style.css

* {
    background-color: rgb(216, 216, 216);
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    outline: none;
    border: none;
    text-decoration: none;
}

body {
    display: grid;
    place-items: center;
    background-color: black;
    height: 100vh;
    overflow: hidden;
}

main {
    display: flex;
    flex-direction: column;
    align-items: center;
    box-shadow: 0px -1px 15px rgba(0, 0, 0, 0.854) inset;
    border-radius: 4% 4% 12% 12%;
    height: 95vh;
    width: 50vh;
    position: absolute;
    margin: auto;
}

@media(width<500px) {
    main {
        top: 0%;
        height: 92vh;
        width: 48vh;
    }
}

.heading {
    background-color: transparent;
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-rows: repeat(3, 1fr);
    height: 9.5%;
    width: 80%;
    margin: .5vh 0px 1vh 0px;
}

.brand {
    background-color: transparent;
    font-weight: bolder;
    font-family: 'Courier New', Courier, monospace;
    font-size: 1.375rem;
    text-align: center;
}

.model {
    background-color: transparent;
    font-size: 0.625rem;
    font-style: italic;
    grid-column: 1;
    grid-row: 2/3;
}

.headingtext1 {
    background-color: transparent;
    font-size: 0.625rem;
    grid-column: 1;
    grid-row: 3/4;
    color: #07a293;
    font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
    font-weight: bolder;
    font-style: italic;
}

.headingtext2 {
    background-color: transparent;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    font-size: 0.4375rem;
    grid-column: 2;
    grid-row: 3/4;
    text-align: right;
    margin: .5vh 5px 0px 0px;
}

.solar {
    grid-column: 2;
    grid-row: 1/3;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: 1fr;
    grid-gap: 1.5px;
    border: 2px solid black;
    border-radius: 10px;
    width: 100%;
    height: 100%;
    background-color: rgb(168, 164, 164);
}

.solar div {
    background-color: rgb(150, 142, 142);
    box-shadow: 0px -1px 15px rgba(74, 70, 70, 0.854) inset;
}

.solar div:first-child {
    border-radius: 25% 0px 0px 25%;
}

.solar div:last-child {
    border-radius: 0px 25% 25% 0px;
}

.displayarea {
    width: 80%;
    height: 16%;
    display: flex;
    justify-content: center;
    position: relative;
}

.display {
    outline: 1px solid rgba(74, 70, 70, 0.639);
    outline-offset: 5px;
    box-shadow: 0px -1px 15px rgba(13, 53, 38, 0.945) inset;
    border-radius: 6px;
    background-color: rgb(166, 191, 172);
    width: 100%;
    cursor: text;
    resize: none;
    padding: 10px 8px;
    font-family: 'Courier New', Courier, monospace;
    font-weight: bold;
    font-size: 1.25rem;
    overflow: hidden;
}

.buttonarea1 {
    background-color: transparent;
    margin-top: 1vh;
    height: calc((100% - 25.5% - 30px)/2);
    width: 90%;
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    grid-template-rows: repeat(5, 1fr);
    place-items: center;
}

.button1 {
    background: linear-gradient(#464545, #323232);
    box-shadow: 0px 1px 4px rgba(0, 0, 0, 0.854);
    border-radius: 5px 5px 40% 40%;
    height: 3.36vh;
    width: 5.37vh;
    cursor: pointer;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 0.625rem;
}

#replay {
    grid-column: 3/5;
    grid-row: 1/3;
    background-color: #a3b9d8;
    box-shadow: 0px -1px 25px #798fb0 inset;
    outline: 2px solid #798fb0;
    border: 1px solid #a3b9d8;
    width: 90%;
    height: 80%;
    border-radius: 100%;
    cursor: pointer;
    text-align: center;
    font-size: 0.5rem;
    font-weight: bold;
    color: #5e7597;
    padding-top: 30%;
}

.buttonarea2 {
    background-color: transparent;
    margin: 0px 0px 2vh 0px;
    height: calc((100% - 25.5% - 30px)/2);
    width: 90%;
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    grid-template-rows: repeat(4, 1fr);
    place-items: center;
}

.button2 {
    background-color: rgb(255, 255, 255);
    box-shadow: 0px 1px 4px rgba(0, 0, 0, 0.854);
    border-radius: 5px 5px 45% 45%;
    height: 4.2vh;
    width: 6.72vh;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.0625rem;
    font-weight: bold;
    font-family: Arial, Helvetica, sans-serif;
}

.button1:active,
.button2:active,
.button3:active {
    box-shadow: 0px 0.5px 3px rgba(0, 0, 0, 0.854);
}

.button3 {
    background: linear-gradient(#aabcdb, #798fb0);
    box-shadow: 0px 1px 4px rgba(0, 0, 0, 0.854);
    border-radius: 5px 5px 40% 40%;
    height: 3.36vh;
    width: 5.37vh;
    cursor: pointer;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 0.5rem;
}

#del,
#ac {
    background-color: rgb(248, 100, 8);
}

#casiotext {
    background-color: transparent;
    font-weight: bolder;
    font-family: 'Courier New', Courier, monospace;
    font-size: 3.125rem;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

#caret {
    width: 5px;
    height: 20px;
    background-color: black;
    animation: caret 0.5s alternate infinite;
    animation-delay: 2s;
    position: absolute;
    top: 14%;
    left: 3%;
}

@keyframes fadein {
    0% {
        opacity: 1;
    }

    70% {
        opacity: 1;
    }

    100% {
        opacity: 0;
    }
}

@keyframes caret {
    0% {
        opacity: 1;
    }

    100% {
        opacity: 0;
    }
}