:root {
    --bg-color: #2c2c2c;
    --calc-bg: #000000;
    --btn-color: #333333;
    --btn-hover: #4d4d4d;
    --op-color: #ff9f0a;
    --op-hover: #ffb546;
    --text-white: #ffffff;
    --control-color: #a5a5a5;
    --control-text: #000000;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: var(--bg-color);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

.calc {
    background-color: var(--calc-bg);
    width: 320px;
    padding: 20px;
    border-radius: 30px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.display {
    background-color: transparent;
    color: var(--text-white);
    font-size: 4rem;
    text-align: right;
    padding: 10px 20px;
    overflow: hidden;
    margin-bottom: 10px;
    font-weight: 300;
}

.calc-body {
    display: flex;
    gap: 15px;
}

.btnNums {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    flex-grow: 1;
}

.ops {
    display: flex;
    flex-direction: column;
    gap: 12px;
    width: 70px;
}

.controls {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

button {
    border: none;
    border-radius: 50%;
    height: 70px;
    width: 70px;
    font-size: 1.5rem;
    font-weight: 500;
    cursor: pointer;
    transition: filter 0.2s;
    color: var(--text-white);
    background-color: var(--btn-color);
}

button:active {
    filter: brightness(130%);
}

.btnNums button {
    background-color: var(--btn-color);
}
.btnNums button:hover {
    background-color: var(--btn-hover);
}

.zero {
    grid-column: span 2;
    width: 100% !important;
    border-radius: 35px !important;
    text-align: left;
    padding-left: 28px;
}

.ops button {
    background-color: var(--op-color);
    font-size: 2rem;
}
.ops button:hover {
    background-color: var(--op-hover);
}

.controls button {
    background-color: var(--control-color);
    color: var(--control-text);
    width: 100%; 
    border-radius: 35px;
}
.controls button:hover {
    background-color: #d4d4d2;
}