:root {
  --color-primary: #4f46e5;
  --color-primary-dark: #4338ca;
  --color-primary-light: #eef2ff;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-border: #e2e8f0;
  --color-success: #16a34a;
  --color-warning: #f59e0b;
  --color-danger: #dc2626;

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;

  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 16px 40px rgba(15, 23, 42, 0.12);

  --font-main: "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  --font-ar: "Segoe UI", "Tahoma", "Arial", sans-serif;

  --transition: 0.2s ease;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-main);
  line-height: 1.5;
}

html[lang="ar"] body {
  font-family: var(--font-ar);
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

a { text-decoration: none; color: inherit; }

/* Header */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  gap: 16px;
}

.logo {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

.main-nav {
  flex: 1;
  display: flex;
  gap: 20px;
  font-weight: 600;
  color: var(--color-text-muted);
}

.main-nav a:hover { color: var(--color-primary); }

.lang-toggle {
  background: var(--color-primary-light);
  color: var(--color-primary);
  border: none;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
  font-size: 0.95rem;
}

.lang-toggle:hover {
  background: var(--color-primary);
  color: #fff;
  transform: translateY(-1px);
}

/* Hero */
.hero {
  text-align: center;
  padding: 64px 24px 32px;
}

.hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.hero-sub {
  color: var(--color-text-muted);
  font-size: 1.15rem;
}

/* Tool grid */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
  padding: 24px 0 80px;
}

.tool-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.tool-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

.tool-icon { font-size: 2.2rem; margin-bottom: 8px; }

.tool-card h2 { font-size: 1.25rem; font-weight: 700; margin: 0; }

.tool-card p { color: var(--color-text-muted); margin: 0; font-size: 0.95rem; }

/* Tool pages */
.tool-page {
  padding: 48px 24px 80px;
  max-width: 640px;
}

.tool-page h1 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 8px;
}

.tool-desc {
  color: var(--color-text-muted);
  margin-bottom: 28px;
}

.calc-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
}

.form-row {
  margin-bottom: 18px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-row label {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--color-text);
}

.form-row input {
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--color-border);
  font-size: 1rem;
  font-family: inherit;
  background: var(--color-bg);
  color: var(--color-text);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.form-row input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

.btn-primary {
  width: 100%;
  padding: 14px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
  margin-top: 8px;
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-1px);
}

.btn-primary:active { transform: translateY(0); }

/* Unit switch (BMI + Percentage mode selector) */
.unit-switch {
  display: flex;
  flex-wrap: wrap;
  background: var(--color-bg);
  border-radius: var(--radius-sm);
  padding: 4px;
  margin-bottom: 22px;
  border: 1px solid var(--color-border);
}

.unit-btn {
  flex: 1;
  padding: 10px;
  border: none;
  background: transparent;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
  color: var(--color-text-muted);
  transition: all var(--transition);
  font-family: inherit;
  font-size: 0.9rem;
}

.unit-btn.active {
  background: var(--color-surface);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

/* Percentage mode buttons — same pattern as .unit-btn, sized for 3 short labels */
.pct-mode-btn {
  flex: 1;
  min-width: 100px;
  padding: 10px 6px;
  border: none;
  background: transparent;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
  color: var(--color-text-muted);
  transition: all var(--transition);
  font-family: inherit;
  font-size: 0.82rem;
}

.pct-mode-btn.active {
  background: var(--color-surface);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

/* Results */
.result-box {
  margin-top: 24px;
  padding: 24px;
  background: var(--color-primary-light);
  border-radius: var(--radius-md);
  text-align: center;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.result-main {
  display: flex;
  justify-content: center;
  align-items: baseline;
  gap: 8px;
  flex-wrap: wrap;
  font-size: 1.1rem;
  color: var(--color-primary-dark);
  font-weight: 700;
  margin-bottom: 12px;
}

.result-number {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-primary);
}

.result-details {
  list-style: none;
  padding: 0;
  margin: 16px 0 0;
  text-align: start;
  border-top: 1px solid rgba(79, 70, 229, 0.15);
  padding-top: 16px;
}

.result-details li {
  display: flex;
  justify-content: space-between;
  padding: 6px 0;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

.result-details li strong { color: var(--color-text); }

.error-box {
  margin-top: 20px;
  padding: 14px 18px;
  background: #fef2f2;
  color: var(--color-danger);
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.92rem;
}

.hidden { display: none !important; }

/* BMI scale */
.bmi-category-label {
  font-weight: 700;
  font-size: 1.1rem;
  margin: 0 0 16px;
}

.bmi-scale-bar {
  height: 12px;
  border-radius: 6px;
  background: linear-gradient(to right, #60a5fa 0% 25%, #22c55e 25% 50%, #f59e0b 50% 75%, #ef4444 75% 100%);
  position: relative;
  margin-bottom: 8px;
}

.bmi-marker {
  position: absolute;
  top: -6px;
  width: 4px;
  height: 24px;
  background: #1e293b;
  border-radius: 2px;
  transform: translateX(-50%);
  transition: left 0.4s ease;
}

.bmi-scale-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

/* Footer */
.site-footer {
  padding: 32px 24px;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  border-top: 1px solid var(--color-border);
}

/* RTL adjustments */
html[dir="rtl"] .result-details {
  text-align: right;
}

html[dir="rtl"] .bmi-marker {
  transform: translateX(50%);
}

/* Responsive */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.9rem; }
  .header-inner { flex-wrap: wrap; }
  .main-nav { order: 3; width: 100%; }
  .calc-card { padding: 22px; }
}