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

:root {
  --bg: #ffffff;
  --text: #1a1a1a;
  --text-muted: #6b7280;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --border: #e5e7eb;
  --nav-bg: #f9fafb;
  --nav-width: 200px;
  --header-height: 56px;
}

[data-theme="dark"] {
  --bg: #0f1117;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --accent: #60a5fa;
  --accent-hover: #93c5fd;
  --border: #1e293b;
  --nav-bg: #0a0d14;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.15s, color 0.15s;
}

/* Site header */
#site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  height: var(--header-height);
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  transition: background 0.15s, border-color 0.15s;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.site-name {
  font-weight: 600;
  font-size: 1rem;
  color: var(--text);
  text-decoration: none;
  transition: color 0.15s;
}

.site-name:hover {
  color: var(--accent);
}

#dark-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  padding: 0.35rem 0.75rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  transition: border-color 0.15s, color 0.15s;
}

#dark-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

#nav-hamburger {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  padding: 0.35rem 0.6rem;
  font-size: 1rem;
  line-height: 1;
  color: var(--text-muted);
  transition: border-color 0.15s, color 0.15s;
}

#nav-hamburger:hover {
  border-color: var(--accent);
  color: var(--accent);
}

#nav-mobile-menu {
  display: none;
  position: absolute;
  top: 100%;
  right: 1rem;
  min-width: 160px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
  padding: 0.375rem 0;
  z-index: 200;
}

#nav-mobile-menu.open {
  display: block;
}

.nav-menu-item {
  display: block;
  width: 100%;
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  color: var(--text-muted);
  text-decoration: none;
  text-align: left;
  background: none;
  border: none;
  cursor: pointer;
  transition: background 0.1s, color 0.1s;
  box-sizing: border-box;
}

.nav-menu-item:hover {
  background: color-mix(in srgb, var(--text) 5%, transparent);
  color: var(--text);
}

.nav-menu-item.active {
  color: var(--accent);
  font-weight: 500;
}

.nav-menu-divider {
  height: 1px;
  background: var(--border);
  margin: 0.375rem 0;
}

/* Homepage */
.home-wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 6rem 1.5rem 4rem;
}

.home-wrap h1 {
  font-size: 2.75rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.15;
  margin-bottom: 0.75rem;
}

.home-tagline {
  font-size: 1.125rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.home-links {
  display: flex;
  gap: 1.25rem;
  margin-bottom: 3rem;
}

.home-links a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.15s;
}

.home-links a:hover {
  color: var(--accent);
}

.home-links svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

.tools-card {
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  padding: 1rem 1.5rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  text-decoration: none;
  color: var(--text);
  font-size: 0.975rem;
  font-weight: 500;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.tools-card:hover {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 12%, transparent);
}

.tools-card-arrow {
  color: var(--text-muted);
}

/* Tools shell */
#tools-shell {
  display: flex;
  min-height: calc(100vh - var(--header-height));
}

/* Side nav */
#tools-sidenav {
  width: var(--nav-width);
  flex-shrink: 0;
  background: var(--nav-bg);
  border-right: 1px solid var(--border);
  padding: 1.25rem 0;
  position: sticky;
  top: var(--header-height);
  height: calc(100vh - var(--header-height));
  overflow-y: auto;
  transition: background 0.15s, border-color 0.15s;
}

.sidenav-label {
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 0 1rem 0.5rem;
}

#tools-sidenav a {
  display: block;
  padding: 0.45rem 1rem;
  font-size: 0.875rem;
  color: var(--text-muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: color 0.15s, background 0.15s, border-color 0.15s;
}

#tools-sidenav a:hover {
  color: var(--text);
  background: color-mix(in srgb, var(--text) 5%, transparent);
}

#tools-sidenav a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 8%, transparent);
  font-weight: 500;
}


/* Main content */
#tools-main {
  flex: 1;
  min-width: 0;
  padding: 2rem;
}

/* Tool header */
.tool-header {
  margin-bottom: 1.5rem;
}

.tool-header h1 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.tool-header p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Tool IO */
.tool-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.tool-io {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1rem;
}

.tool-io-panel {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  min-width: 0;
}

.panel-label-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.panel-label-row label,
.tool-io-panel > label {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.tool-io-panel textarea,
pre.tool-output {
  font-family: "JetBrains Mono", "Fira Code", "Cascadia Code", ui-monospace, "Courier New", monospace;
  font-size: 0.8rem;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  line-height: 1.6;
  min-height: 340px;
  transition: border-color 0.15s;
}

.tool-io-panel textarea {
  width: 100%;
  resize: vertical;
  background: var(--bg);
}

.tool-io-panel textarea:focus {
  outline: none;
  border-color: var(--accent);
}

pre.tool-output {
  background: var(--nav-bg);
  overflow: auto;
  white-space: pre;
  margin: 0;
}

/* Buttons */
.btn-primary {
  padding: 0.5rem 1.25rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-secondary {
  padding: 0.4rem 0.875rem;
  background: none;
  color: var(--text-muted);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s;
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Error */
.tool-error {
  padding: 0.6rem 0.875rem;
  background: color-mix(in srgb, #ef4444 8%, transparent);
  border: 1px solid color-mix(in srgb, #ef4444 25%, transparent);
  border-radius: 6px;
  color: #ef4444;
  font-size: 0.85rem;
  display: none;
  margin-bottom: 1rem;
}

/* JSON syntax highlighting */
.json-key  { color: #2563eb; }
.json-str  { color: #16a34a; }
.json-num  { color: #d97706; }
.json-bool { color: #7c3aed; }
.json-null { color: var(--text-muted); }

[data-theme="dark"] .json-key  { color: #60a5fa; }
[data-theme="dark"] .json-str  { color: #4ade80; }
[data-theme="dark"] .json-num  { color: #fbbf24; }
[data-theme="dark"] .json-bool { color: #c084fc; }

/* Tools landing */
.tools-landing-intro {
  margin-bottom: 2rem;
  color: var(--text-muted);
  font-size: 0.975rem;
  line-height: 1.65;
}

.tool-cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 1rem;
}

.tool-card-item {
  display: block;
  padding: 1rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.15s, box-shadow 0.15s;
}

.tool-card-item:hover {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 10%, transparent);
}

.tool-card-item h3 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.35rem;
}

.tool-card-item p {
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Epoch converter */
.epoch-input-row {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
  max-width: 500px;
}

.epoch-text-input {
  flex: 1;
  padding: 0.5rem 0.875rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  color: var(--text);
  font-size: 1rem;
  font-family: ui-monospace, monospace;
  transition: border-color 0.15s;
}

.epoch-text-input:focus {
  outline: none;
  border-color: var(--accent);
}

.epoch-hint {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

.epoch-result-box {
  padding: 1.25rem 1.5rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--nav-bg);
  max-width: 560px;
  margin-bottom: 2rem;
}

.epoch-result-grid {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 0.65rem 1rem;
  font-size: 0.9rem;
}

.epoch-label {
  color: var(--text-muted);
  font-weight: 500;
}

.epoch-value {
  font-family: ui-monospace, monospace;
  word-break: break-all;
}

.epoch-current {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.epoch-current strong {
  font-weight: 500;
  color: var(--text);
  font-family: ui-monospace, monospace;
}

/* Responsive */
@media (max-width: 767px) {
  #dark-toggle {
    display: none;
  }

  #nav-hamburger {
    display: block;
  }

  #tools-sidenav {
    display: none;
  }

  .tool-io {
    grid-template-columns: 1fr;
  }

  #tools-main {
    padding: 1.25rem;
  }

  .home-wrap {
    padding: 4rem 1.25rem 3rem;
  }

  .home-wrap h1 {
    font-size: 2.25rem;
  }
}