:root {
  --color-bg: #070b14;
  --color-bg-soft: #0c1220;
  --color-panel: #111827;
  --color-panel-soft: #151e2e;
  --color-border: #293447;
  --color-text: #f8fafc;
  --color-muted: #a7b4c5;
  --color-subtle: #718096;
  --color-accent: #38d5ff;
  --color-accent-strong: #09a7f7;
  --color-error: #ff7a90;
  --color-success: #7ee7b8;
  --shadow-panel: 0 22px 70px rgba(0, 0, 0, 0.34);
  --radius-lg: 8px;
  --radius-md: 6px;
  --max-width: 1180px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  margin: 0;
  background:
    linear-gradient(180deg, rgba(56, 213, 255, 0.08), transparent 260px),
    var(--color-bg);
  color: var(--color-text);
  font-size: 16px;
  line-height: 1.6;
}

button,
textarea {
  font: inherit;
}

button {
  cursor: pointer;
}

code {
  color: var(--color-accent);
}

.skip-link {
  position: absolute;
  left: 16px;
  top: -48px;
  z-index: 10;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  background: var(--color-accent);
  color: #04111f;
  font-weight: 800;
  text-decoration: none;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: 16px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.site-header,
.site-footer,
.product-intro,
.converter-shell,
.examples,
.notes {
  width: min(100% - 32px, var(--max-width));
  margin-inline: auto;
}

.site-header {
  padding: 18px 0 10px;
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand,
.nav-links a {
  color: var(--color-text);
  text-decoration: none;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  letter-spacing: 0;
}

.brand-mark {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  border: 1px solid rgba(56, 213, 255, 0.45);
  border-radius: var(--radius-md);
  background: rgba(56, 213, 255, 0.12);
  color: var(--color-accent);
}

.nav-links {
  display: inline-flex;
  gap: 14px;
  color: var(--color-muted);
  font-size: 0.92rem;
}

.nav-links a {
  color: var(--color-muted);
}

.nav-links a:hover {
  color: var(--color-text);
}

.product-intro {
  display: grid;
  gap: 14px;
  padding: 42px 0 20px;
}

.eyebrow,
.section-label {
  margin: 0 0 8px;
  color: var(--color-accent);
  font-size: 0.78rem;
  font-weight: 800;
  text-transform: uppercase;
}

.product-intro h1 {
  max-width: 820px;
  margin: 0;
  font-size: clamp(2rem, 7vw, 4.25rem);
  line-height: 1.08;
  letter-spacing: 0;
}

.hero-description {
  max-width: 700px;
  margin: 0;
  color: var(--color-muted);
  font-size: 1.02rem;
}

.converter-shell {
  display: grid;
  gap: 16px;
  padding: 14px 0 42px;
}

.panel {
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: rgba(17, 24, 39, 0.9);
  box-shadow: var(--shadow-panel);
}

.panel-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
}

.panel-heading h2,
.section-header h2 {
  margin: 0;
  font-size: 1.22rem;
  line-height: 1.25;
}

.char-count {
  flex: 0 0 auto;
  color: var(--color-subtle);
  font-size: 0.88rem;
}

.mode-group {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  padding: 0;
  margin: 0 0 16px;
  border: 0;
}

.mode-group legend {
  margin-bottom: 8px;
  color: var(--color-muted);
  font-size: 0.92rem;
  font-weight: 750;
}

.mode-option {
  position: relative;
}

.mode-option input {
  position: absolute;
  inset: 0;
  opacity: 0;
}

.mode-option span {
  display: grid;
  min-height: 42px;
  place-items: center;
  padding: 0 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: rgba(12, 18, 32, 0.92);
  color: var(--color-muted);
  font-size: 0.92rem;
  font-weight: 760;
  text-align: center;
  transition: border-color 0.18s ease, color 0.18s ease, background 0.18s ease;
}

.mode-option input:checked + span {
  border-color: rgba(56, 213, 255, 0.72);
  background: rgba(56, 213, 255, 0.12);
  color: var(--color-text);
}

.mode-option input:focus-visible + span {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.input-label {
  display: block;
  margin-bottom: 8px;
  color: var(--color-muted);
  font-size: 0.92rem;
  font-weight: 750;
}

textarea {
  display: block;
  width: 100%;
  min-height: 220px;
  resize: vertical;
  padding: 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-bg-soft);
  color: var(--color-text);
  outline: none;
}

textarea::placeholder {
  color: #66768a;
}

textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(56, 213, 255, 0.14);
}

.actions {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin-top: 14px;
}

.button,
.copy-button {
  min-height: 44px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  font-weight: 800;
  transition: transform 0.18s ease, background 0.18s ease, border-color 0.18s ease, opacity 0.18s ease;
}

.button:hover,
.copy-button:hover {
  transform: translateY(-1px);
}

.button-primary {
  background: var(--color-accent);
  color: #03111f;
}

.button-primary:hover {
  background: var(--color-accent-strong);
}

.button-secondary,
.copy-button {
  border-color: var(--color-border);
  background: rgba(12, 18, 32, 0.95);
  color: var(--color-text);
}

.button:disabled,
.copy-button:disabled {
  cursor: not-allowed;
  opacity: 0.48;
  transform: none;
}

.message {
  min-height: 24px;
  margin: 12px 0 0;
  color: var(--color-muted);
  font-size: 0.92rem;
}

.message.is-error {
  color: var(--color-error);
}

.message.is-success {
  color: var(--color-success);
}

.result-box {
  min-height: 360px;
  padding: 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-bg-soft);
  color: var(--color-text);
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.result-box:focus {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.placeholder {
  margin: 0;
  color: var(--color-subtle);
}

.examples,
.notes {
  padding: 18px 0 56px;
}

.section-header {
  margin-bottom: 16px;
}

.example-grid,
.note-grid {
  display: grid;
  gap: 12px;
}

.example-card,
.note-grid p {
  margin: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: rgba(12, 18, 32, 0.92);
  color: var(--color-text);
}

.example-card {
  width: 100%;
  padding: 16px;
  text-align: left;
}

.example-card span {
  display: inline-flex;
  margin-bottom: 10px;
  color: var(--color-accent);
  font-size: 0.78rem;
  font-weight: 850;
}

.example-card strong {
  display: block;
  margin-bottom: 6px;
  font-size: 1rem;
}

.example-card p,
.note-grid p {
  color: var(--color-muted);
  font-size: 0.92rem;
}

.example-card p {
  margin: 0;
}

.example-card:hover {
  border-color: rgba(56, 213, 255, 0.56);
}

.note-grid p {
  padding: 16px;
}

.site-footer {
  display: grid;
  gap: 6px;
  padding: 24px 0 38px;
  border-top: 1px solid rgba(41, 52, 71, 0.72);
  color: var(--color-subtle);
  font-size: 0.88rem;
}

.site-footer p {
  margin: 0;
}

@media (min-width: 720px) {
  .site-header,
  .site-footer,
  .product-intro,
  .converter-shell,
  .examples,
  .notes {
    width: min(100% - 56px, var(--max-width));
  }

  .product-intro {
    grid-template-columns: minmax(0, 1.1fr) minmax(280px, 0.9fr);
    align-items: end;
    padding-top: 62px;
  }

  .converter-shell {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  }

  .panel {
    padding: 22px;
  }

  .actions {
    grid-template-columns: 1fr auto;
  }

  .button-secondary {
    min-width: 112px;
  }

  .mode-group {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

  .example-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .note-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1040px) {
  .example-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }
}