style.css

body {
    font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", "Open Sans",
    serif;
    font-size: 27px;
    margin: 0;
    box-sizing: border-box;
    padding: 0;
    -webkit-appearance: none;
    --background-color: rgb(19, 18, 18);
    --accent-color: rgb(23, 49, 19);
    background-color: var(--background-color);
    height: 100vh;
    width: 100%;
    display: flex;
    justify-content: center;
    flex-direction: column;
    align-items: center;
}

.inner-box {
    max-width: 385px;
    display: flex;
    flex-direction: column;
    justify-content: space-around;
    align-items: center;
    padding: 25px 15px;
    border-radius: 20px;
    outline: rgb(44, 46, 45) 5px solid;
}

::placeholder {
    color: black;
    opacity: 1;
}

input {
    font-weight: bold;
    transition: all ease-in 120ms;
    display: inline-block;
    color: rgb(255, 255, 255);
    font-size: 1.3em;
    text-align: center;
    cursor: pointer;
    height: 100%;
    width: 100%;
    background-color: rgb(47, 51, 50);
    border: none;
    outline: white;
    border-radius: 17px;
}

.inner-box .row {
    width: 100%;
    display: flex;
    flex-grow: 1;
}

input:disabled {
    transition: none !important;
    opacity: 40% !important;
    cursor: not-allowed !important;
}

.btn-wrapper {
    display: inline-block;
    flex-grow: 1;
    flex-basis: 25%;
    padding: 1.8%;
    aspect-ratio: 1/1;
    max-height: 9vh;
}

input[type="text"] {
    background-color: rgb(172, 180, 177);
    font-size: 1.5em;
    text-align: end;
    color: black;
    cursor: default;
    padding: 16px 15px 16px 3px;
    margin-bottom: 18px;
    box-shadow: 0 0 2px 3px inset rgb(47, 51, 50);
}

input[type="button"] {
    cursor: pointer;
    opacity: 100%;
}

input[type="button"]:hover {
    opacity: 85%;
}

.accent_button {
    background-color: var(--accent-color);
}

#clear_button {
    background-color: #621515;
}

#memory_read_button {
    background-color: #544210;
}

*.unselectable {
    -moz-user-select: -moz-none;
    -khtml-user-select: none;
    -webkit-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

@media screen and (max-width: 375px), screen and (max-height: 624px) {
    .inner-box {
        font-size: 6vmin;
    }

    input[type="text"] {
        font-size: 8vmin;
        padding: 3vmin 4vmin 3vmin 3px;
    }
}

@media screen and (max-width: 422px), screen and (max-height: 624px) {
    .inner-box {
        outline: none;
    }
}

/* Loader */

.loader-container {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    position: fixed;
    background: var(--background-color);
    z-index: 1;
}

.spinner {
    width: 2.5em;
    height: 2.5em;
    border: 7px solid #3d3d3d;
    border-bottom-color: #47bd30;
    border-radius: 50%;
    display: inline-block;
    box-sizing: border-box;
    animation: rotation 1s infinite;
}

@keyframes rotation {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}