body {
    background-color: #111;
    color: #fff;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    font-family: sans-serif;
    perspective: 1000px;
}

.tool-container {
    text-align: center;
}

.card-scene {
    width: 300px;
    height: 450px;
    margin: 0 auto 30px;
}

.card {
    width: 100%;
    height: 100%;
    transition: transform 1s;
    transform-style: preserve-3d;
    cursor: pointer;
    position: relative;
}

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

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border-radius: 15px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

.card-front {
    background: linear-gradient(135deg, #00bcd4, #2196f3);
    color: #fff;
}

.card-back {
    background: #fff;
    color: #111;
    transform: rotateY(180deg);
    padding: 20px;
}

.card-logo {
    font-size: 0.8rem;
    letter-spacing: 2px;
    margin-bottom: 20px;
    opacity: 0.8;
}

.card-title {
    font-size: 2rem;
    font-weight: bold;
    text-align: center;
    line-height: 1.2;
}

.card-instruction {
    margin-top: 30px;
    font-size: 0.7rem;
    opacity: 0.6;
}

.strategy-text {
    font-size: 1.5rem;
    font-weight: bold;
    line-height: 1.5;
    word-break: keep-all;
}

.btn {
    background: transparent;
    border: 1px solid #fff;
    color: #fff;
    padding: 10px 20px;
    cursor: pointer;
    transition: all 0.3s;
}

.btn:hover {
    background: #fff;
    color: #000;
}

.link-back {
    display: block;
    margin-top: 20px;
    color: #888;
    text-decoration: none;
    font-size: 0.8rem;
}