* {
  box-sizing: border-box;
}

:root {
  --bg-body: #f8fafc;
  --text-primary: #0f172a;
  --bg-card: #ffffff;
  --bg-muted: #f1f5f9;
  --bg-hover: #e2e8f0;
  --border: #e2e8f0;
  --border-input: #d1d5db;
  --border-strong: #94a3b8;
  --text-secondary: #475569;
  --text-muted: #6b7280;
  --text-dim: #94a3b8;
  --text-value: #1f2937;
  --accent: #6366f1;
  --accent-shadow: rgba(99, 102, 241, 0.2);
  --accent-light: #eef2ff;
  --accent-text: #4338ca;
  --btn-bg: #4f46e5;
  --btn-hover: #4338ca;
  --btn-secondary-bg: #ffffff;
  --btn-secondary-border: #c7d2fe;
  --color-error: #dc2626;
  --color-success: #16a34a;
  --result-bg: #f8fafc;
  --shadow-card: 0 10px 24px rgba(15, 23, 42, 0.06);
  --shadow-sm: 0 2px 6px rgba(15, 23, 42, 0.1);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg-body: #0f172a;
    --text-primary: #f1f5f9;
    --bg-card: #1e293b;
    --bg-muted: #334155;
    --bg-hover: #475569;
    --border: #334155;
    --border-input: #475569;
    --border-strong: #64748b;
    --text-secondary: #94a3b8;
    --text-muted: #94a3b8;
    --text-dim: #64748b;
    --text-value: #cbd5e1;
    --accent: #818cf8;
    --accent-shadow: rgba(129, 140, 248, 0.25);
    --accent-light: #312e81;
    --accent-text: #a5b4fc;
    --btn-bg: #6366f1;
    --btn-hover: #818cf8;
    --btn-secondary-bg: #1e293b;
    --btn-secondary-border: #4338ca;
    --color-error: #f87171;
    --color-success: #4ade80;
    --result-bg: #1e293b;
    --shadow-card: 0 10px 24px rgba(0, 0, 0, 0.3);
    --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.4);
    --copy-feedback-text: #0f172a;
  }
}

[data-theme="dark"] {
  --bg-body: #0f172a;
  --text-primary: #f1f5f9;
  --bg-card: #1e293b;
  --bg-muted: #334155;
  --bg-hover: #475569;
  --border: #334155;
  --border-input: #475569;
  --border-strong: #64748b;
  --text-secondary: #94a3b8;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --text-value: #cbd5e1;
  --accent: #818cf8;
  --accent-shadow: rgba(129, 140, 248, 0.25);
  --accent-light: #312e81;
  --accent-text: #a5b4fc;
  --btn-bg: #6366f1;
  --btn-hover: #818cf8;
  --btn-secondary-bg: #1e293b;
  --btn-secondary-border: #4338ca;
  --color-error: #f87171;
  --color-success: #4ade80;
  --result-bg: #1e293b;
  --shadow-card: 0 10px 24px rgba(0, 0, 0, 0.3);
  --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.4);
  --copy-feedback-text: #0f172a;
}

body {
  margin: 0;
  font-family:
    "Inter",
    system-ui,
    -apple-system,
    "Segoe UI",
    sans-serif;
  color: var(--text-primary);
  background: var(--bg-body);
  line-height: 1.6;
}

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

img {
  max-width: 100%;
  display: block;
  border-radius: 12px;
}

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

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

.nav-left {
  display: flex;
  align-items: center;
  gap: 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
}

.brand img {
  width: 28px;
  height: 28px;
}

.nav-links {
  display: flex;
  gap: 16px;
  font-size: 14px;
  color: var(--text-secondary);
}

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 999px;
  margin: 3px 0;
}

.nav-mobile {
  display: none;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-left: auto;
}

.cta-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.btn {
  padding: 10px 16px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  border: 1px solid transparent;
}

.btn.primary {
  background: var(--btn-bg);
  color: #ffffff;
}

.btn.secondary {
  background: var(--btn-secondary-bg);
  color: var(--accent-text);
  border-color: var(--btn-secondary-border);
}

button img {
  border-radius: unset;
}

@media (max-width: 720px) {
  .nav {
    padding: 12px 12px;
  }

  .nav-left .nav-links,
  .nav > .cta-group,
  .nav > .nav-actions > .cta-group {
    display: none;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .nav-mobile {
    display: none;
    padding: 12px 16px 16px;
    border-top: 1px solid var(--border);
  }

  .nav-mobile .nav-links {
    flex-direction: column;
    gap: 12px;
  }

  .nav-mobile .cta-group {
    flex-direction: column;
  }

  .site-header.is-open .nav-mobile {
    display: grid;
    gap: 12px;
  }
}

.hero {
  padding: 64px 0 40px;
}

.hero-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 32px;
  align-items: center;
}

.hero h1 {
  font-size: 42px;
  line-height: 1.1;
  margin: 0 0 16px;
}

.hero p {
  font-size: 18px;
  color: var(--text-secondary);
  margin: 12px 0 24px;
}

.pill {
  display: inline-flex;
  align-items: center;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--accent-light);
  color: var(--accent-text);
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 16px;
}

.section {
  padding: 40px 0;
}

.section h2 {
  font-size: 28px;
  margin: 0 0 16px;
}

.section p {
  color: var(--text-secondary);
  margin: 0 0 20px;
}

.card-grid {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.card {
  background: var(--bg-card);
  border-radius: 16px;
  padding: 20px;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-card);
}

.card h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.card ul {
  padding-left: 18px;
  margin: 0;
  color: var(--text-secondary);
}

.screenshot-grid {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(3, minmax(240px, 1fr));
}

.feature-list {
  display: grid;
  gap: 16px;
}

.feature-item {
  padding: 16px;
  border-radius: 12px;
  background: var(--bg-card);
  border: 1px solid var(--border);
}

.feature-item h4 {
  margin: 0 0 8px;
}

.feature-item p {
  margin: 0;
  color: var(--text-muted);
}

/* ── Demo ──────────────────────────────────────────────────────── */

.demo-layout {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  margin-top: 24px;
}

.demo-tabs {
  display: flex;
  gap: 8px;
  background: var(--bg-muted);
  padding: 6px;
  border-radius: 12px;
  margin-bottom: 16px;
  font-family: inherit;
}

.demo-tab {
  flex: 1;
  border: none;
  background: transparent;
  padding: 8px 10px;
  border-radius: 10px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-secondary);
  font-family: inherit;
}

.demo-tab.is-active {
  background: var(--bg-card);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}

.demo-panel {
  display: none;
}

.demo-panel.is-active {
  display: grid;
}

.demo-panel input,
.demo-panel select {
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border-input);
  font-size: 14px;
  width: 100%;
  background: var(--bg-card);
  color: var(--text-primary);
}

/* ── Number input spinners ─────────────────────────────────────── */

input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

input[type="number"] {
  appearance: textfield;
  -moz-appearance: textfield;
}

/* ── Floating outlined fields ─────────────────────────────────── */

.floating-field {
  position: relative;
}

.floating-field input,
.floating-field select {
  padding: 8px;
  font-family:
    "JetBrains Mono", "SF Mono", "Consolas", "Liberation Mono", "Menlo",
    monospace;
}

.floating-field input:focus,
.floating-field select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-shadow);
}

.floating-field select {
  cursor: pointer;
}

.floating-field label {
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 13px;
  color: var(--text-muted);
  font-weight: 600;
  pointer-events: none;
  transition: 0.15s ease all;
  background: var(--bg-card);
  padding: 0 3px;
  margin: 0;
  white-space: nowrap;
}

.floating-field input:focus + label,
.floating-field input:not(:placeholder-shown) + label,
.floating-field input.has-value + label {
  top: 0;
  font-size: 10px;
  letter-spacing: 0.04em;
}

.floating-field input:focus + label {
  color: var(--accent);
}

.floating-field select + label {
  top: 0;
  font-size: 10px;
  letter-spacing: 0.04em;
}

.floating-field select:focus + label {
  color: var(--accent);
}

/* ── Field error state ────────────────────────────────────────── */

.floating-field.field-error input {
  border-color: var(--color-error);
}

.floating-field.field-error input:focus {
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.2);
}

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

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

.hint p {
  margin: 5px;
}

.preset-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
  margin-top: 10px;
}

.preset-row :last-child {
  flex: 1;
}

.demo-action {
  padding: 10px 14px;
  border-radius: 10px;
  border: none;
  background: var(--btn-bg);
  color: #ffffff;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
}

.demo-error {
  margin-top: 15px;
  font-size: 12px;
  color: var(--color-error);
  min-height: 16px;
}

.time-presets {
  display: flex;
  align-items: center;
  gap: 4px;
}

.preset-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  padding: 0;
  border: 1px solid var(--border-input);
  border-radius: 6px;
  background: transparent;
  cursor: pointer;
  transition:
    background 0.15s,
    border-color 0.15s;
}

.preset-chip img {
  display: block;
}

.preset-chip:hover {
  background: var(--bg-muted);
  border-color: var(--border-strong);
}

.preset-chip.is-active {
  background: var(--accent-light);
  border-color: var(--accent);
}

/* ── Copy epoch button ────────────────────────────────────────── */

.copy-epoch-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  padding: 0;
  border: 1px solid var(--border-input);
  border-radius: 10px;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  flex-shrink: 0;
  transition:
    color 0.15s,
    background 0.15s,
    border-color 0.15s;
}

.copy-epoch-btn:hover {
  background: var(--bg-muted);
  border-color: var(--border-strong);
  color: var(--text-primary);
}

.copy-epoch-btn.copy-success {
  color: var(--color-success);
  border-color: var(--color-success);
}

.copy-epoch-btn.copy-error {
  color: var(--color-error);
  border-color: var(--color-error);
}

.copy-epoch-btn svg {
  width: 16px;
  height: 16px;
}

/* ── ISO toggle + input ───────────────────────────────────────── */

.iso-toggle-btn {
  padding: 10px 14px;
  border: 1px solid var(--border-input);
  border-radius: 8px;
  background: transparent;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  letter-spacing: 0.03em;
  transition:
    background 0.15s,
    border-color 0.15s,
    color 0.15s;
}

.iso-toggle-btn:hover {
  background: var(--bg-muted);
  border-color: var(--border-strong);
}

.iso-toggle-btn.is-active {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
}

.demo-date-manual-group[hidden] {
  display: none;
}

.demo-iso-input-group {
  display: flex;
  gap: 10px;
}

.demo-iso-input-group[hidden] {
  display: none;
}

.demo-iso-input-group .floating-field label {
  top: 0;
  font-size: 10px;
  letter-spacing: 0.04em;
}

.demo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
  gap: 10px;
  margin-top: 10px;
}

.demo-time-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr)) auto;
}

.demo-output {
  background: var(--result-bg);
  margin-top: 15px;
  border: 1px solid var(--border);
  padding: 12px;
  border-radius: 10px;
  font-size: 13px;
  color: var(--text-primary);
  display: grid;
  grid-template-columns: auto auto 1fr auto;
  column-gap: 6px;
  row-gap: 4px;
  align-items: baseline;
  font-family:
    "JetBrains Mono", "SF Mono", "Consolas", "Liberation Mono", "Menlo",
    monospace;
}

.demo-output > strong {
  white-space: nowrap;
}

.demo-colon {
  color: var(--text-muted);
}

.demo-output > span {
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

.demo-separator {
  grid-column: 1 / -1;
  border-top: 1px solid var(--border);
  margin-top: 4px;
}

/* ── Copy button (shared across demo output and history) ────────── */

.copy-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  padding: 2px;
  border-radius: 4px;
  background: transparent;
  color: var(--text-muted);
  border: none;
  cursor: pointer;
  flex-shrink: 0;
  transition:
    color 0.15s ease,
    background 0.15s ease;
  box-shadow: none !important;
}

.copy-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.copy-btn svg {
  display: block;
  width: 14px;
  height: 14px;
}

.copy-btn.copy-success {
  color: var(--color-success);
}

.copy-btn.copy-error {
  color: var(--color-error);
}

/* ── History ───────────────────────────────────────────────────── */

.history-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.history-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
}

#demo-clear-history {
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 11px;
  background: var(--result-bg);
  color: var(--text-primary);
  border: 1px solid var(--border-input);
  cursor: pointer;
}

#demo-clear-history:hover {
  background: var(--bg-hover);
}

ul.history-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 10px;
}

.history-item {
  padding: 12px;
  border-radius: 12px;
  background: var(--result-bg);
  border: 1px solid var(--border);
  font-family:
    "JetBrains Mono", "SF Mono", "Consolas", "Liberation Mono", "Menlo",
    monospace;
}

.history-epoch {
  font-weight: 700;
  font-size: 13px;
}

.history-top {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 10px;
}

.history-time {
  position: relative;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 11px;
  color: var(--text-dim);
}

.history-lines {
  display: grid;
  grid-template-columns: auto auto 1fr auto;
  column-gap: 6px;
  row-gap: 4px;
  align-items: baseline;
  margin-top: 6px;
  font-size: 12px;
}

.history-colon {
  color: var(--text-muted);
}

.history-label {
  font-weight: 700;
  color: var(--text-primary);
  white-space: nowrap;
}

.history-value {
  color: var(--text-value);
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

/* ── Legal / Footer ────────────────────────────────────────────── */

.legal {
  max-width: 760px;
}

.legal h1 {
  margin-bottom: 8px;
}

.legal p {
  color: var(--text-secondary);
  margin: 0 0 16px;
}

.legal ul {
  padding-left: 20px;
  color: var(--text-secondary);
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 24px 0;
  color: var(--text-muted);
  font-size: 13px;
}

.footer-grid {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-links {
  display: flex;
  gap: 12px;
}

.muted {
  color: var(--text-dim);
  font-size: 13px;
}

/* ── Theme toggle (website) ────────────────────────────────────── */

.theme-toggle {
  position: relative;
}

.theme-toggle-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg-card);
  color: var(--text-secondary);
  cursor: pointer;
  transition:
    background 0.15s,
    border-color 0.15s;
}

.theme-toggle-btn:hover {
  background: var(--bg-muted);
  border-color: var(--border-strong);
}

.theme-toggle-btn svg {
  width: 18px;
  height: 18px;
}

.theme-menu {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  z-index: 100;
  min-width: 140px;
  padding: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  box-shadow: var(--shadow-card);
}

.theme-menu-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 8px 10px;
  border: none;
  border-radius: 8px;
  background: transparent;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
}

.theme-menu-item:hover {
  background: var(--bg-muted);
}

.theme-menu-item.is-active {
  color: var(--accent);
  font-weight: 600;
}

.theme-menu-item svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

[data-theme="dark"] .nav-toggle img {
  filter: invert(1);
}