:root {
  /* Warm brown palette */
  --primary-color: #A1887F;
  --primary-hover: #8D6E63;
  --header-text: hsl(22, 35%, 30%);
  --container-bg: hsl(22, 35%, 30%);
  --page-background: #FDF6EC;
  --border-color: #D7CCC8;
  --white: #ffffff;
  --black: #000000;
}

/* Global Reset and System Font */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  height: 100%;
}
body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: linear-gradient(180deg, hsl(47, 48%, 90%) 0%, hsl(51, 61%, 79%) 100%);
  background-repeat: no-repeat;
  background-size: cover;
  background-attachment: fixed;
  
  color: var(--header-text);
  line-height: 1.6;
  padding: 20px;
  height: 100%;
  display: flex;
  flex-direction: column;
}
main {
  flex: 1;
  padding: 20px;
}

/* Header and Tabs */
.header {
  text-align: center;
  margin-bottom: 20px;
}

.header h1 {
  font-size: 3rem;
  font-weight: 700;
  color: var(--header-text);
  margin-bottom: 20px;
  font-family: Marker Felt, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  text-shadow: 1px 5px 22px hsl(18, 23%, 63%);
  letter-spacing: .1rem;
}

.tabs {
  display: inline-flex;
  border-bottom: 1px solid hsl(18, 18%, 74%);
}

.tablink {
  padding: 12px 20px;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.25rem;
  transition: border-color 0.3s, color 0.3s;
  color: var(--header-text);
  border-bottom: 2px solid transparent;
}

.tablink:hover {
  border-color: var(--primary-hover);
}

.tablink.active {
  border-color: var(--primary-color);
  font-weight: 700;
  color: var(--header-text);
}

/* Conversion Container */
.container {
  background: var(--container-bg);
  color: var(--white);
  border-radius: 10px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
  width: 100%;
  max-width: 800px;
  padding: 60px;
  margin: 0 auto 40px;
  color: #ddd8d0;
  background: linear-gradient(180deg, rgba(196,174,155,0.28) 0%, rgba(98,62,46,0.74) 100%), url(images/leather.png);
  background-size: 140px;
  box-shadow: 0 3px 7px 0 rgba(104,76,64,0.61), inset 0 -1px 4px 0 #392F29, inset 0 2px 1px 0 rgba(224,195,185,0.75);
}

/* Converter Layout */
.converter {
  display: flex;
  flex-direction: column;
  gap: 30px;
}

.input-group {
  display: flex;
  gap: 20px;
  align-items: center;
  flex-wrap: wrap;
}

input[type="number"] {
  flex: 1;
  padding: 20px 25px;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  font-size: 1.5rem;
  transition: border-color 0.2s;
  background: var(--white);
  color: var(--black);
  min-width: 150px;
}

input[type="number"]:focus {
  border-color: var(--primary-color);
  outline: none;
}

select {
  padding: 20px 25px;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  background: var(--white);
  font-size: 1.5rem;
  transition: border-color 0.2s;
  color: var(--black);
  min-width: 150px;
}

select:focus {
  border-color: var(--primary-color);
  outline: none;
}

/* NoteStack Link */
.notestack-link {
  text-align: center;
  margin: 20px auto;
  font-size: 0.9rem;
}

.notestack-link a {
  display: inline-flex;
  align-items: center;
  background: var(--white);
  color: var(--container-bg);
  border: 1px solid var(--container-bg);
  padding: 8px 12px;
  border-radius: 4px;
  text-decoration: none;
  transition: background 0.2s;
}

.notestack-link a:hover {
  background-color: hsl(41, 59%, 88%);
}

.notestack-icon {
  width: 20px;
  height: 20px;
  margin-right: 8px;
}

/* Spinner styling */
.spinner {
  text-align: center;
  margin-bottom: 20px;
  font-size: 1.2rem;
  color: #FFF;
}

.spinner:before {
  content: "";
  display: inline-block;
  vertical-align: middle;
  width: 24px;
  height: 24px;
  border: 3px solid var(--border-color);
  border-top-color: var(--primary-color);
  border-radius: 50%;
  animation: spinner 0.6s linear infinite;
  margin-right: 8px;
}

@keyframes spinner {
  to { transform: rotate(360deg); }
}

footer {
	text-align: center;
	padding-bottom: 20px;
}
footer a {
	margin-right: 20px;
	color: #8c6b5d;
	text-decoration: none;
}
footer a:hover {
	text-decoration: underline;
}

#about p{
	margin-bottom: 20px;
}
#about p {
  font-size: clamp(20px, 2vmin, 40px);
}
main#about {
	width: 50%;
	margin: 0 auto;
}
/* Hide non-active tab content */
.tabcontent {
  display: none;
}

.tabcontent.active {
  display: block;
}

/* Responsive adjustments for iPhones and small screens */
@media only screen and (max-width: 480px) {
  .header h1 {
    font-size: 2.5rem;
  }
  .tablink {
    font-size: 1rem;
    padding: 10px 12px;
  }
  .container {
    padding: 30px 20px;
  }
  input[type="number"], select {
    font-size: 1.25rem;
    padding: 15px 20px;
  }
 
}
@media only screen and (max-width: 768px) {
	 main#about {
	width: 90%;
  }
}