:root {
  --bg-deep: #0a0e17;
  --bg-card: #121826;
  --bg-elevated: #1a2332;
  --bg-hover: #243044;
  --border: #2a3548;
  --border-glow: #3b82f6;
  --text-primary: #e8eef7;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent: #3b82f6;
  --accent-hover: #60a5fa;
  --accent-glow: rgba(59, 130, 246, 0.35);
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  --font: 'Inter', system-ui, -apple-system, sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', monospace;
  --transition: 0.22s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font);
  background: var(--bg-deep);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.5;
  overflow-x: hidden;
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(59, 130, 246, 0.12), transparent),
    radial-gradient(ellipse 60% 40% at 100% 100%, rgba(99, 102, 241, 0.08), transparent);
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 14, 23, 0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  padding: 0.85rem 1.25rem;
}

.header-inner {
  max-width: 1280px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  color: var(--text-primary);
}

.logo-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--accent), #6366f1);
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-size: 1.2rem;
  box-shadow: 0 0 20px var(--accent-glow);
}

.logo-text {
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: -0.02em;
}

.logo-sub {
  font-size: 0.7rem;
  color: var(--text-muted);
  font-weight: 500;
}

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.75rem;
  color: var(--success);
  background: rgba(34, 197, 94, 0.12);
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
  border: 1px solid rgba(34, 197, 94, 0.25);
}

.status-dot {
  width: 7px;
  height: 7px;
  background: var(--success);
  border-radius: 50%;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; box-shadow: 0 0 0 0 rgba(34, 197, 94, 0.5); }
  50% { opacity: 0.7; box-shadow: 0 0 0 6px rgba(34, 197, 94, 0); }
}

/* Search & Filter */
.controls {
  max-width: 1280px;
  margin: 1.5rem auto 0;
  padding: 0 1.25rem;
}

.search-wrap {
  position: relative;
  margin-bottom: 1rem;
}

.search-input {
  width: 100%;
  padding: 0.9rem 1.1rem 0.9rem 2.8rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-size: 0.95rem;
  transition: var(--transition);
  outline: none;
}

.search-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

.filter-tabs {
  display: flex;
  gap: 0.5rem;
  overflow-x: auto;
  padding-bottom: 0.5rem;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

.filter-tab {
  flex-shrink: 0;
  padding: 0.5rem 1rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.filter-tab:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.filter-tab.active {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
  box-shadow: 0 0 16px var(--accent-glow);
}

.result-count {
  margin-top: 0.85rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* Gallery */
.gallery {
  max-width: 1280px;
  margin: 1.25rem auto 3rem;
  padding: 0 1.25rem;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.1rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  animation: fadeInUp 0.4s ease both;
}

.card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 40%, rgba(59, 130, 246, 0.06));
  opacity: 0;
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.35), 0 0 0 1px var(--accent);
}

.card:hover::before {
  opacity: 1;
}

.card-icon {
  font-size: 1.8rem;
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  background: var(--bg-elevated);
  border-radius: 12px;
  border: 1px solid var(--border);
}

.card-title {
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}

.card-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  flex: 1;
}

.card-cat {
  font-size: 0.7rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  font-weight: 600;
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Modal / Calculator View */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  opacity: 0;
  visibility: hidden;
  transition: 0.25s ease;
}

.modal-overlay.open {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  width: 100%;
  max-width: 440px;
  max-height: 92vh;
  overflow-y: auto;
  box-shadow: var(--shadow);
  transform: scale(0.94) translateY(10px);
  transition: 0.25s cubic-bezier(0.34, 1.2, 0.64, 1);
}

.modal-overlay.open .modal {
  transform: scale(1) translateY(0);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg-card);
  z-index: 2;
}

.modal-title {
  font-weight: 600;
  font-size: 1.05rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.modal-close {
  width: 36px;
  height: 36px;
  border: none;
  background: var(--bg-elevated);
  color: var(--text-secondary);
  border-radius: 10px;
  cursor: pointer;
  font-size: 1.2rem;
  transition: var(--transition);
  display: grid;
  place-items: center;
}

.modal-close:hover {
  background: var(--danger);
  color: white;
}

.modal-body {
  padding: 1.25rem;
}

/* Calculator UI */
.calc-display {
  background: #0d1117;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.1rem;
  margin-bottom: 1rem;
  min-height: 72px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: flex-end;
  font-family: var(--mono);
  position: relative;
  overflow: hidden;
}

.calc-display::after {
  content: '';
  position: absolute;
  top: 8px;
  right: 12px;
  width: 8px;
  height: 8px;
  background: var(--success);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--success);
  animation: blink 3s infinite;
}

@keyframes blink {
  0%, 90%, 100% { opacity: 1; }
  95% { opacity: 0.3; }
}

.calc-expr {
  font-size: 0.85rem;
  color: var(--text-muted);
  min-height: 1.2em;
  word-break: break-all;
}

.calc-result {
  font-size: 1.7rem;
  font-weight: 600;
  color: var(--text-primary);
  word-break: break-all;
}

.calc-keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.55rem;
}

.calc-btn {
  aspect-ratio: 1.25;
  border: none;
  border-radius: 12px;
  font-size: 1.15rem;
  font-weight: 500;
  font-family: var(--font);
  cursor: pointer;
  transition: transform 0.08s, background 0.15s, box-shadow 0.15s;
  background: var(--bg-elevated);
  color: var(--text-primary);
  border: 1px solid var(--border);
  position: relative;
  overflow: hidden;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.calc-btn:active {
  transform: scale(0.94);
}

.calc-btn.op {
  background: rgba(59, 130, 246, 0.15);
  color: var(--accent-hover);
  border-color: rgba(59, 130, 246, 0.3);
}

.calc-btn.fn {
  background: rgba(99, 102, 241, 0.12);
  color: #a5b4fc;
  font-size: 0.85rem;
}

.calc-btn.eq {
  background: linear-gradient(135deg, var(--accent), #6366f1);
  color: white;
  border: none;
  grid-column: span 2;
  box-shadow: 0 4px 16px var(--accent-glow);
}

.calc-btn.clear {
  background: rgba(239, 68, 68, 0.15);
  color: #fca5a5;
  border-color: rgba(239, 68, 68, 0.3);
}

.calc-btn.zero {
  grid-column: span 2;
}

/* Form-based calculators */
.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-bottom: 0.35rem;
  font-weight: 500;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 0.7rem 0.9rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.95rem;
  font-family: var(--mono);
  outline: none;
  transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.btn-calc {
  width: 100%;
  padding: 0.85rem;
  background: linear-gradient(135deg, var(--accent), #6366f1);
  border: none;
  border-radius: var(--radius-sm);
  color: white;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: var(--transition);
  box-shadow: 0 4px 16px var(--accent-glow);
  margin-top: 0.5rem;
}

.btn-calc:hover {
  filter: brightness(1.1);
  transform: translateY(-1px);
}

.btn-calc:active {
  transform: scale(0.98);
}

.result-box {
  margin-top: 1.25rem;
  padding: 1rem;
  background: #0d1117;
  border: 1px solid var(--border);
  border-radius: 12px;
  font-family: var(--mono);
}

.result-box .label {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 0.25rem;
}

.result-box .value {
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--success);
}

.result-box .detail {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-top: 0.5rem;
  line-height: 1.6;
}

/* Empty state */
.empty {
  grid-column: 1 / -1;
  text-align: center;
  padding: 3rem 1rem;
  color: var(--text-muted);
}

.empty-icon {
  font-size: 3rem;
  margin-bottom: 0.75rem;
  opacity: 0.5;
}

/* Footer */
.footer {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--text-muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
}

.footer a {
  color: var(--accent);
  text-decoration: none;
}

/* Responsive */
@media (max-width: 600px) {
  .gallery {
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
  }
  .card {
    padding: 1rem;
  }
  .card-icon {
    width: 40px;
    height: 40px;
    font-size: 1.4rem;
  }
  .card-title {
    font-size: 0.92rem;
  }
  .card-desc {
    font-size: 0.75rem;
  }
  .modal {
    max-width: 100%;
    border-radius: 16px 16px 0 0;
    max-height: 95vh;
  }
  .calc-keys {
    gap: 0.4rem;
  }
  .calc-btn {
    font-size: 1.05rem;
  }
}

@media (max-width: 380px) {
  .gallery {
    grid-template-columns: 1fr;
  }
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}