* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(135deg,
        #050b1f,
        #0b1f3a,
        #123a63,
        #1b4f8a,
        #0a0f2e
    );
    font-family: Arial, Helvetica, sans-serif;
}
.calculator {
    width: 95%;
    max-width: 420px;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 15px 35px rgba(0,0,0,.35);
}
.screen {
    background: #6c6a86;
    min-height: 100px;
    padding: 15px 20px;
    border-radius: 10px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    margin-bottom: 16px;
    color: white;
    box-shadow: inset 3px 3px 10px rgba(0,0,0,.3);
}
.screen-history {
    font-size: 16px;
    color: rgba(255,255,255,.65);
    min-height: 20px;
    overflow-x: auto;
    margin-bottom: 8px;
}
.screen-result {
    font-size: 42px;
    font-weight: 700;
    overflow-x: auto;
}
.screen-history::-webkit-scrollbar,
.screen-result::-webkit-scrollbar {
    display: none;
}
.buttons {
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.buttons-row {
    display: flex;
    gap: 10px;
}
.button {
    flex: 1;
    height: 60px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 20px;
    color: white;
    background: #565574;
    transition: .2s;
}
.button:hover {
    background: #7877a0;
    transform: translateY(-3px);
}
.button:active {
    transform: scale(.95);
}
.button-equal {
    background: linear-gradient(135deg, #7e154d, #791037);
}