DevToolBox

CSS Generator

Box Shadow, Border Radius, Gradientをビジュアルに生成。リアルタイムプレビュー付き。

#000000
box-shadow: 4px 4px 10px 0px #000000;

How to Use the CSS Generator

The CSS Generator is a free online visual tool that helps web developers and designers create CSS properties without writing code manually. It features three powerful modules: Box Shadow, Border Radius, and Gradient generators, each with intuitive slider controls and real-time preview. All CSS code is generated instantly as you adjust the controls, and you can copy the output with a single click. This tool runs entirely in your browser with no external dependencies or server communication required.

Box Shadow Generator

The CSS box-shadow property adds shadow effects around an element. It accepts values for horizontal offset, vertical offset, blur radius, spread radius, and color. The inset keyword creates an inner shadow instead of the default outer shadow. Box shadows are one of the most commonly used CSS properties for adding depth and visual hierarchy to web interfaces. They can simulate elevation in Material Design, create neumorphic effects, add focus indicators for accessibility, and provide subtle depth cues that guide user attention. Multiple box shadows can be layered for more complex effects, and they can be animated with CSS transitions for interactive hover states and focus effects.

Border Radius Generator

The CSS border-radius property rounds the corners of elements. It can accept a single value that applies to all four corners equally, or four individual values for the top-left, top-right, bottom-right, and bottom-left corners respectively. Border radius is fundamental to modern web design, used for creating rounded buttons, pill-shaped tags, circular avatars (with 50% radius), card components, and soft UI elements. The linked mode in this tool lets you adjust all corners simultaneously for uniform rounding, while the unlinked mode gives you independent control over each corner for asymmetric designs.

CSS Border Generator

The CSS border property combines width, style, and color into a single declaration for an element's outline. Common border styles include solid, dashed, dotted, and double, each suited to different visual contexts from simple dividers to decorative frames. Borders are essential for form inputs, cards, tables, and focus states, and can be combined with border-radius for rounded bordered elements. For a gradient border effect, use a transparent border with a layered background:

.gradient-border {
  border: 4px solid transparent;
  background:
    linear-gradient(white, white) padding-box,
    linear-gradient(135deg, #6366f1, #8b5cf6) border-box;
}

CSS Gradient Generator

CSS gradients create smooth transitions between two or more colors. Linear gradients flow in a straight line at a specified angle, while radial gradients emanate from a central point outward. Gradients are widely used for backgrounds, overlays, buttons, progress bars, and decorative elements. They eliminate the need for gradient images, reducing page load times and enabling resolution-independent designs that look sharp on all screen densities. The angle control for linear gradients lets you create horizontal (90deg), vertical (180deg), diagonal (45deg), and any custom direction. CSS gradients are supported in all modern browsers and are a cornerstone of contemporary web design.

CSS Generatorの使い方

このCSS Generatorは、Box Shadow(影)、Border Radius(角丸)、Gradient(グラデーション)の CSSプロパティをビジュアルに生成する無料オンラインツールです。スライダーやカラーピッカーを操作すると リアルタイムでプレビューが更新され、生成されたCSSコードをワンクリックでコピーできます。 全ての処理はブラウザ内で完結し、外部ライブラリやサーバー通信は一切不要です。 Webデザインやフロントエンド開発の効率化にお役立てください。

CSS Border Generator(枠線ジェネレーター)

CSSのborderプロパティは、枠線の幅・スタイル・色を1つの宣言で指定でき、フォーム入力、カード、 テーブル、フォーカス状態などの表現に役立ちます。実線、破線、点線、二重線などを用途に応じて選び、 border-radiusと組み合わせれば角丸の枠線も作成できます。グラデーション枠線には、透明なborderと padding-box・border-boxを指定した2層のbackgroundを重ねる方法や、border-imageにグラデーションを 指定する方法があります。

よくある落とし穴と対処 / Common Pitfalls

落とし穴 / Pitfall問題 / Problem対処 / Fix
多層shadowの記述順
Multi-layer shadow order
box-shadowはカンマ区切りで重ねられ、先に書いたものが上に描画される
Earlier shadows paint on top
強い影→淡い影の順に重ねると自然な立体感になる
Stack sharp-to-soft for natural depth
影が切れる
Shadows get clipped
親要素の overflow: hidden で影が見切れる
Parent overflow:hidden clips shadows
影の広がり分のpadding確保か、overflow を見直す
Add padding or rethink overflow
グラデの縞模様(バンディング)
Gradient banding
近い色同士の長いグラデで段差が見える
Long subtle gradients show bands
中間色を1つ挟む、または角度を変えて距離を短くする
Add a midpoint stop
box-shadowでレイアウトが動くと誤解
Expecting shadows to affect layout
影はレイアウト計算に含まれない(隣要素は動かない)
Shadows don't take layout space
意図的な余白は margin で確保する
Use margins for spacing
角丸が円にならない
border-radius 50% not circular
要素が正方形でないと 50% は楕円になる
50% on a rectangle gives an ellipse
幅と高さを揃える(aspect-ratio: 1 が便利)
Make the element square first

生成例 / Example Output

/* カード用のソフトシャドウ(2層重ね) */
box-shadow: 0 1px 3px rgba(0,0,0,0.12),
            0 8px 24px rgba(0,0,0,0.08);

/* ブランドグラデーション */
background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);

Why browser-only?

Visual CSS tweaking needs instant feedback, not a server round-trip. This generator renders previews and builds the CSS string entirely in your browser — design values for unreleased UI never leave your machine, and the tool works offline. Combine it with our Color Palette Generator for gradient color picks.

プレビューもコード生成も全てブラウザ内で完結します。グラデーションの配色選びはColor Palette Generator、 コントラスト確認はContrast Checkerをどうぞ。

関連ツール / Related Tools

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