/* ============================================
   PX CONVERT — Design Tokens & Styles
   Art direction: Technical / developer / data
   Display: JetBrains Mono (monospace)
   Body: General Sans (clean sans)
   ============================================ */

:root {
  /* Typography */
  --font-display: 'JetBrains Mono', 'Courier New', monospace;
  --font-body: 'General Sans', 'Helvetica Neue', sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  /* Type scale */
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);
  --text-2xl:  clamp(2rem,     1.2rem  + 2.5vw,  3rem);

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;

  /* Transition */
  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Content widths */
  --content-default: 960px;
  --content-wide: 1100px;
}

/* ---- LIGHT MODE ---- */
:root, [data-theme="light"] {
  --color-bg:             #f4f5f7;
  --color-surface:        #ffffff;
  --color-surface-2:      #f9fafb;
  --color-surface-offset: #eef0f3;
  --color-divider:        #dde0e6;
  --color-border:         #cdd1d9;

  --color-text:           #1a1d24;
  --color-text-muted:     #6b7280;
  --color-text-faint:     #9ca3af;
  --color-text-inverse:   #f9fafb;

  --color-primary:        #2563eb;
  --color-primary-hover:  #1d4ed8;
  --color-primary-active: #1e40af;
  --color-primary-light:  #dbeafe;

  --color-success:        #16a34a;
  --color-error:          #dc2626;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.07);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.10);
}

/* ---- DARK MODE ---- */
[data-theme="dark"] {
  --color-bg:             #0f1117;
  --color-surface:        #181a22;
  --color-surface-2:      #1e2029;
  --color-surface-offset: #151720;
  --color-divider:        #2a2d38;
  --color-border:         #363946;

  --color-text:           #e2e4ea;
  --color-text-muted:     #8b8f9e;
  --color-text-faint:     #585c6a;
  --color-text-inverse:   #1a1d24;

  --color-primary:        #60a5fa;
  --color-primary-hover:  #93c5fd;
  --color-primary-active: #3b82f6;
  --color-primary-light:  rgba(96,165,250,0.12);

  --color-success:        #4ade80;
  --color-error:          #f87171;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.5);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg:             #0f1117;
    --color-surface:        #181a22;
    --color-surface-2:      #1e2029;
    --color-surface-offset: #151720;
    --color-divider:        #2a2d38;
    --color-border:         #363946;
    --color-text:           #e2e4ea;
    --color-text-muted:     #8b8f9e;
    --color-text-faint:     #585c6a;
    --color-text-inverse:   #1a1d24;
    --color-primary:        #60a5fa;
    --color-primary-hover:  #93c5fd;
    --color-primary-active: #3b82f6;
    --color-primary-light:  rgba(96,165,250,0.12);
    --color-success:        #4ade80;
    --color-error:          #f87171;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
    --shadow-lg: 0 12px 32px rgba(0,0,0,0.5);
  }
}

/* ============================================
   HEADER
   ============================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-divider);
  backdrop-filter: blur(12px);
}

.header-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  text-decoration: none;
  color: var(--color-text);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: var(--text-sm);
  letter-spacing: -0.02em;
}
.logo svg { flex-shrink: 0; }

.header-nav {
  display: flex;
  gap: var(--space-5);
  margin-left: auto;
}
.header-nav a {
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  font-weight: 500;
}
.header-nav a:hover { color: var(--color-text); }

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
}
.theme-toggle:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}

/* ============================================
   HERO
   ============================================ */

.hero {
  padding: clamp(var(--space-10), 5vw, var(--space-16)) var(--space-6) clamp(var(--space-6), 3vw, var(--space-10));
}

.hero-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--color-text);
}

.hero-sub {
  margin-top: var(--space-2);
  font-size: var(--text-base);
  color: var(--color-text-muted);
}

/* ============================================
   CONVERTER CARD
   ============================================ */

.converter-section {
  padding: 0 var(--space-6) clamp(var(--space-10), 5vw, var(--space-20));
}

.converter-card {
  max-width: var(--content-wide);
  margin: 0 auto;
  background: var(--color-surface);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

/* Settings bar */
.settings-bar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-6);
  background: var(--color-surface-2);
  border-bottom: 1px solid var(--color-divider);
}

.setting {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  min-width: 140px;
}
.setting label {
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.setting-input-wrap {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-1) var(--space-2);
}
.setting-input-wrap input {
  width: 70px;
  border: none;
  background: none;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 500;
  padding: 0;
}
.setting-input-wrap input:focus { outline: none; }
.setting-unit {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

/* Unit grid: 4 cols on desktop, minmax(0,1fr) prevents content blowout */
.unit-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  background: var(--color-divider);
  padding: 0;
}

/* vh field (7th child): span remaining cols to fill the row */
.unit-field:nth-child(7) {
  grid-column: span 2;
}

.unit-field {
  background: var(--color-surface);
  padding: var(--space-4) var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  position: relative;
}
.unit-field.active {
  background: var(--color-primary-light);
}

.unit-field label {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  cursor: default;
}

.unit-label {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.unit-desc {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.input-row {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}
.input-row input {
  flex: 1;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 600;
  background: none;
  border: none;
  color: var(--color-text);
  padding: var(--space-1) 0;
  min-width: 0;
  width: 0;
  letter-spacing: -0.02em;
  overflow: hidden;
  text-overflow: ellipsis;
}
.input-row input::placeholder {
  color: var(--color-text-faint);
  opacity: 0.5;
}
.input-row input:focus { outline: none; }

/* Hide number input spinners */
.input-row input[type="number"]::-webkit-outer-spin-button,
.input-row input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
.input-row input[type="number"] {
  -moz-appearance: textfield;
  appearance: textfield;
}

/* Copy button */
.copy-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  color: var(--color-text-faint);
  flex-shrink: 0;
}
.copy-btn:hover {
  background: var(--color-surface-offset);
  color: var(--color-text-muted);
}
.copy-btn.copied {
  color: var(--color-success);
}

/* Live preview */
.preview-section {
  padding: var(--space-4) var(--space-6);
  border-top: 1px solid var(--color-divider);
  background: var(--color-surface-2);
}

.preview-label {
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-3);
}

.preview-area {
  display: flex;
  align-items: flex-end;
  gap: var(--space-4);
  min-height: 60px;
}

.preview-box {
  background: var(--color-primary-light);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  min-width: 20px;
  min-height: 20px;
  max-width: 100%;
  overflow: hidden;
}

#preview-text {
  font-family: var(--font-body);
  font-weight: 600;
  color: var(--color-primary);
  white-space: nowrap;
}

.preview-ruler {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
}

#preview-ruler-label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-weight: 500;
}

/* ============================================
   REFERENCE TABLE
   ============================================ */

.reference-section {
  padding: clamp(var(--space-10), 5vw, var(--space-20)) var(--space-6);
}

.section-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
}

.section-inner h2 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-2);
}

.section-desc {
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  margin-bottom: var(--space-8);
}

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
}

table th {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  padding: var(--space-3) var(--space-4);
  text-align: left;
  border-bottom: 1px solid var(--color-divider);
  background: var(--color-surface-2);
  white-space: nowrap;
}

table td {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  padding: var(--space-2) var(--space-4);
  border-bottom: 1px solid var(--color-divider);
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
}

table tbody tr:last-child td { border-bottom: none; }
table tbody tr:hover { background: var(--color-surface-offset); }

/* ============================================
   GUIDE
   ============================================ */

.guide-section {
  padding: 0 var(--space-6) clamp(var(--space-10), 5vw, var(--space-20));
}

.guide-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-4);
}

.guide-card {
  background: var(--color-surface);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  padding: var(--space-5) var(--space-6);
}

.guide-card h3 {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  font-weight: 700;
  margin-bottom: var(--space-2);
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.guide-tag {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--color-primary);
  background: var(--color-primary-light);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
}

.guide-card p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.65;
}

/* ============================================
   FOOTER
   ============================================ */

.site-footer {
  border-top: 1px solid var(--color-divider);
  padding: var(--space-8) var(--space-6);
}

.footer-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-4);
}

.footer-inner p {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.footer-inner a {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  text-decoration: none;
}
.footer-inner a:hover {
  color: var(--color-text-muted);
}

/* ============================================
   TOAST
   ============================================ */

.toast {
  position: fixed;
  bottom: var(--space-6);
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--color-text);
  color: var(--color-text-inverse);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 500;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  opacity: 0;
  pointer-events: none;
  transition: transform 0.3s ease, opacity 0.3s ease;
  z-index: 200;
}
.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ============================================
   RESPONSIVE
   ============================================ */

@media (max-width: 640px) {
  .header-nav { display: none; }
  
  .hero { padding: var(--space-6) var(--space-4) var(--space-4); }
  .converter-section { padding: 0 var(--space-3) var(--space-10); }
  
  .settings-bar {
    padding: var(--space-3) var(--space-4);
    gap: var(--space-3);
  }
  .setting { min-width: calc(50% - var(--space-3)); }
  
  .unit-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .unit-field:nth-child(7) {
    grid-column: span 1;
  }
  .unit-field { padding: var(--space-3) var(--space-4); }
  
  .preview-section { padding: var(--space-3) var(--space-4); }
  
  .reference-section,
  .guide-section { padding-left: var(--space-3); padding-right: var(--space-3); }
  
  .guide-grid { grid-template-columns: 1fr; }
  
  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}