:root {
  --clr-primary-cyan: hsl(172, 67%, 45%);

  --clr-very-dark-cyan: hsl(183, 100%, 15%);
  --clr-dark-grayish-cyan: hsl(186, 14%, 43%);
  --clr-grayish-cyan: hsl(184, 14%, 56%);
  --clr-light-grayish-cyan: hsl(185, 41%, 84%);
  --clr-very-light-grayish-cyan: hsl(189, 41%, 97%);
  --clr-white: hsl(0, 0%, 100%);
}

input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

* {
  box-sizing: border-box;
  font-family: 'Space Mono', monospace;
}

body, 
h1, 
h2, 
p, 
input {
  margin: 0;
  padding: 0;
}

body {
  position: relative;

  display: flex;
  flex-direction: column;
  justify-content: center;

  min-height: 100vh;
  font-size: 24px;
  background-color: var(--clr-light-grayish-cyan);
}

h1 {
  text-align: center;
  letter-spacing: 10px;
  font-size: 1em;
  color: var(--clr-dark-grayish-cyan);
}

.app-container {
  display: grid;
  grid-template-columns: 50% 50%;

  margin-top: 4em;
  margin-inline: auto;
  padding: 1em;

  max-width: 920px;
  height: 480px;

  border-radius: 1em;
  background-color: var(--clr-white);
}


/* left side of the app */

.bill-settings {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 1em 2em 1em 1em;
}

.bill-settings h2 {
  font-size: 0.75em;
  color: var(--clr-dark-grayish-cyan);
}

.number-input {
  margin-top: 5px;
  padding: 5px 10px;
  width: 100%;

  font-size: 1em;
  text-align: right;

  border: none;
  border-radius: 5px;
  background-color: var(--clr-very-light-grayish-cyan);
  background-repeat: no-repeat;
  background-position: 15px center;
}

.number-input::placeholder {
  color: var(--clr-grayish-cyan);
}

.number-input:hover {
  cursor: pointer;
  outline: 2px solid var(--clr-primary-cyan);
}

.number-input:focus {
  outline: 2px solid var(--clr-primary-cyan);
}

.number-input.bill {
  background-image: url(./images/icon-dollar.svg);
}

.tip-buttons-container {
  margin-top: 15px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5em;
}

.tip-button {
  padding: 5px 10px;
  width: 100%;

  font-size: 1em;
  color: var(--clr-very-light-grayish-cyan);

  border: none;
  border-radius: 5px;
  background-color: var(--clr-very-dark-cyan);
}

.tip-button:hover {
  cursor: pointer;
  color: var(--clr-very-dark-cyan);
  background-color: var(--clr-primary-cyan);
}

.tip-button.active {
  color: var(--clr-very-dark-cyan);
  background-color: var(--clr-primary-cyan);
}

.tip-button.custom {
  text-align: right;
  color: var(--clr-dark-grayish-cyan);
  background-color: var(--clr-very-light-grayish-cyan);
}

.tip-button.custom::placeholder {
  color: var(--clr-dark-grayish-cyan);
}

.tip-button.custom:hover {
  outline: 2px solid var(--clr-primary-cyan);
}

.tip-button.custom:focus {
  outline: 2px solid var(--clr-primary-cyan);
}

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

.people-amount-message {
  visibility: hidden;
  font-size: 0.75em;
  color: red;
}

.number-input.people {
  background-image: url(./images/icon-person.svg);
}


/* right side of the app */

.total-information-container {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  
  padding: 2em 1.75em;
  
  border-radius: 0.75em;
  background-color: var(--clr-very-dark-cyan);
}

.tip-amount-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.tip-amount-text-container h2 {
  font-size: 0.65em;
  color: var(--clr-white);
}

.tip-amount-text-container p {
  font-size: 0.6em;
  color: var(--clr-grayish-cyan);
}

.total-amount {
  font-size: 1.75em;
  color: var(--clr-primary-cyan);
}

.reset-button {
  padding: 10px;
  width: 100%;

  font-size: 0.75em;

  background-color: var(--clr-primary-cyan);
  border: none;
  border-radius: 5px;

  opacity: 0.2;
}

.reset-button.available {
  opacity: 1.0;
}

.reset-button.available:hover {
  cursor: pointer;
  background-color: var(--clr-light-grayish-cyan);
}

footer {
  position: absolute;
  bottom: 0;
  width: 100%;
  text-align: center;
  font-size: 14px;
}

footer a {
  color: inherit;
}

/* mobile design */

@media (max-width: 700px) {
  body {
    padding-block: 2em 4em;
  }
  .app-container {
    margin-top: 1.5em;
    padding: 1em;
    grid-template-columns: 1fr;
    max-width: 370px;
    height: auto;
  }

  .bill-settings {
    padding: 0;
    gap: 1em;
  }

  .bill-settings h2 {
    font-size: 0.65em;
  }

  .tip-buttons-container {
    grid-template-columns: 1fr 1fr;
  }

  .people-amount-message {
    font-size: 0.65em;
  }

  .total-information-container {
    margin-top: 1.5em;
    padding: 1.5em 1em 1em;
  }

  .tip-amount-container {
    margin-bottom: 1em;
  }

  .tip-amount-text-container h2 {
    font-size: 0.55em;
  }

  .tip-amount-text-container p {
    font-size: 0.5em;
  }

  .total-amount {
    font-size: 1.25em;
  }
}