* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Poppins", sans-serif;
}

:root {
    --bgcolor: #0C101E;
    --btncolor: #0c101e5b;
    --txtcolor: #fff;
    --box-shadow: 2px 2px 4px 0px #1B2031 inset;
    --filter: drop-shadow(2px 2px 8px #020305);
    --border: 1px solid transparent;
}

.light {
    --bgcolor: #F4F4F4;
    --btncolor: #f4f4f485;
    --txtcolor: #0C101E;
    --box-shadow: none;
    --filter: none;
    --border: 1px solid #0C101E;
}

body {
    width: 100%;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    width: 23.75rem;
    height: 43.75rem;
    background-color: var(--bgcolor);
    border-radius: 2.1rem;
    padding: 1.4rem 1.6rem;
    display: flex;
    align-items: center;
    flex-direction: column;
    gap: 1.2rem;
    position: relative;
    border: var(--border);
}

#modebtn {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background-color: #F4F4F4;
    right: 1.2rem;
    cursor: pointer;
    position: absolute;
    display: flex;
    justify-content: center;
    align-items: center;
}

#modebtn.light-btn {
    background-color: #0C101E;
}

.screen-box {
    width: 100%;
    height: 35%;
    border-radius: 1.2rem 1.2rem 0 0;
}

#screen {
    width: 100%;
    height: 100%;
    outline: none;
    border: none;
    text-align: end;
    display: flex;
    background-color: var(--bgcolor);
    border-radius: 1.2rem 1.2rem 0 0;
    font-size: 2.7rem;
    color: var(--txtcolor);
    caret-color: var(--txtcolor);
    padding: 0.8rem;
    padding-top: 9rem;
    letter-spacing: 3px;
}

.btn-container {
    flex: 1;
    width: 100%;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    /* grid-template-rows: repeat(5, 1fr); */
    grid-gap: 1rem;
}

#zero {
    grid-column: span 2;
    border-radius: 50px;
    width: 9.75rem;
    height: 4.375rem;
}

button {
    border: none;
    outline: none;
    width: 4.375rem;
    height: 4.375rem;
    border-radius: 50%;
    background-color: var(--btncolor);
    color: var(--txtcolor);
    font-size: 20px;
    font-weight: 600;
    cursor: pointer;
    box-shadow: var(--box-shadow);
    filter: var(--filter);
    border: var(--border);
}