index.css

@import url('../../fonts/Montserrat/Montserrat.css');

*,
*::after,
*::before {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Montserrat', sans-serif;
}

body {
  background-color: #f2f3f4;
}

#container {
  --arrow-size: 10px;
  --arrow-color: #00958c;
  display: grid;
  row-gap: 1rem;
  margin-top: 1rem;
  justify-content: center;
  justify-items: center;
}

#title {
  font-weight: 800;
  font-size: 2.3rem;
  text-align: center;
  color: #00958c;
}

img {
  --img-size: 7rem;
  height: var(--img-size);
  width: var(--img-size);
  transition: transform 1s;
}

#image_container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.7rem;
  padding: 0.5rem;
}

.arrow {
  height: 0;
  width: 0;
  background-color: #f2f3f4;
  justify-self: center;
  cursor: pointer;
  border: none;
  align-self: center;
}

.arrow:focus {
  outline: 2px solid #00958c;
}

.images {
  display: grid;
  grid-template-rows: 0.2fr 1fr 0.2fr;
  grid-template-columns: 0.2fr 1fr 0.2fr;
  grid-template-areas:
    'up up up'
    'left photo right'
    'down down down';
}

.up_arrow {
  border-left: var(--arrow-size) solid transparent;
  border-right: var(--arrow-size) solid transparent;
  border-bottom: var(--arrow-size) solid var(--arrow-color);
  grid-area: up;
}

.down_arrow {
  border-top: var(--arrow-size) solid var(--arrow-color);
  border-left: var(--arrow-size) solid transparent;
  border-right: var(--arrow-size) solid transparent;
  grid-area: down;
}

.left_arrow {
  border-top: var(--arrow-size) solid transparent;
  border-bottom: var(--arrow-size) solid transparent;
  border-right: var(--arrow-size) solid var(--arrow-color);
  grid-area: left;
}

.right_arrow {
  border-top: var(--arrow-size) solid transparent;
  border-bottom: var(--arrow-size) solid transparent;
  border-left: var(--arrow-size) solid var(--arrow-color);
  grid-area: right;
}

#input_container {
  display: grid;
  width: fit-content;
}

.error {
  color: red;
  font-weight: 700;
  text-align: center;
  font-size: 0.7rem;
  margin-top: 0.1rem;
  margin-bottom: 0.5rem;
  opacity: 0;
}

#image_url {
  font-size: 1.2rem;
  text-align: center;
  border-style: solid;
  border-color: #00958c;
  padding: 0.2em 0.5em;
  border-radius: 5px;
  color: darkslategray;
  font-weight: 500;
  caret-color: #00958c;
}

#image_url:focus {
  outline: none;
  border-color: #00958c;
  background-color: white;
  box-shadow: 0 0 0 2px #00958c;
}

#load_url {
  border: none;
  background-color: #00958c;
  color: white;
  font-weight: 700;
  font-size: 1.2rem;
  width: fit-content;
  justify-self: center;
  padding: 0.5em 1em;
  border-radius: 5px;
  cursor: pointer;
}

#load_url:focus {
  outline: none;
  box-shadow: 0 0 7px 2px #00958c;
}