html {
  /* px means "pixels". The base font size is now 10 pixels high */
  font-size: 15px;
  /* Replace PLACEHOLDER with the font-family property value you got from Google Fonts */
  font-family: "Roboto", sans-serif;
}
h1 {
  font-size: 60px;
  text-align: center;
}

p,
li {
  font-size: 16px;
  line-height: 2;
  letter-spacing: 1px;
}
html {
  background-color: #00539f;
}
body {
  width: 600px;
  margin: 0 auto;
  background-color: #ff9500;
  padding: 0 20px 20px 20px;
  border: 5px solid black;
}
h1 {
  margin: 0;
  padding: 20px 0;
  color: #00539f;
  text-shadow: 3px 3px 1px black;
}
img {
  display: block;
  margin: 0 auto;
  max-width: 100%;
}
.done {
  color: darkseagreen;
  text-decoration: line-through solid black 2px;
}
button {
  display: block;
  margin: 40px auto;
  background: linear-gradient(90deg, #ff9500 0%, #00539f 100%);
  color: #fff;
  font-size: 1.2rem;
  font-weight: bold;
  padding: 15px 40px;
  border: none;
  border-radius: 30px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  cursor: pointer;
  transition:
    transform 0.2s,
    box-shadow 0.2s;
}
button:hover {
  transform: scale(1.05);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.25);
  background: linear-gradient(90deg, #00539f 0%, #ff9500 100%);
}