body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #1a001f, #6a0dad);
    font-family: Arial, sans-serif;
    margin: 0;
    color: white;
}

.calculator-container {
    background: rgba(20,20,20,0.9);
    padding: 40px;
    border-radius: 20px;
    border: 2px solid #bb86fc;
    box-shadow: 0 0 30px rgba(187,134,252,0.7);
    text-align: center;
    max-width: 300px;
    width: 90%;
}

.calculator-container h1 {
    color: #bb86fc;
    margin-bottom: 10px;
}

#history-container {
    display: flex;
    flex-direction: column-reverse; /* newest on top */
    align-items: flex-end;
    min-height: 50px;
    margin-bottom: 10px;
}

.history-item {
    font-size: 0.9rem;
    color: #bb86fc;
    margin-bottom: 3px;
    animation: moveUp 0.4s ease forwards;
}

@keyframes moveUp {
    0% { transform: scale(1.2) translateY(0); opacity:0; }
    100% { transform: scale(0.8) translateY(-10px); opacity:1; }
}

#display {
    width: 100%;
    padding: 10px;
    font-size: 1.5rem;
    margin-bottom: 20px;
    border-radius: 10px;
    border: none;
    text-align: right;
    background: #0f0f0f;
    color: #fff;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

button {
    width: 60px;       /* same width and height */
    height: 60px;
    font-size: 1.2rem;
    border-radius: 50%; /* makes it circular */
    border: none;
    background: #141414;
    color: white;
    cursor: pointer;
    transition: 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

button:hover {
    background: #6a0dad;
    box-shadow: 0 5px 15px rgba(187,134,252,0.5);
}

.design-btn {
    background: #9a40cf;
}