:root {
  --bg-color: #fafafa;
  --card-bg: #ffffff;
  --card-border: #dddddd;
  --card-shadow: rgba(0, 0, 0, 0.05);
  --text-color: #222222;
  --link-color: #0073e6;
  --link-hover: #005bb5;
  --code-bg: #f5f5f5;
  --button-bg: #0073e6;
  --button-text: #ffffff;
  --button-hover: #005bb5;
}

body {
  font-family: Arial, sans-serif;
  color: var(--text-color);
  background: var(--bg-color);
  max-width: 800px;
  margin: 2rem auto;
  padding: 3rem 1rem 1rem;
  line-height: 1.6;
  position: relative;
}

h1 {
  text-align: center;
  margin-bottom: 2rem;
}

/* Useful Tools list */
ul {
  list-style: none;
  padding: 0;
}
li {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 6px;
  padding: 1rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 2px 4px var(--card-shadow);
}
h4 a {
  text-decoration: none;
  color: var(--link-color);
}
h4 a:hover {
  text-decoration: underline;
  color: var(--link-hover);
}

/* Code blocks */
pre {
  background: var(--code-bg);
  padding: 0.5rem;
  border-radius: 4px;
  overflow-x: auto;
}
code {
  font-family: Consolas, monospace;
}
h5 {
  margin: 0.5rem 0 0.3rem;
}

/* Calculator-specific */
label {
  display: block;
  margin: 0.75rem 0;
}
input {
  width: 100%;
  padding: 0.6rem;
  font-size: 1rem;
  box-sizing: border-box;
  margin-top: 0.3rem;
}
button {
  margin-top: 1rem;
  padding: 0.7rem 1rem;
  font-size: 1rem;
  width: 100%;
  cursor: pointer;
  border: none;
  border-radius: 4px;
  background: var(--button-bg);
  color: var(--button-text);
}
button:hover {
  background: var(--button-hover);
}

/* Back button (top-right corner) */
.back-btn {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: var(--button-bg);
  color: var(--button-text);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  font-size: 0.9rem;
}
.back-btn:hover {
  background: var(--button-hover);
}

.result-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 6px;
  padding: 1rem;
  margin-top: 1rem;
  box-shadow: 0 2px 4px var(--card-shadow);
  font-size: 1.2rem;
  line-height: 1.8;
}
.result-card p {
  margin: 0.2rem 0 0.5rem;
}