:root {
  --bg: #0b0f17;
  --panel: rgba(255, 255, 255, 0.04);
  --panel-2: rgba(255, 255, 255, 0.06);
  --border: rgba(255, 255, 255, 0.1);
  --text: rgba(255, 255, 255, 0.92);
  --muted: rgba(255, 255, 255, 0.68);
  --muted-2: rgba(255, 255, 255, 0.52);
  --accent: #6ee7ff;
  --accent-2: #a78bfa;
  --danger: #fb7185;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.45);
  --radius: 14px;
  --radius-sm: 10px;
  --font: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji",
    "Segoe UI Emoji";
  --font-heading: 'Exo 2', ui-sans-serif, system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
  --focus-ring: 0 0 0 3px rgba(110, 231, 255, 0.45);
  --focus-border: rgba(110, 231, 255, 0.6);
  --page-bg: radial-gradient(1000px 800px at 20% 10%, rgba(167, 139, 250, 0.18), rgba(0, 0, 0, 0)) ,
    radial-gradient(900px 700px at 70% 40%, rgba(110, 231, 255, 0.12), rgba(0, 0, 0, 0)) ,
    linear-gradient(180deg, #070a10 0%, var(--bg) 70%);
}

html {
  color-scheme: dark;
}

body[data-theme="dark"][data-contrast="high"] {
  --panel: rgba(255, 255, 255, 0.06);
  --panel-2: rgba(255, 255, 255, 0.085);
  --border: rgba(255, 255, 255, 0.18);
  --text: rgba(255, 255, 255, 0.97);
  --muted: rgba(255, 255, 255, 0.78);
  --muted-2: rgba(255, 255, 255, 0.62);
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.55);
}

@media (prefers-color-scheme: dark) {
  body:not([data-theme])[data-contrast="high"] {
    --panel: rgba(255, 255, 255, 0.06);
    --panel-2: rgba(255, 255, 255, 0.085);
    --border: rgba(255, 255, 255, 0.18);
    --text: rgba(255, 255, 255, 0.97);
    --muted: rgba(255, 255, 255, 0.78);
    --muted-2: rgba(255, 255, 255, 0.62);
    --shadow: 0 18px 50px rgba(0, 0, 0, 0.55);
  }
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f7fb;
    --panel: rgba(0, 0, 0, 0.04);
    --panel-2: rgba(0, 0, 0, 0.06);
    --border: rgba(0, 0, 0, 0.12);
    --text: rgba(0, 0, 0, 0.92);
    --muted: rgba(0, 0, 0, 0.64);
    --muted-2: rgba(0, 0, 0, 0.5);
    --shadow: 0 18px 50px rgba(0, 0, 0, 0.16);
    --page-bg: radial-gradient(1000px 800px at 20% 10%, rgba(167, 139, 250, 0.14), rgba(0, 0, 0, 0)) ,
      radial-gradient(900px 700px at 70% 40%, rgba(110, 231, 255, 0.12), rgba(0, 0, 0, 0)) ,
      linear-gradient(180deg, #ffffff 0%, var(--bg) 70%);
  }

  html {
    color-scheme: light;
  }
}

body[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0b0f17;
  --panel: rgba(255, 255, 255, 0.04);
  --panel-2: rgba(255, 255, 255, 0.06);
  --border: rgba(255, 255, 255, 0.1);
  --text: rgba(255, 255, 255, 0.92);
  --muted: rgba(255, 255, 255, 0.68);
  --muted-2: rgba(255, 255, 255, 0.52);
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.45);
  --page-bg: radial-gradient(1000px 800px at 20% 10%, rgba(167, 139, 250, 0.18), rgba(0, 0, 0, 0)) ,
    radial-gradient(900px 700px at 70% 40%, rgba(110, 231, 255, 0.12), rgba(0, 0, 0, 0)) ,
    linear-gradient(180deg, #070a10 0%, var(--bg) 70%);
}

body[data-theme="light"] {
  color-scheme: light;
  --bg: #f6f7fb;
  --panel: rgba(0, 0, 0, 0.04);
  --panel-2: rgba(0, 0, 0, 0.06);
  --border: rgba(0, 0, 0, 0.12);
  --text: rgba(0, 0, 0, 0.92);
  --muted: rgba(0, 0, 0, 0.64);
  --muted-2: rgba(0, 0, 0, 0.5);
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.16);
  --page-bg: radial-gradient(1000px 800px at 20% 10%, rgba(167, 139, 250, 0.14), rgba(0, 0, 0, 0)) ,
    radial-gradient(900px 700px at 70% 40%, rgba(110, 231, 255, 0.12), rgba(0, 0, 0, 0)) ,
    linear-gradient(180deg, #ffffff 0%, var(--bg) 70%);
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  color: var(--text);
  background: var(--page-bg);
}

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

a[href] {
  cursor: pointer;
}

/* Skip link — visible on focus for keyboard/screen-reader users */
.skip-link {
  position: absolute;
  top: -9999px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--bg);
  color: var(--accent);
  border: 2px solid var(--accent);
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 700;
  z-index: 9999;
  white-space: nowrap;
}

.skip-link:focus-visible {
  top: 12px;
}

.app-shell {
  display: grid;
  grid-template-columns: 340px 1fr;
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 18px;
  border-right: 1px solid var(--border);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.02));
  backdrop-filter: blur(12px);
}

.brand {
  display: flex;
  gap: 12px;
  align-items: center;
  padding: 10px 10px 14px 10px;
}

.brand-mark {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  background: radial-gradient(circle at 30% 30%, var(--accent) 0%, rgba(110, 231, 255, 0) 55%),
    radial-gradient(circle at 70% 80%, var(--accent-2) 0%, rgba(167, 139, 250, 0) 58%),
    linear-gradient(135deg, rgba(255, 255, 255, 0.2), rgba(255, 255, 255, 0));
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}

.brand-title {
  font-size: 15px;
  letter-spacing: 0.2px;
  font-weight: 640;
}

.brand-subtitle {
  margin-top: 2px;
  font-size: 12px;
  color: var(--muted);
}

.sidebar-controls {
  padding: 6px 10px 14px 10px;
}

.nav {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 8px 10px;
}

.nav-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
}

.nav-title {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.nav-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
  overflow: auto;
  max-height: calc(100vh - 260px);
  padding-right: 2px;
}

.nav-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 11px 10px;
  min-height: 44px;
  border-radius: 12px;
  border: 1px solid transparent;
  background: transparent;
  cursor: pointer;
  transition: transform 150ms ease, background 150ms ease, border-color 150ms ease;
}

.nav-item:hover {
  background: var(--panel);
  border-color: var(--border);
}

.nav-item:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-color: var(--focus-border);
}

.nav-item[aria-current="page"] {
  background: linear-gradient(135deg, rgba(110, 231, 255, 0.12), rgba(167, 139, 250, 0.1));
  border-color: rgba(110, 231, 255, 0.22);
}

.nav-item-title {
  font-size: 13px;
  color: var(--text);
  font-weight: 560;
}

.pill {
  font-size: 12px;
  color: var(--muted);
  padding: 2px 8px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.18);
}

.rating-pill {
  color: var(--text);
  border-color: rgba(110, 231, 255, 0.22);
  background: rgba(110, 231, 255, 0.08);
}

.sidebar-footer {
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 18px;
  display: grid;
  gap: 10px;
}

.main {
  padding: 18px;
}

.site-footer {
  margin-top: 14px;
  padding: 14px 2px 2px 2px;
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  color: var(--muted);
  font-size: 13px;
}

.crumb {
  color: var(--muted);
}

.crumb-strong {
  color: var(--text);
  font-weight: 600;
}

.content {
  margin-top: 16px;
  border-radius: var(--radius);
  padding: 18px;
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.16);
  min-height: calc(100vh - 120px);
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.045), rgba(0, 0, 0, 0.05));
  padding: 14px;
  box-shadow: 0 16px 45px rgba(0, 0, 0, 0.35);
  transition: transform 120ms ease, border-color 120ms ease;
}

.card:hover {
  transform: translateY(-1px);
  border-color: rgba(110, 231, 255, 0.24);
}

.card-title {
  font-weight: 640;
  font-size: 14px;
  color: var(--text);
}

.card-meta {
  margin-top: 6px;
  font-size: 12px;
  color: var(--muted);
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.card-desc {
  margin-top: 10px;
  font-size: 13px;
  color: var(--muted);
  line-height: 1.4;
  min-height: 38px;
}

.card-actions {
  margin-top: 12px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
}

.link {
  color: var(--accent);
  font-weight: 560;
  font-size: 13px;
}

.link:hover {
  text-decoration: underline;
}

.link:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.button {
  border: 1px solid var(--border);
  background: linear-gradient(135deg, rgba(110, 231, 255, 0.14), rgba(167, 139, 250, 0.12));
  color: var(--text);
  padding: 10px 12px;
  border-radius: 12px;
  font-weight: 650;
  font-size: 13px;
  cursor: pointer;
  transition: transform 150ms ease, border-color 150ms ease, background 150ms ease;
  min-height: 44px;
}

.button:hover {
  transform: translateY(-1px);
  border-color: rgba(110, 231, 255, 0.22);
}

.button:active {
  transform: translateY(0);
}

.button-secondary {
  background: rgba(255, 255, 255, 0.05);
}

.button-ghost {
  background: transparent;
  border-color: transparent;
  color: var(--muted);
}

.button-ghost:hover {
  border-color: var(--border);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
  transform: none;
}

.field {
  display: grid;
  gap: 6px;
}

.field-inline {
  grid-template-columns: 70px 1fr;
  align-items: center;
}

.field-label {
  font-size: 12px;
  color: var(--muted);
}

.input,
.select {
  width: 100%;
  padding: 11px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.32);
  color: var(--text);
  outline: none;
}

.input::placeholder {
  color: rgba(255, 255, 255, 0.35);
}

.input:focus-visible,
.select:focus-visible,
.button:focus-visible {
  box-shadow: var(--focus-ring);
  border-color: var(--focus-border);
  outline: none;
}

/* Fallback for browsers that don't support :focus-visible */
@supports not selector(:focus-visible) {
  .input:focus, .select:focus, .button:focus {
    box-shadow: var(--focus-ring);
    border-color: var(--focus-border);
  }
}

.calc {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 14px;
}

.panel {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--panel);
  padding: 14px;
}

.panel-title {
  font-family: var(--font-heading);
  font-weight: 700;
  margin: 0;
  font-size: 14px;
}

.panel-subtitle {
  margin-top: 6px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.5;
}

.rating {
  margin-top: 12px;
}

.stars {
  display: flex;
  gap: 6px;
  margin-top: 6px;
  align-items: center;
}

.star-btn {
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.18);
  color: var(--muted);
  border-radius: 10px;
  padding: 6px 8px;
  cursor: pointer;
  line-height: 1;
  font-size: 14px;
  transition: transform 120ms ease, border-color 120ms ease, background 120ms ease, color 120ms ease;
}

.star-btn:hover {
  transform: translateY(-1px);
  border-color: rgba(110, 231, 255, 0.22);
  color: var(--text);
}

.star-btn:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-color: var(--focus-border);
}

.star-btn.on {
  color: var(--text);
  border-color: rgba(110, 231, 255, 0.22);
  background: rgba(110, 231, 255, 0.08);
}

.form {
  margin-top: 14px;
  display: grid;
  gap: 12px;
}

.outputs {
  display: grid;
  gap: 10px;
  margin-top: 12px;
}

.plot {
  margin-top: 14px;
}

.plot-canvas {
  margin-top: 10px;
  height: 220px;
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.18);
  border-radius: 12px;
  padding: 8px;
}

.plot-canvas canvas {
  width: 100% !important;
  height: 100% !important;
}

.plot-empty {
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
}

.history {
  margin-top: 14px;
}

.history-list {
  margin-top: 10px;
  display: grid;
  gap: 8px;
}

.history-item {
  width: 100%;
  text-align: left;
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.22);
  border-radius: 12px;
  padding: 10px 12px;
  color: var(--text);
  cursor: pointer;
  transition: border-color 120ms ease, transform 120ms ease, background 120ms ease;
}

.history-item:hover {
  transform: translateY(-1px);
  border-color: rgba(110, 231, 255, 0.24);
  background: rgba(0, 0, 0, 0.28);
}

.history-item:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-color: var(--focus-border);
}

.history-summary {
  font-size: 13px;
  font-weight: 650;
  line-height: 1.35;
}

.history-meta {
  margin-top: 4px;
  font-size: 12px;
  color: var(--muted);
}

.history-empty {
  border: 1px dashed var(--border);
  border-radius: 12px;
  padding: 10px 12px;
  color: var(--muted);
  font-size: 13px;
}

.output {
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.28);
  border-radius: 12px;
  padding: 10px 12px;
  display: grid;
  gap: 4px;
}

.output-label {
  font-size: 12px;
  color: var(--muted);
}

.output-value {
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.output-value.muted {
  color: rgba(255, 255, 255, 0.45);
}

.row {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
}

.small {
  font-size: 12px;
  color: var(--muted);
}

.notice {
  border: 1px solid rgba(110, 231, 255, 0.24);
  background: rgba(110, 231, 255, 0.08);
  border-radius: 12px;
  padding: 12px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.45;
}

.recent {
  margin-bottom: 14px;
}

.recent-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
}

.recent-card {
  display: block;
}

.recent-card .card-desc {
  min-height: 0;
}

.hero {
  border: 1px solid var(--border);
  background: linear-gradient(135deg, rgba(110, 231, 255, 0.08), rgba(167, 139, 250, 0.08));
  border-radius: var(--radius);
  padding: 14px;
  margin-bottom: 14px;
  box-shadow: var(--shadow);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  gap: 14px;
  align-items: center;
}

.hero-eyebrow {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 650;
}

.hero-title {
  margin-top: 8px;
  font-family: var(--font-heading);
  font-size: 28px;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.hero-subtitle {
  margin-top: 10px;
  font-size: 13px;
  color: var(--muted);
  line-height: 1.5;
  max-width: 54ch;
}

.sci-calc {
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.16);
  border-radius: 16px;
  padding: 12px;
}

.sci-display {
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.24);
  border-radius: 12px;
  padding: 10px 12px;
}

.sci-display-top {
  font-size: 12px;
  color: var(--muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sci-display-main {
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.sci-keys {
  margin-top: 10px;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
}

.sci-key {
  appearance: none;
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.18);
  border-radius: 12px;
  padding: 10px;
  min-height: 44px;
  font-size: 12px;
  color: var(--text);
  font-weight: 700;
  font-family: var(--font-mono);
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  cursor: pointer;
  user-select: none;
  transition: transform 150ms ease, border-color 150ms ease, background 150ms ease, color 150ms ease;
}

.sci-key:hover {
  transform: translateY(-1px);
  border-color: rgba(110, 231, 255, 0.22);
}

.sci-key:active {
  transform: translateY(0);
}

.sci-key:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-color: var(--focus-border);
}

.sci-key-accent {
  border-color: rgba(110, 231, 255, 0.22);
  background: rgba(110, 231, 255, 0.1);
}

.sci-key-wide {
  grid-column: span 2;
}

.sci-key-eq {
  grid-column: span 4;
  border-color: rgba(110, 231, 255, 0.22);
  background: linear-gradient(135deg, rgba(110, 231, 255, 0.18), rgba(167, 139, 250, 0.14));
}

.home-find {
  display: grid;
  gap: 10px;
  margin-bottom: 12px;
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  border: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.2);
  color: var(--muted);
  border-radius: 999px;
  padding: 7px 10px;
  font-size: 12px;
  cursor: pointer;
  transition: transform 120ms ease, border-color 120ms ease, background 120ms ease, color 120ms ease;
}

.tag:hover {
  transform: translateY(-1px);
  border-color: rgba(110, 231, 255, 0.22);
  color: var(--text);
}

.tag:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-color: var(--focus-border);
}

.tag.active {
  background: linear-gradient(135deg, rgba(110, 231, 255, 0.14), rgba(167, 139, 250, 0.12));
  border-color: rgba(110, 231, 255, 0.22);
  color: var(--text);
}

@media (max-width: 980px) {
  .app-shell {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: relative;
    height: auto;
  }
  .nav-list {
    max-height: 320px;
  }
  .calc {
    grid-template-columns: 1fr;
  }
  .grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .sidebar-footer {
    position: relative;
    left: 0;
    right: 0;
    bottom: 0;
    margin-top: 12px;
  }
}

@media (max-width: 640px) {
  .grid {
    grid-template-columns: 1fr;
  }
  .field-inline {
    grid-template-columns: 1fr;
  }
}

/* Respect user's motion preferences */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}