body {
    font-family:sans-serif;
    display: flex;
    justify-content:center;
    align-items: center;
    height: 100vh;
    background: green;
    margin: 0;
    overflow: hidden;
}

.flashcard-container {
    text-align: center;
    background-color: white;
    padding: 40px;
    border-radius: 20px;
}

.flashcard {
    width: 90%;
    height: 100px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    margin: 0 auto;
}

.flashcard.is-flipped {
    transform: rotateY(180deg);
}

.flashcard div {
    position: absolute;
    width: 100%;
    height: 70%;
    backface-visibility: hidden;
    border-radius: 15px;
    background: linear-gradient(135deg, #f5f7fa, #c3cfe2);
    display: flex;
    padding: 20px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    font-size: 1.1em;
}

.back {
    transform: rotateY(180deg);
}

button {
    margin: 10px;
    padding: 12px 25px;
    border: none;
    border-radius: 25px;
    font-size: 1.1em;
    cursor: pointer;
    background-color: rgb(127, 233, 127);
    transition: background-color 0.3s, transform 0.2s;
}

button:hover {
    background-color: green;
}

button:active {
   transform: scale(0.95);
}