**Title: "Birthday Grapple: A Jiu-Jitsu Celebration"**

**Background:**

The background is a simple, clean gradient transitioning from a light sky blue at the top to a deeper blue at the bottom. This gradient serves as a subtle nod to a dojo mat and creates a sense of depth without distraction.

**Main Scene:**

At the center of the card, two cartoonish characters are engaged in a friendly jiu-jitsu bout. They are mid-action, with exaggerated poses to emphasize movement and energy. The characters are depicted in a flat vector style with crisp, clean lines, capturing the dynamic essence of jiu-jitsu.

1. **Character Details:**

- The character on the left wears a bright white gi with a blue belt, symbolizing the progression of skill. The gi has a subtle texture, indicated by light gray dashed lines, to suggest fabric folds.

- The character on the right sports a vibrant blue gi with a purple belt, representing a slightly more advanced level. Similar dashed lines are used for texture.

- Both characters have stylized, oval heads with small dot eyes and line mouths, adding a humorous touch. They have different skin tones to reflect diversity.

2. **Action Elements:**

- The character on the left is executing a playful leg sweep, with one leg extended outward in a sweeping motion. His other arm is bent at the elbow for balance.

- The character on the right is slightly airborne, arms flailing comically, with exaggerated curved lines emanating from his body to indicate motion and surprise.

- Both characters have simplistic hands and feet, with three fingers and toes each, enhancing the whimsical cartoonish style.

**Foreground Elements:**

- Scattered around the characters are stylized flat shapes representing confetti and streamers in bright colors like red, yellow, and green. These shapes add a festive touch to the scene and frame the characters.

- A cartoonish, flat shape birthday cake is positioned in the bottom left corner. The cake is a simple two-tier design, with pastel pink frosting and colorful sprinkles. Three small, flat, orange candles with yellow flames sit atop the cake.

**Additional Details:**

- At the top of the card, arched in a playful font, are the words "HAPPY BIRTHDAY!" in bold, white letters with a thin black outline, ensuring legibility against the blue gradient.

- The bottom right corner features a small, flat vector image of a jiu-jitsu belt tied in a knot, symbolizing the bond and connection formed through the martial art.

This composition combines humor and style, with clear, bold colors and elements that capture the celebratory nature of a birthday intertwined with the spirit of jiu-jitsu.

Generated with these themes: Jui jitsu.

Made with ❤️ by AI.