/* ========== Design tokens ========== */
:root {
  /* Dark theme (default) */
  --bg: #0b0f1a;
  --surface: #0f1726;
  --surface-2: #121a2b;
  --text: #e7eaf0;
  --muted: #aab1c3;
  --border: #1f2a44;

  /* Accent */
  --accent: #00f5c9;
  --accent-2: #4cc9f0;

  /* FX */
  --ring: rgba(0, 245, 201, 0.45);
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.45);
  --radius: 14px;
  --radius-sm: 10px;
  --radius-lg: 20px;

  /* Typography */
  --font: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, 'Helvetica Neue',
    Arial, 'Noto Sans', 'Liberation Sans', sans-serif;
}

/* Light theme via pure CSS toggle */
body:has(#theme-toggle:checked) {
  --bg: #f6f7fb;
  --surface: #ffffff;
  --surface-2: #f3f5fa;
  --text: #0f1222;
  --muted: #5c6477;
  --border: #e3e8f0;

  --ring: rgba(76, 201, 240, 0.35);
  --shadow: 0 10px 30px rgba(2, 6, 23, 0.08);
}

/* ========== Base ========== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  margin: 0;
  color: var(--text);
  background: radial-gradient(1200px 600px at 10% -10%, #16213e 0%, transparent 60%),
              radial-gradient(800px 500px at 110% 50%, #0e5666 0%, transparent 55%),
              var(--bg);
  font-family: var(--font);
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Accessible skip link */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: var(--shadow);
}
.skip-link:focus {
  left: 12px;
  top: 12px;
  outline: none;
}

/* ========== Header ========== */
.site-header {
  max-width: 980px;
  margin: 24px auto 12px;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.logo {
  display: inline-grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  font-weight: 700;
  letter-spacing: 0.5px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #061017;
  box-shadow: 0 6px 22px rgba(0, 245, 201, 0.35);
}

.title {
  margin: 0;
  font-size: clamp(18px, 2.2vw, 22px);
  font-weight: 700;
  letter-spacing: 0.2px;
}

/* Theme toggle */
.theme-toggle {
  display: grid;
  place-items: center;
}
.theme-toggle input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}
.theme-toggle .switch {
  --size: 44px;
  width: var(--size);
  height: calc(var(--size) * 0.58);
  border-radius: 999px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  padding: 2px;
  cursor: pointer;
  position: relative;
  transition: background 0.25s ease, border-color 0.25s ease;
}
.theme-toggle .switch::after {
  content: "";
  position: absolute;
  inset: 2px;
  width: calc(50% - 4px);
  border-radius: 999px;
  background: linear-gradient(180deg, var(--surface), var(--surface-2));
  box-shadow: 0 1px 0 rgba(255,255,255,0.06) inset, 0 6px 14px rgba(0,0,0,0.35);
  transform: translateX(0);
  transition: transform 0.25s ease;
}
body:has(#theme-toggle:checked) .theme-toggle .switch::after {
  transform: translateX(100%);
}
.theme-toggle .sun, .theme-toggle .moon {
  font-size: 12px;
  opacity: 0.85;
  user-select: none;
}

/* ========== Layout ========== */
.container {
  max-width: 980px;
  margin: 12px auto 40px;
  padding: 0 20px;
}

.controls {
  display: flex;
  justify-content: center;
  margin: 18px 0 12px;
}

/* ========== Segmented control ========== */
.segmented {
  display: inline-flex;
  gap: 6px;
  padding: 6px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 999px;
}

.seg-option {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  border-radius: 999px;
  cursor: pointer;
  user-select: none;
  color: var(--muted);
  transition: color 0.2s ease;
}
.seg-option input {
  appearance: none;
  position: absolute;
  inset: 0;
  margin: 0;
  opacity: 0;
}
.seg-option:has(input:checked) {
  color: #0a1222;
}
.seg-option:has(input:checked) span {
  position: relative;
  z-index: 1;
}
.seg-option:has(input:checked)::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 6px 16px var(--ring);
}

/* ========== Editor card ========== */
.editor-card {
  position: relative;
  background: linear-gradient(180deg, var(--surface), var(--surface-2));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

/* Neon border glow */
.editor-card::before {
  content: "";
  position: absolute;
  inset: -1px;
  border-radius: calc(var(--radius) + 1px);
  pointer-events: none;
  background: conic-gradient(from 180deg,
    transparent 0 30%,
    rgba(0, 245, 201, 0.15) 30% 40%,
    transparent 40% 70%,
    rgba(76, 201, 240, 0.15) 70% 80%,
    transparent 80% 100%);
  filter: blur(8px);
  opacity: 0.5;
  z-index: 0;
}

.editor-bar {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 16px;
  border-bottom: 1px dashed var(--border);
}

.hint {
  margin: 0;
  font-size: 13px;
  color: var(--muted);
}

.actions {
  display: flex;
  gap: 8px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 36px;
  padding: 0 12px;
  font: 500 14px/1 var(--font);
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: transform 0.05s ease, box-shadow 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}
.btn .icon {
  width: 18px;
  height: 18px;
  flex: 0 0 18px;
}
.btn:hover {
  box-shadow: 0 8px 18px rgba(0,0,0,0.25);
}
.btn:active {
  transform: translateY(1px);
}

/* Variants */
.btn.ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--muted);
}
.btn.ghost:hover {
  background: var(--surface-2);
  color: var(--text);
}

.btn.solid {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0a1222;
  border-color: transparent;
  box-shadow: 0 10px 24px var(--ring);
}
.btn.solid:hover {
  filter: brightness(1.05);
}

/* Textarea */
#converter {
  position: relative;
  z-index: 1;
  width: 100%;
  min-height: 340px;
  height: 44vh;
  resize: vertical;
  padding: 16px 16px 18px;
  border: none;
  outline: none;
  background: transparent;
  color: var(--text);
  font: 500 18px/1.6 var(--font);
  caret-color: var(--accent);
}
#converter::placeholder {
  color: color-mix(in oklab, var(--muted) 80%, transparent);
}

/* Focus ring for keyboard users */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Footer */
.site-footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  justify-content: center;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 13px;
}
.site-footer a {
  color: inherit;
  text-decoration: underline;
  text-decoration-color: color-mix(in oklab, var(--muted) 60%, transparent);
  text-underline-offset: 3px;
}
.site-footer .dot {
  opacity: 0.6;
}

/* Links */
a {
  color: var(--accent-2);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

/* Responsiveness */
@media (max-width: 560px) {
  .editor-bar {
    flex-direction: column;
    align-items: stretch;
  }
  .actions {
    justify-content: space-between;
  }
}