/* ---------- GLOBAL RESET ---------- */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Poppins", sans-serif;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  align-items: center;
  color: #fff;
  text-align: center;
  overflow-x: hidden;
  background: linear-gradient(-45deg,#6a11cb,#2575fc,#ff512f,#dd2476);
  background-size: 400% 400%;
  animation: gradientBG 12s ease infinite;
}

@keyframes gradientBG {
  0% {background-position:0% 50%}
  50% {background-position:100% 50%}
  100% {background-position:0% 50%}
}

/* ---------- HEADER ---------- */
header {
  width: 100%;
  padding: 20px;
}

header h1 {
  font-size: 1.5rem;
  font-weight: 600;
}

/* ---------- TABS ---------- */
.tabs {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin: 10px 0 20px;
}

.tab-btn {
  padding: 8px 15px;
  border: none;
  cursor: pointer;
  border-radius: 6px;
  background: rgba(255,255,255,0.15);
  color: #fff;
  transition: 0.3s;
}

.tab-btn.active,
.tab-btn:hover {
  background: rgba(0,0,0,0.3);
  transform: scale(1.05);
}

/* ---------- CONTENT BOX ---------- */
.tab-content {
  display: none;
  width: 90%;
  max-width: 400px;
  backdrop-filter: blur(6px);
  background: rgba(255,255,255,0.1);
  padding: 20px;
  border-radius: 10px;
  margin-bottom: 80px;
  animation: pop 0.4s ease;
}

.tab-content.active { display: block; }

@keyframes pop {
  0%{transform: scale(.8); opacity:0}
  100%{transform: scale(1); opacity:1}
}

label {
  display: block;
  text-align: left;
  margin: 12px 0 4px;
}

input {
  width: 100%;
  padding: 8px;
  border: none;
  border-radius: 6px;
}

/* ---------- BUTTON ---------- */
.calc-btn {
  margin-top: 15px;
  width: 100%;
  padding: 10px;
  border: none;
  border-radius: 8px;
  background:#00000055;
  color:#fff;
  cursor:pointer;
  transition:.3s;
}

.calc-btn:hover {background:#00000099}

/* ---------- MODAL ---------- */
.modal {
  display: none;
  position: fixed;
  inset:0;
  background: rgba(0,0,0,0.6);
  justify-content:center;
  align-items:center;
}

.modal-content {
  background:#fff;
  color:#000;
  padding:25px;
  border-radius:10px;
  width:80%;
  max-width:320px;
  text-align:center;
  animation: pop .35s ease;
}

.close{
  float:right;
  font-size:22px;
  cursor:pointer;
}

/* ---------- FOOTER ---------- */
footer{
  position:fixed;
  bottom:0;
  width:100%;
  text-align:center;
  padding:10px 0;
  font-size: 0.8rem;
  background:rgba(0,0,0,0.35);
}