*, 
*::before, 
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }

:root {
    --Strong-cyan: hsl(172, 67%, 45%);
    --Very-dark-cyan: hsl(183, 100%, 15%);
    --Dark-grayish-cyan: hsl(186, 14%, 43%);
    --Grayish-cyan: hsl(184, 14%, 56%);
    --Light-grayish-cyan: hsl(185, 41%, 84%);
    --Very-light-grayish-cyan: hsl(189, 41%, 97%);
    --White: hsl(0, 0%, 100%);
}

html {
    scroll-behavior: smooth;
}

html, body {
    height: 100%;
}

img, picture, video, canvas, svg {
    display: block;
    max-width: 100%;
}

input, button, textarea, select {
    font: inherit;
    font-family: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
    overflow-wrap: break-word;
}

ul {
    list-style: none;
}

a {
    text-decoration: none;
}

body {
    font-family: 'Space Mono', monospace;
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    background-color: var(--Light-grayish-cyan);
    display: grid;
    place-items: center;
    min-height: 100%;
}

.sr-only {
    position: absolute ;
    left: -10000px;
    width: 1px;
    height: 1px;
    top: auto;
    overflow: hidden;
  }

main {
    margin-top: auto;
}

.wrapper {
    margin-inline: auto;
    margin-bottom: 3rem;
}

.logo {
    margin-inline: auto;
    margin-block: 3.5rem;
}

.calculator {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    background-color: var(--White);
    padding: 2rem;
    border-radius: 25px;
}

.bill-section, .people-section {
    position: relative;
}

.bill-section::before, .people-section::before {
    content: '';
    display: inline-block;
    background-size: contain;
    position: absolute;
    bottom: .85rem;
    left: 1rem;
}

.bill-section::before {
    background: url("./images/icon-dollar.svg") no-repeat center;
    width: 20px;
    height: 20px;
}

.people-section::before {
    background: url("./images/icon-person.svg") no-repeat center; 
    width: 18px;
    height: 18px;
}

.select-section {
    margin-block: 2rem;
}

.tips {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(115px,1fr));
    gap: 1rem;
}

.tips > * {
    width: 100%;
    padding: .4rem;
    border-radius: 6px;
}

.tip {
    background-color: var(--Very-dark-cyan);
    color: var(--White);
    border: 1px solid var(--Very-dark-cyan);
}

label {
    font-size: 1rem;
    color: var(--Dark-grayish-cyan);
}

input {
    width: 100%;
    text-align: end;
    padding: .3rem 1rem;
    background-color: hsla(180, 11%, 81%, 0.349);
    color: var(--Very-dark-cyan);
    border: 1px solid transparent;
    border-radius: 6px;
}

input::placeholder {
    color: var(--Grayish-cyan);
}

.error {
    opacity: 0;
    position: absolute;
    top: .5rem;
    right: 0;
    font-size: 1rem;
    color: red;
}

#custom::placeholder {
    text-align: center;
    color:var(--Dark-grayish-cyan);
}

.right {
    background-color: var(--Very-dark-cyan);
    padding: 1.5rem;
    border-radius: 15px;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.container {
    display: flex;
    justify-content: space-between;
}

.info > span {
    font-size: 1rem;
    color: var(--White);
}

.info > p {
    font-size: .85rem;
    color: var(--Dark-grayish-cyan);
}

.sum {
    color: var(--Strong-cyan);
    font-size: 2.1rem;
    place-self: end;
}

.reset {
    width: 100%;
    outline: none;
    border: none;
    border-radius: 6px;
    background-color: var(--Strong-cyan);
    color: var(--Very-dark-cyan);
    padding: .35rem;
    text-transform: uppercase;
    opacity: .3;
}

.tip.active {
    background-color: var(--Strong-cyan);
    border-color: var(--Strong-cyan);
    color: var(--Very-dark-cyan);
}

footer {
    margin-top: auto;
    text-align: center;
}

@media (pointer:fine) and (hover:hover) {
    .reset:is(:hover,:focus) {
        background-color: hsl(167, 35%, 74%);
        transition: .3s ease-in-out;
        cursor: pointer;
    }

    .tip:is(:hover,:focus){
        background-color: hsl(167, 35%, 74%);
        border-color: hsl(167, 35%, 74%);
        outline: none;
        color: var(--Very-dark-cyan);
        transition: .3s ease-in-out;
        cursor: pointer;
    }

    .tip.active:is(:hover,:focus) {
        background-color: var(--Strong-cyan);
        border-color: var(--Strong-cyan);
        color: var(--Very-dark-cyan);
        transition: .3s ease-in-out;
    }

    input:is(:hover,:focus) {
        box-shadow: 1px 1px 10px hsl(167, 35%, 74%);
        border: 1px solid hsl(167, 35%, 74%);
        outline: none;
        cursor: pointer;
    }

}

@media (min-width: 900px) {
    .wrapper {
        margin-bottom: 0;
    }

    .logo {
        margin-top: 0;
        margin-bottom: 5rem;
    }

    .calculator {
        flex-direction: row;
    }

    .calculator > * {
        flex-basis: 50%;
    }

    .left {
        margin: .8rem;
    }

    .right {
        padding: 2.5rem 2rem;
    }

    .sum {
        font-size: 2.5rem;
    }

    .reset {
        margin-top: auto;
    }
}