/* Base */
body {
  font-family: sans-serif;
  margin: 0; padding: 0;
  background: #f4f4f4;
  color: #333333;
}
header {
  background: linear-gradient(to bottom, #000000, #222222);
  color: #fff;
  padding: 1.5rem 1rem;
  text-align: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}
.logo {
  max-height: 60px;
  display: block;
  margin: 0 auto .5rem;
  background-color: #fff;
  padding: 8px;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(255,255,255,0.3);
  border: 2px solid #ff6600;
}
h1 {
  margin: 0;
  font-size: 1.25rem;
}

/* Unit Toggle */
.unit-toggle-container {
  margin-top: .75rem;
}
.unit-toggle-button {
  background: #ff6600;
  color: #fff;
  border: none;
  padding: .5rem 1rem;
  font-size: 1rem;
  border-radius: .25rem;
  cursor: pointer;
  transition: background .2s;
}
.unit-toggle-button:hover {
  background: #e65c00;
}
.toggle-icon {
  margin-left: .5rem;
}

/* Tabs */
.tabs {
  display: flex;
  background: #eaeaea;
}
.tabs button {
  flex: 1;
  padding: .75rem;
  border: none;
  background: #ddd;
  cursor: pointer;
  font-size: 1rem;
}
.tabs button.active {
  background: #fff;
  font-weight: bold;
  border-bottom: 4px solid #ff6600;
  color: #ff6600;
}

/* Sections */
.section {
  display: none;
}
.section.active {
  display: block;
}

/* Calculator Box */
.calculator {
  max-width: 360px;
  margin: 2rem auto;
  background: #fff;
  padding: 1.5rem;
  border-radius: .5rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
.calculator label {
  display: block;
  margin-bottom: 1rem;
  font-weight: 500;
}
.calculator input {
  width: 100%;
  padding: .5rem;
  margin-top: .25rem;
  border: 1px solid #ccc;
  border-radius: .25rem;
  font-size: 1rem;
}
.calculator button {
  width: 100%;
  padding: .75rem;
  background: #ff6600;
  border: none;
  color: #fff;
  font-size: 1rem;
  border-radius: .25rem;
  cursor: pointer;
  margin-top: 1rem;
}
.calculator button:hover {
  background: #e65c00;
}

/* Results with fade‑in */
.results {
  margin-top: 1.5rem;
  background: #fff9e6;
  padding: 1rem;
  border-radius: .25rem;
  border-left: 4px solid #ff6600;
  opacity: 0;
  transition: opacity .3s ease-in-out;
}
.results.visible {
  opacity: 1;
}
.hidden {
  display: none;
}