,161;--wp-admin-theme-color-darker-20:#005a87;--wp-admin-theme-color-darker-20--rgb:0,90,135;--wp-admin-border-width-focus:2px;--wp-block-synced-color:#7a00df;--wp-block-synced-color--rgb:122,0,223;--wp-bound-block-color:var(--wp-block-synced-color);--wp--preset--aspect-ratio--square:1;--wp--preset--aspect-ratio--4-3:4/3;--wp--preset--aspect-ratio--3-4:3/4;--wp--preset--aspect-ratio--3-2:3/2;--wp--preset--aspect-ratio--2-3:2/3;--wp--preset--aspect-ratio--16-9:16/9;--wp--preset--aspect-ratio--9-16:9/16;--wp--preset--color--black:#000000;--wp--preset--color--cyan-bluish-gray:#abb8c3;--wp--preset--color--white:#ffffff;--wp--preset--color--pale-pink:#f78da7;--wp--preset--color--vivid-red:#cf2e2e;--wp--preset--color--luminous-vivid-orange:#ff6900;--wp--preset--color--luminous-vivid-amber:#fcb900;--wp--preset--color--light-green-cyan:#7bdcb5;--wp--preset--color--vivid-green-cyan:#00d084;--wp--preset--color--pale-cyan-blue:#8ed1fc;--wp--preset--color--vivid-cyan-blue:#0693e3;--wp--preset--color--vivid-purple:#9b51e0;--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple:linear-gradient(135deg, rgba(6, 147, 227, 1) 0%, rgb(155, 81, 224) 100%);--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan:linear-gradient(135deg, rgb(122, 220, 180) 0%, rgb(0, 208, 130) 100%);--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange:linear-gradient(135deg, rgba(252, 185, 0, 1) 0%, rgba(255, 105, 0, 1) 100%);--wp--preset--gradient--luminous-vivid-orange-to-vivid-red:linear-gradient(135deg, rgba(255, 105, 0, 1) 0%, rgb(207, 46, 46) 100%);--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray:linear-gradient(135deg, rgb(238, 238, 238) 0%, rgb(169, 184, 195) 100%);--wp--preset--gradient--cool-to-warm-spectrum:linear-gradient(135deg, rgb(74, 234, 220) 0%, rgb(151, 120, 209) 20%, rgb(207, 42, 186) 40%, rgb(238, 44, 130) 60%, rgb(251, 105, 98) 80%, rgb(254, 248, 76) 100%);--wp--preset--gradient--blush-light-purple:linear-gradient(135deg, rgb(255, 206, 236) 0%, rgb(152, 150, 240) 100%);--wp--preset--gradient--blush-bordeaux:linear-gradient(135deg, rgb(254, 205, 165) 0%, rgb(254, 45, 45) 50%, rgb(107, 0, 62) 100%);--wp--preset--gradient--luminous-dusk:linear-gradient(135deg, rgb(255, 203, 112) 0%, rgb(199, 81, 192) 50%, rgb(65, 88, 208) 100%);--wp--preset--gradient--pale-ocean:linear-gradient(135deg, rgb(255, 245, 203) 0%, rgb(182, 227, 212) 50%, rgb(51, 167, 181) 100%);--wp--preset--gradient--electric-grass:linear-gradient(135deg, rgb(202, 248, 128) 0%, rgb(113, 206, 126) 100%);--wp--preset--gradient--midnight:linear-gradient(135deg, rgb(2, 3, 129) 0%, rgb(40, 116, 252) 100%);--wp--preset--font-size--small:13px;--wp--preset--font-size--medium:20px;--wp--preset--font-size--large:36px;--wp--preset--font-size--x-large:42px;--wp--preset--spacing--20:0.44rem;--wp--preset--spacing--30:0.67rem;--wp--preset--spacing--40:1rem;--wp--preset--spacing--50:1.5rem;--wp--preset--spacing--60:2.25rem;--wp--preset--spacing--70:3.38rem;--wp--preset--spacing--80:5.06rem;--wp--preset--shadow--natural:6px 6px 9px rgba(0, 0, 0, 0.2);--wp--preset--shadow--deep:12px 12px 50px rgba(0, 0, 0, 0.4);--wp--preset--shadow--sharp:6px 6px 0px rgba(0, 0, 0, 0.2);--wp--preset--shadow--outlined:6px 6px 0px -3px rgba(255, 255, 255, 1),6px 6px rgba(0, 0, 0, 1);--wp--preset--shadow--crisp:6px 6px 0px rgba(0, 0, 0, 1);--wp--preset--duotone--dark-grayscale:url(#wp-duotone-dark-grayscale);--wp--preset--duotone--grayscale:url(#wp-duotone-grayscale);--wp--preset--duotone--purple-yellow:url(#wp-duotone-purple-yellow);--wp--preset--duotone--blue-red:url(#wp-duotone-blue-red);--wp--preset--duotone--midnight:url(#wp-duotone-midnight);--wp--preset--duotone--magenta-yellow:url(#wp-duotone-magenta-yellow);--wp--preset--duotone--purple-green:url(#wp-duotone-purple-green);--wp--preset--duotone--blue-orange:url(#wp-duotone-blue-orange)}@media (min-resolution:192dpi){:root{--wp-admin-border-width-focus:1.5px}}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Oxygen-Sans,Ubuntu,Cantarell,Helvetica Neue,sans-serif;font-size:18px;line-height:1.5;--wp--style--block-gap:2em}p{line-height:1.8}.editor-post-title__block{font-size:2.5em;font-weight:800;margin-bottom:1em;margin-top:2em}.wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none}.has-black-color{color:var(--wp--preset--color--black)!important}.has-cyan-bluish-gray-color{color:var(--wp--preset--color--cyan-bluish-gray)!important}.has-white-color{color:var(--wp--preset--color--white)!important}.has-pale-pink-color{color:var(--wp--preset--color--pale-pink)!important}.has-vivid-red-color{color:var(--wp--preset--color--vivid-red)!important}.has-luminous-vivid-orange-color{color:var(--wp--preset--color--luminous-vivid-orange)!important}.has-luminous-vivid-amber-color{color:var(--wp--preset--color--luminous-vivid-amber)!important}.has-light-green-cyan-color{color:var(--wp--preset--color--light-green-cyan)!important}.has-vivid-green-cyan-color{color:var(--wp--preset--color--vivid-green-cyan)!important}.has-pale-cyan-blue-color{color:var(--wp--preset--color--pale-cyan-blue)!important}.has-vivid-cyan-blue-color{color:var(--wp--preset--color--vivid-cyan-blue)!important}.has-vivid-purple-color{color:var(--wp--preset--color--vivid-purple)!important}.has-black-background-color{background-color:var(--wp--preset--color--black)!important}.has-cyan-bluish-gray-background-color{background-color:var(--wp--preset--color--cyan-bluish-gray)!important}.has-white-background-color{background-color:var(--wp--preset--color--white)!important}.has-pale-pink-background-color{background-color:var(--wp--preset--color--pale-pink)!important}.has-vivid-red-background-color{background-color:var(--wp--preset--color--vivid-red)!important}.has-luminous-vivid-orange-background-color{background-color:var(--wp--preset--color--luminous-vivid-orange)!important}.has-luminous-vivid-amber-background-color{background-color:var(--wp--preset--color--luminous-vivid-amber)!important}.has-light-green-cyan-background-color{background-color:var(--wp--preset--color--light-green-cyan)!important}.has-vivid-green-cyan-background-color{background-color:var(--wp--preset--color--vivid-green-cyan)!important}.has-pale-cyan-blue-background-color{background-color:var(--wp--preset--color--pale-cyan-blue)!important}.has-vivid-cyan-blue-background-color{background-color:var(--wp--preset--color--vivid-cyan-blue)!important}.has-vivid-purple-background-color{background-color:var(--wp--preset--color--vivid-purple)!important}.has-black-border-color{border-color:var(--wp--preset--color--black)!important}.has-cyan-bluish-gray-border-color{border-color:var(--wp--preset--color--cyan-bluish-gray)!important}.has-white-border-color{border-color:var(--wp--preset--color--white)!important}.has-pale-pink-border-color{border-color:var(--wp--preset--color--pale-pink)!important}.has-vivid-red-border-color{border-color:var(--wp--preset--color--vivid-red)!important}.has-luminous-vivid-orange-border-color{border-color:var(--wp--preset--color--luminous-vivid-orange)!important}.has-luminous-vivid-amber-border-color{border-color:var(--wp--preset--color--luminous-vivid-amber)!important}.has-light-green-cyan-border-color{border-color:var(--wp--preset--color--light-green-cyan)!important}.has-vivid-green-cyan-border-color{border-color:var(--wp--preset--color--vivid-green-cyan)!important}.has-pale-cyan-blue-border-color{border-color:var(--wp--preset--color--pale-cyan-blue)!important}.has-vivid-cyan-blue-border-color{border-color:var(--wp--preset--color--vivid-cyan-blue)!important}.has-vivid-purple-border-color{border-color:var(--wp--preset--color--vivid-purple)!important}.has-vivid-cyan-blue-to-vivid-purple-gradient-background{background:var(--wp--preset--gradient--vivid-cyan-blue-to-vivid-purple)!important}.has-light-green-cyan-to-vivid-green-cyan-gradient-background{background:var(--wp--preset--gradient--light-green-cyan-to-vivid-green-cyan)!important}.has-luminous-vivid-amber-to-luminous-vivid-orange-gradient-background{background:var(--wp--preset--gradient--luminous-vivid-amber-to-luminous-vivid-orange)!important}.has-luminous-vivid-orange-to-vivid-red-gradient-background{background:var(--wp--preset--gradient--luminous-vivid-orange-to-vivid-red)!important}.has-very-light-gray-to-cyan-bluish-gray-gradient-background{background:var(--wp--preset--gradient--very-light-gray-to-cyan-bluish-gray)!important}.has-cool-to-warm-spectrum-gradient-background{background:var(--wp--preset--gradient--cool-to-warm-spectrum)!important}.has-blush-light-purple-gradient-background{background:var(--wp--preset--gradient--blush-light-purple)!important}.has-blush-bordeaux-gradient-background{background:var(--wp--preset--gradient--blush-bordeaux)!important}.has-luminous-dusk-gradient-background{background:var(--wp--preset--gradient--luminous-dusk)!important}.has-pale-ocean-gradient-background{background:var(--wp--preset--gradient--pale-ocean)!important}.has-electric-grass-gradient-background{background:var(--wp--preset--gradient--electric-grass)!important}.has-midnight-gradient-background{background:var(--wp--preset--gradient--midnight)!important}.has-small-font-size{font-size:var(--wp--preset--font-size--small)!important}.has-medium-font-size{font-size:var(--wp--preset--font-size--medium)!important}.has-large-font-size{font-size:var(--wp--preset--font-size--large)!important}.has-x-large-font-size{font-size:var(--wp--preset--font-size--x-large)!important}:where(.wp-block-columns.is-layout-flex){gap:2em}:where(.wp-block-columns.is-layout-grid){gap:2em}:where(.wp-block-post-template.is-layout-flex){gap:1.25em}:where(.wp-block-post-template.is-layout-grid){gap:1.25em}:where(.is-layout-flex){gap:.5em}:where(.is-layout-grid){gap:.5em}.is-layout-constrained>.alignleft,.is-layout-flow>.alignleft{float:left;margin-inline-start:0;margin-inline-end:2em}.is-layout-constrained>.alignright,.is-layout-flow>.alignright{float:right;margin-inline-start:2em;margin-inline-end:0}.is-layout-constrained>.aligncenter,.is-layout-flow>.aligncenter{margin-left:auto!important;margin-right:auto!important}.is-layout-constrained>:where(:not(.alignleft):not(.alignright):not(.alignfull)){max-width:var(--wp--style--global--content-size);margin-left:auto!important;margin-right:auto!important}.is-layout-constrained>.alignwide{max-width:var(--wp--style--global--wide-size)}body .is-layout-flex{display:flex}.is-layout-flex{flex-wrap:wrap;align-items:center}.is-layout-flex>:is(*,div){margin:0}body .is-layout-grid{display:grid}.is-layout-grid>:is(*,div){margin:0}:root :where(.editor-styles-wrapper)::after{content:"";display:block;height:40vh}:where(.block-editor-iframe__body){display:flow-root}.is-root-container{display:flow-root}

Answer 2

Where to look, If it seems that all styles are removed

You should check if bootstrap is overridden?

Prevent your CSS from Overriding Bootstrap

If your custom css " editor-style.css has rules like this:"

body {
    font-size: 16px;
    line-height: 1.5;
}

Replace OR Change with:

.editor-styles-wrapper {
    font-size: 16px;
    line-height: 1.5;
}

This make Sure that your styles only affect the content area, not the entire editor UI.

You should also consider restoring Bootstrap Box Model

Bootstrap sets box-sizing: border-box globally, but WordPress expects content-box in some editor parts. here is the Fix

/* Reset box-sizing only for editor UI */
.editor-styles-wrapper * {
    box-sizing: content-box;
}

/* But keep border-box for content (if needed) */
.editor-styles-wrapper .wp-block,
.editor-styles-wrapper p,
.editor-styles-wrapper h1, 
.editor-styles-wrapper h2 {
    box-sizing: border-box;
}

If Bootstrap is loaded first, your styles might not apply correctly. Ensure your editor-style.css loads after Bootstrap:

function editor_style() {
    add_theme_support('editor-styles');
    add_editor_style([
        'https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css', // Bootstrap first
        'editor-style.css' // Your overrides last
    ]);
}
add_action('after_setup_theme', 'editor_style');

I hope this will resolve your issue.