:root {
  --font-family: 'Poppins', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  --bg-color: #FDFCFC;
  --card-bg-color: #FFFFFF;
  --text-color: #4A4A4A;
  --heading-color: #333333;
  --pastel-green: #A8D8B9;
  --pastel-green-dark: #8EBF9F;
  --pastel-pink: #FADADD;
  --pale-pink: #FDEFF1;
  --danger-color: #E77D7D;
  --danger-color-dark: #d9534f;
  --border-color: #EAEAEA;
  --shadow-color: rgba(0, 0, 0, 0.07);
  --border-radius: 12px;
}
*, *::before, *::after {
    box-sizing: border-box;
}
html, body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-color);
  margin: 0;
  padding: 0;
  line-height: 1.6;
  overflow-x: hidden;
}
.container {
  width: 90%;
  max-width: 700px;
  margin: 0 auto;
  padding: 0 15px;
}
.site-header {
  padding: 15px 0;
  background-color: var(--pale-pink);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 10px var(--shadow-color);
  transition: transform 0.3s ease-in-out;
  will-change: transform;
  backface-visibility: hidden;
  perspective: 1000px;
}
.site-header.header-hidden {
    transform: translateY(-100%);
}
.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo h1 {
  margin: 0;
  font-size: 1.8rem;
  font-weight: 600;
  color: var(--heading-color);
}
a.logo { text-decoration: none; }
.main-nav ul {
    margin: 0;
    padding: 0;
    list-style: none;
    display: flex;
    gap: 15px;
}
.main-nav a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    padding: 8px 15px;
    border-radius: 8px;
    transition: all 0.3s ease;
}
.main-nav a:hover {
    background-color: var(--pastel-pink);
}
.main-nav a.active {
    background-color: var(--pastel-green);
    color: #fff;
}
.tool-section {
    display: none;
    padding: 30px 0;
}
.tool-section.active {
    display: block;
}
.card {
  background-color: var(--card-bg-color);
  border-radius: var(--border-radius);
  padding: 25px 30px;
  box-shadow: 0 4px 15px var(--shadow-color);
  margin-bottom: 30px;
  border: 1px solid var(--border-color);
}
h2 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--heading-color);
  margin-top: 0;
  margin-bottom: 20px;
  text-align: center;
}
.form-group { margin-bottom: 20px; }
label {
  display: block;
  font-weight: 500;
  margin-bottom: 8px;
  font-size: 0.95rem;
}
input, select {
  width: 100%;
  padding: 12px 15px;
  font-size: 1rem;
  font-family: var(--font-family);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background: #F9F9F9;
  color: var(--text-color);
  transition: all 0.3s ease;
}
input:focus, select:focus {
  outline: none;
  border-color: var(--pastel-green);
  box-shadow: 0 0 0 3px rgba(168, 216, 185, 0.3);
  background: #FFF;
}
.api-section small {
    font-size: 0.8rem;
    color: #999;
    display: block;
    margin-top: 8px;
    text-align: center;
}
.form-row {
    display: flex;
    gap: 20px;
}
.form-row .form-group {
    flex: 1;
}
button {
  padding: 12px 20px;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-family);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
button:disabled { opacity: 0.6; cursor: not-allowed; }
.button-primary { width: 100%; background-color: var(--pastel-green); color: var(--heading-color); }
.button-primary:hover:not(:disabled) { background-color: var(--pastel-green-dark); }
.button-secondary { background-color: #F0F0F0; color: var(--heading-color); }
.button-secondary:hover:not(:disabled) { background-color: #E0E0E0; }
#calculateBtn { width: 100%; }
.button-danger { background-color: var(--danger-color); color: white; }
.button-danger:hover:not(:disabled) { background-color: var(--danger-color-dark); }
.action-buttons { display: flex; justify-content: flex-end; gap: 15px; margin-top: 20px; flex-wrap: wrap; }
.action-buttons button { flex-grow: 0; }
.results-section h2 { text-align: left; border-bottom: 2px solid var(--pastel-pink); padding-bottom: 10px; }
.results-container .placeholder { color: #888; text-align: center; padding: 30px; background-color: #F9F9F9; border-radius: var(--border-radius); }
.query-item, .total-result { border: 1px solid var(--border-color); border-radius: var(--border-radius); margin-bottom: 15px; background: #FFF; overflow: hidden; }
.query-item summary, .total-result summary { display: flex; justify-content: space-between; align-items: center; padding: 15px 20px; cursor: pointer; list-style: none; font-weight: 500; }
.query-item summary::-webkit-details-marker, .total-result summary::-webkit-details-marker { display: none; }
.summary-title {
    display: flex;
    align-items: center;
    gap: 8px;
    overflow: hidden;
    flex-grow: 1;
}
.summary-title strong {
    font-size: 1.1rem;
    color: var(--heading-color);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.summary-amount {
    font-weight: 400;
    font-size: 0.9em;
    color: #777;
    flex-shrink: 0;
}
.total-result summary strong { font-size: 1.1rem; color: var(--heading-color); }
.summary-info { display: flex; align-items: center; gap: 15px; flex-shrink: 0; }
.summary-info .delete-btn { padding: 5px 10px; font-size: 0.8rem; }
.accordion-icon { transition: transform 0.3s ease; }
details[open] .accordion-icon { transform: rotate(180deg); }
.details-content { padding: 0 20px 20px; border-top: 1px solid var(--border-color); }
table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 12px 10px; border-bottom: 1px solid var(--border-color); }
th { font-weight: 600; font-size: 0.9rem; color: var(--heading-color); }
tr:last-child td { border-bottom: none; }
.bmi-result-container { text-align: center; margin-top: 20px; }
.bmi-result-container h3 { margin-bottom: 10px; }
.bmi-value { font-size: 3rem; font-weight: 700; color: var(--heading-color); margin: 0; }
.bmi-category { font-size: 1.2rem; font-weight: 500; margin: 5px 0 20px; }
.bmi-category.underweight { color: #3498db; }
.bmi-category.normal { color: #2ecc71; }
.bmi-category.overweight { color: #f39c12; }
.bmi-category.obese { color: #e74c3c; }
.bmi-gauge { position: relative; height: 20px; background: linear-gradient(to right, #3498db, #2ecc71, #f39c12, #e74c3c); border-radius: 10px; margin-bottom: 10px; }
.bmi-gauge-arrow { position: absolute; top: -5px; left: 50%; transform: translateX(-50%); width: 0; height: 0; border-left: 8px solid transparent; border-right: 8px solid transparent; border-top: 12px solid #333; transition: left 0.5s ease; }
.bmi-legend { display: flex; justify-content: space-between; font-size: 0.8rem; color: #777; }
.site-footer { margin-top: 40px; padding: 20px 0; font-size: 0.9rem; text-align: center; }
.footer-container { width: 90%; max-width: 400px; margin: 0 auto; padding-top: 20px; border-top: 1px solid var(--border-color); }
.modal-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background-color: rgba(0, 0, 0, 0.5); display: flex; justify-content: center; align-items: center; z-index: 1000; }
.modal-content { background-color: white; padding: 30px; border-radius: var(--border-radius); box-shadow: 0 5px 20px rgba(0,0,0,0.2); width: 90%; max-width: 400px; text-align: center; }
.modal-content p { margin: 0 0 25px; font-size: 1.1rem; }
.modal-actions { display: flex; justify-content: center; gap: 15px; }
.modal-actions button { width: 120px; }
.error-message { color: var(--danger-color); font-weight: 500; text-align: center; margin-top: 15px; min-height: 22px; }
.loader { border: 4px solid #f3f3f3; border-top: 4px solid var(--pastel-green); border-radius: 50%; width: 40px; height: 40px; animation: spin 1s linear infinite; margin: 20px auto; }
@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }
@media (max-width: 768px) {
    .header-container {
        flex-direction: column;
        gap: 15px;
    }
    .main-nav ul {
        justify-content: center;
        flex-wrap: wrap;
    }
}
@media (max-width: 600px) {
    .card { padding: 20px; }
    h2 { font-size: 1.3rem; }
    .form-row { flex-direction: column; gap: 0; }
    .action-buttons { flex-direction: column; align-items: stretch; }
    .action-buttons button { width: 100%; }
    .summary-title strong { font-size: 1rem; }
    .query-item summary, .total-result summary { padding: 12px 15px; }
    .summary-info { gap: 10px; }
    th, td { padding: 10px 8px; font-size: 0.9rem; }
    .bmi-value { font-size: 2.5rem; }
    .bmi-category { font-size: 1.1rem; }
    .bmi-legend { font-size: 0.7rem; }
}
@media (max-width: 400px) {
    .main-nav a { padding: 8px 10px; font-size: 0.9rem; }
    .logo h1 { font-size: 1.6rem; }
}