@import url("https://fonts.googleapis.com/css2?family=Poppins:ital,wght@0,700;1,400;1,800&display=swap");
* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
:root {
    --primary-clr: hsl(0, 1%, 44%);
    --header-clr: hsl(0, 0%, 8%);
    --body-bg: hsl(0, 0%, 94%);
    --main-bg: hsl(0, 0%, 100%);
    --border-bg: hsl(0, 0%, 86%);
    --cta: hsl(259, 100%, 65%);
    --error: hsl(0, 100%, 67%);

    --fs-xs: 12px;
    --fs-s: 18px;
    --fs-l: 2.5rem;
}
body {
    /* min-height: 100vh; */
    background: var(--body-bg);
    font-size: var(--fs-xs);
    font-family: "Poppins", sans-serif;
    font-style: italic;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
main {
    background: var(--main-bg);
    padding: 1.5rem;
    margin: 1rem;
    -webkit-border-radius: 1.5rem 1.5rem 5rem 1.5rem;
    -moz-border-radius: 1.5rem 1.5rem 5rem 1.5rem;
    -ms-border-radius: 1.5rem 1.5rem 5rem 1.5rem;
    -o-border-radius: 1.5rem 1.5rem 5rem 1.5rem;
    border-radius: 1.5rem 1.5rem 5rem 1.5rem;
    box-shadow: 0 5px 5px 0 rgba(0, 0, 0, 0.05);
}
main form {
    position: relative;
}
form .input-container {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    align-items: start;
    gap: 1rem;
    padding-bottom: 3rem;
    border-bottom: 1px solid var(--border-bg);
}
.input-field {
    display: grid;
}
.input-field > * {
    width: 100%;
}
.input-field .label {
    color: var(--primary-clr);
    font-weight: 700;
    font-style: normal;
    text-transform: uppercase;
    letter-spacing: 3px;
}
.input-field.empty-value .label,
.input-field.invalid-value .label {
    color: var(--error);
}
.input-field .input {
    height: 3rem;
    color: var(--header-clr);
    font-size: var(--fs-s);
    font-weight: 700;
    font-family: "Poppins", sans-serif;
    padding-left: 1rem;
    margin: 0.5rem 0;
    outline: none;
    border: 1px solid var(--border-bg);
    -webkit-border-radius: 0.5rem;
    -moz-border-radius: 0.5rem;
    -ms-border-radius: 0.5rem;
    -o-border-radius: 0.5rem;
    border-radius: 0.5rem;
    -webkit-transition: all 0.2s linear;
    -moz-transition: all 0.2s linear;
    -ms-transition: all 0.2s linear;
    -o-transition: all 0.2s linear;
    transition: all 0.2s linear;
}
.input::placeholder {
    font-size: var(--fs-s);
    font-weight: 700;
    font-family: "Poppins", sans-serif;
}
.input-field .input:focus {
    border: 1px solid var(--cta);
}
.input-field.empty-value .input,
.input-field.invalid-value .input {
    border: 1px solid var(--error);
}
.empty,
.invalid {
    color: var(--error);
    display: none;
}
.input-field.empty-value .empty {
    display: initial;
}
.input-field.invalid-value .invalid {
    display: initial;
}
form .submit-btn {
    position: absolute;
    bottom: -25px;
    left: 0;
    right: 0;
    margin-inline: auto;
    width: 50px;
    height: 50px;
    background: var(--cta);
    display: grid;
    place-items: center;
    outline: none;
    border: none;
    padding: 0.5rem;
    -webkit-border-radius: 50%;
    -moz-border-radius: 50%;
    -ms-border-radius: 50%;
    -o-border-radius: 50%;
    border-radius: 50%;
    cursor: pointer;
    -webkit-transition: all 0.2s linear;
    -moz-transition: all 0.2s linear;
    -ms-transition: all 0.2s linear;
    -o-transition: all 0.2s linear;
    transition: all 0.2s linear;
    -webkit-animation: spin 3s linear infinite;
    animation: spin 3s linear infinite;
}
@keyframes spin {
    0% {
        -webkit-transform: rotate(0);
        -moz-transform: rotate(0);
        -ms-transform: rotate(0);
        -o-transform: rotate(0);
        transform: rotate(0);
    }
    100% {
        -webkit-transform: rotate(360deg);
        -moz-transform: rotate(360deg);
        -ms-transform: rotate(360deg);
        -o-transform: rotate(360deg);
        transform: rotate(360deg);
    }
}
.submit-btn:hover {
    background: var(--header-clr);
}
.submit-btn img {
    width: 20px;
    height: 20px;
}
main .age-container {
    padding: 3rem 0 1rem 0;
}
.age-container .age {
    color: var(--header-clr);
    font-size: var(--fs-l);
    font-weight: 800;
    line-height: 1.2;
}
.age span,
footer a {
    color: var(--cta);
}

footer a:hover {
    text-decoration: none;
}

@media (min-width: 350px) {
    :root {
        --fs-l: 3rem;
    }
}
@media (min-width: 750px) {
    :root {
        --fs-s: 20px;
        --fs-l: 4.75rem;
    }
    main {
        width: 650px;
        padding: 3rem;
        margin: 2rem;
    }
    form .input-container {
        grid-template-columns: repeat(3, minmax(auto, 125px));
    }
    .input-field .input {
        height: 4rem;
    }
    form .submit-btn {
        left: auto;
        margin-left: auto;
        bottom: -40px;
        width: 80px;
        height: 80px;
    }
    .submit-btn img {
        width: 40px;
        height: 40px;
    }
}