* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  color: #111;
  background: #fff;
}

/* ====== Layout ====== */
header, main, footer {
  display: block;
}

body > header,
body > main,
body > footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 20px;
}

body > header {
  padding-bottom: 8px;
}

body > main {
  padding-top: 8px;
}

/* ====== Typography ====== */
h1 {
  margin: 0 0 12px 0;
  font-size: 34px;
  font-weight: 700;
  text-align: center;
}

p {
  margin: 0 0 12px 0;
}

/* ====== Calculator form styling ====== */
main section {
  margin-top: 12px;
}

label {
  display: block;
  margin-top: 14px;
  margin-bottom: 6px;
  font-weight: 700;
}

input[type="number"],
input[type="text"] {
  display: block;
  width: 100%;
  padding: 10px 12px;
  font-size: 16px;
  border: 1px solid #cfcfcf;
  border-radius: 6px;