app.css

/* makes sizing simpler */

*,
*::before,
*::after {
    box-sizing: border-box;
}

/* remove default spacing */
/* force styling of type through styling, rather than elements */

* {
    margin: 0;
    padding: 0;
    font: inherit;
}

/* dark mode user-agent-styles */

html {
    color-scheme: dark light;
}

/* min body height */

body {
    min-height: 100vh;
    background-color: hsl(204, 43%, 93%);
}

/* responsive images/videos */
img,
picture,
svg,
video {
    display: block;
    max-width: 100%;
}


/* my code */

.container {
    height: auto;
    margin: 18px 18px;
    font-family: karla, sans-serif;
}


.cell {
    display: flex;
    flex-direction: column;
    padding: 0 30px 0 20px;
    font-size: 16px;
}


.first-section {
    background-color: white;
    height: 260px;
    border-radius: 8px 8px 0 0;
}

.mid-section {
    background-color: hsl(179, 62%, 43%);
    height: 240px;
}

.last-section {
    background-color: hsl(179, 62%, 48%);
    height: 260px;
    padding-right: 6em;
    border-radius: 0 0 8px 8px;
}

.first-section h1 {
    font-size: 22px;
    font-weight: 700;
    padding: 20px 0;
    color: hsl(179, 62%, 43%);
}

.first-section p:first-of-type {
    color: hsl(71, 73%, 54%);
    font-weight: 600;
    padding-bottom: 20px;
}

.first-section p:last-child {
    color: hsl(218, 22%, 67%);
    line-height: 1.499;
}

.mid-section p:first-child {
    font-size: 19px;
    font-weight: 600;
    color: white;
    padding: 20px 0;
}

#price {
    font-size: 1.7em;
    color: white;
    font-weight: 600;
    padding-right: 10px;
}

.mid-section p:nth-child(2) {
    padding-bottom: 10px;
    color: hsl(220, 21%, 86%);
}

#sub-time {
    display: inline-block;
    transform: translateY(-3px);
}

.mid-section p:last-of-type {
    color: rgb(235, 238, 241);
    padding-bottom: 2em;
}

/* Sign-up button */

button {
    padding: 14px;
    border-radius: 7px;
    border: none;
    color: white;
    max-width: 375px;
    background-color: hsl(71, 73%, 54%);
}

.last-section p:first-child {
    font-size: 1.2em;
    color: white;
    padding: 22px 0;
    font-weight: 600;
}

.last-section p:last-child {
    line-height: 1.5em;
    color: rgb(228, 228, 228);
}


/* Screen size more than 575px */

@media (min-width:575px) {

    body {
        display: flex;
        justify-content: center;
        align-items: center;
    }

    .container {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        height: 68vh;
        max-width: 710px;
    }

    .first-section {
        grid-column: span 2;
        justify-content: center;
        height: 100%;
    }

    .mid-section {
        justify-content: center;
        border-radius: 0 0 0 8px;
        height: 100%;
    }

    .last-section {
        justify-content: center;
        border-radius: 0 0 8px 0;
        height: 100%;
    }

    button {
        margin-right: 30px;
    }
}