/* ============================================
   S-DES Calculator - Style Sheet
   Theme: Black, Yellow (#FFD600), White
   ============================================ */

:root {
  --black: #0a0a0a;
  --black-soft: #141414;
  --black-card: #1a1a1a;
  --black-border: #2a2a2a;
  --black-hover: #222222;
  --yellow: #FFD600;
  --yellow-dark: #E6C000;
  --yellow-soft: rgba(255, 214, 0, 0.12);
  --yellow-border: rgba(255, 214, 0, 0.3);
  --white: #ffffff;
  --white-80: rgba(255, 255, 255, 0.8);
  --white-40: rgba(255, 255, 255, 0.4);
  --white-10: rgba(255, 255, 255, 0.06);
  --success: #22c55e;
  --error: #ef4444;
  --radius: 12px;
  --radius-sm: 6px;
  --mono: 'JetBrains Mono', 'Courier New', monospace;
  --sans: 'Inter', system-ui, sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--black);
  color: var(--white);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.6;
  min-height: 100vh;
}

/* ---- SCROLLBAR ---- */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--black); }
::-webkit-scrollbar-thumb { background: var(--black-border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--yellow); }

/* ---- UTILITIES ---- */
.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.accent { color: var(--yellow); }

.mono { font-family: var(--mono); }

/* ============================================
   HEADER
   ============================================ */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 10, 10, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--black-border);
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-block {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: var(--yellow);
  border-radius: 8px;
  display: grid;
  place-items: center;
  font-size: 1.2rem;
}

.logo-text {
  display: flex;
  flex-direction: column;
}

.logo-main {
  font-family: var(--mono);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--yellow);
  line-height: 1;
}

.logo-sub {
  font-size: 0.65rem;
  color: var(--white-40);
  letter-spacing: 0.03em;
}

.header-nav {
  display: flex;
  gap: 1.5rem;
}

.nav-link {
  color: var(--white-80);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: color 0.2s;
}

.nav-link:hover {
  color: var(--yellow);
}

/* ============================================
   HERO
   ============================================ */
.hero {
  position: relative;
  padding: 5rem 1.5rem 4rem;
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 3rem;
  overflow: hidden;
}

.hero-inner {
  flex: 1;
  min-width: 0;
}

.hero-badge {
  display: inline-block;
  background: var(--yellow-soft);
  border: 1px solid var(--yellow-border);
  color: var(--yellow);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.35rem 0.9rem;
  border-radius: 100px;
  margin-bottom: 1.25rem;
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 3.8rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
}

.hero-desc {
  color: var(--white-80);
  font-size: 1rem;
  max-width: 480px;
  margin-bottom: 2.5rem;
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.stat {
  display: flex;
  flex-direction: column;
}

.stat-num {
  font-family: var(--mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--yellow);
  line-height: 1;
}

.stat-lbl {
  font-size: 0.72rem;
  color: var(--white-40);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-top: 0.2rem;
}

.stat-divider {
  width: 1px;
  height: 36px;
  background: var(--black-border);
}

/* Hero decoration */
.hero-decoration {
  flex-shrink: 0;
  width: 200px;
  height: 200px;
  display: none;
}

@media (min-width: 640px) {
  .hero-decoration { display: block; }
}

.deco-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
  padding: 1rem;
}

.bit-float {
  width: 40px;
  height: 40px;
  background: var(--black-card);
  border: 1px solid var(--black-border);
  border-radius: var(--radius-sm);
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 1rem;
  animation: floatBit 3s ease-in-out infinite;
  color: var(--white-40);
}

.bit-float.b1 { animation-delay: 0s; color: var(--yellow); border-color: var(--yellow-border); }
.bit-float.b2 { animation-delay: 0.2s; }
.bit-float.b3 { animation-delay: 0.4s; color: var(--yellow); border-color: var(--yellow-border); }
.bit-float.b4 { animation-delay: 0.6s; color: var(--yellow); border-color: var(--yellow-border); }
.bit-float.b5 { animation-delay: 0.8s; }
.bit-float.b6 { animation-delay: 1.0s; }
.bit-float.b7 { animation-delay: 1.2s; color: var(--yellow); border-color: var(--yellow-border); }
.bit-float.b8 { animation-delay: 1.4s; }

@keyframes floatBit {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}

/* ============================================
   MAIN AREA
   ============================================ */
.main {
  padding: 0 0 4rem;
}

/* ============================================
   CARD
   ============================================ */
.card {
  background: var(--black-card);
  border: 1px solid var(--black-border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 1.5rem;
}

.card-header {
  padding: 1.5rem 1.75rem 0;
  border-bottom: 1px solid var(--black-border);
  padding-bottom: 1.25rem;
}

.card-badge {
  display: inline-block;
  background: var(--yellow);
  color: var(--black);
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  margin-bottom: 0.5rem;
}

.card-badge.success {
  background: var(--success);
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--white);
}

.card-body {
  padding: 1.75rem;
}

/* ============================================
   FORM
   ============================================ */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.75rem;
}

@media (max-width: 600px) {
  .form-grid { grid-template-columns: 1fr; }
}

.form-group:nth-child(3) {
  grid-column: 1 / -1;
}

.form-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--white-80);
  margin-bottom: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.label-num {
  font-family: var(--mono);
  color: var(--yellow);
  font-size: 0.75rem;
}

.label-hint {
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  color: var(--white-40);
  font-size: 0.75rem;
}

.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.form-input {
  width: 100%;
  background: var(--black-soft);
  border: 1px solid var(--black-border);
  border-radius: var(--radius-sm);
  color: var(--white);
  font-size: 1.2rem;
  font-family: var(--mono);
  letter-spacing: 0.25em;
  padding: 0.75rem 3.5rem 0.75rem 1rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.form-input:focus {
  border-color: var(--yellow);
  box-shadow: 0 0 0 2px var(--yellow-soft);
}

.form-input::placeholder {
  color: var(--white-10);
  letter-spacing: 0.2em;
}

.form-input.error {
  border-color: var(--error);
  box-shadow: 0 0 0 2px rgba(239,68,68,0.15);
}

.input-badge {
  position: absolute;
  right: 0.75rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--white-40);
  background: var(--black-border);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
}

.bit-preview {
  display: flex;
  gap: 4px;
  margin-top: 0.6rem;
  flex-wrap: wrap;
  min-height: 28px;
}

.bit-preview .bp {
  width: 26px;
  height: 26px;
  border-radius: 4px;
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 700;
  border: 1px solid var(--black-border);
  background: var(--black-soft);
  color: var(--white-40);
  transition: all 0.15s;
}

.bit-preview .bp.one {
  background: var(--yellow-soft);
  border-color: var(--yellow-border);
  color: var(--yellow);
}

/* ============================================
   MODE SELECTOR
   ============================================ */
.mode-selector {
  display: flex;
  gap: 0.75rem;
}

.mode-option {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.9rem 1.25rem;
  border: 1px solid var(--black-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s;
  background: var(--black-soft);
}

.mode-option:hover {
  border-color: var(--yellow-border);
  background: var(--yellow-soft);
}

.mode-option.active {
  border-color: var(--yellow);
  background: var(--yellow-soft);
}

.mode-icon { font-size: 1.2rem; }

.mode-text {
  font-weight: 600;
  font-size: 0.9rem;
}

/* ============================================
   BUTTONS
   ============================================ */
.form-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.8rem 1.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  cursor: pointer;
  border: none;
  outline: none;
  transition: all 0.2s;
  text-transform: uppercase;
}

.btn-primary {
  background: var(--yellow);
  color: var(--black);
}

.btn-primary:hover {
  background: var(--yellow-dark);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: transparent;
  color: var(--white-80);
  border: 1px solid var(--black-border);
}

.btn-secondary:hover {
  border-color: var(--white-40);
  color: var(--white);
}

.btn-icon {
  font-size: 1rem;
}

/* ============================================
   ERROR
   ============================================ */
.error-msg {
  margin-top: 1rem;
  padding: 0.75rem 1rem;
  background: rgba(239,68,68,0.1);
  border: 1px solid rgba(239,68,68,0.3);
  border-radius: var(--radius-sm);
  color: #fca5a5;
  font-size: 0.875rem;
}

/* ============================================
   RESULT CARD
   ============================================ */
.result-row {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
}

.result-item {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.result-lbl {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--white-40);
}

.result-arrow {
  font-size: 1.5rem;
  color: var(--yellow);
  font-weight: 700;
}

.result-hex {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

/* ============================================
   BIT BOXES
   ============================================ */
.bit-boxes {
  display: flex;
  gap: 5px;
  flex-wrap: wrap;
}

.bit-box {
  width: 36px;
  height: 36px;
  border-radius: 6px;
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-size: 1rem;
  font-weight: 700;
  border: 1.5px solid var(--black-border);
  background: var(--black-soft);
  color: var(--white-40);
  position: relative;
}

.bit-box.one {
  background: var(--yellow-soft);
  border-color: var(--yellow);
  color: var(--yellow);
}

.bit-box.result-bit {
  width: 42px;
  height: 42px;
  font-size: 1.1rem;
}

.bit-box.result-bit.one {
  background: var(--yellow);
  color: var(--black);
  border-color: var(--yellow);
}

.bit-box .bit-idx {
  position: absolute;
  bottom: 1px;
  right: 3px;
  font-size: 0.45rem;
  color: var(--white-10);
  font-family: var(--mono);
}

/* ============================================
   STEPS TOGGLE
   ============================================ */
.steps-toggle {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1.1rem 1.5rem;
  background: var(--black-card);
  border: 1px solid var(--black-border);
  border-radius: var(--radius);
  cursor: pointer;
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 1rem;
  transition: all 0.2s;
  user-select: none;
}

.steps-toggle:hover {
  border-color: var(--yellow-border);
  background: var(--yellow-soft);
  color: var(--yellow);
}

.toggle-icon {
  color: var(--yellow);
  font-size: 0.8rem;
  transition: transform 0.3s;
}

.toggle-icon.open {
  transform: rotate(180deg);
}

/* ============================================
   STEPS CONTENT
   ============================================ */
.steps-content {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.section-block {
  background: var(--black-card);
  border: 1px solid var(--black-border);
  border-radius: var(--radius);
  overflow: hidden;
}

.section-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--black-border);
  background: var(--black-soft);
}

.section-num {
  width: 36px;
  height: 36px;
  background: var(--yellow);
  color: var(--black);
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 1rem;
  flex-shrink: 0;
}

.section-header h3 {
  font-size: 1.05rem;
  font-weight: 600;
}

/* ============================================
   STEP ITEM
   ============================================ */
.step-item {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--black-border);
}

.step-item:last-child {
  border-bottom: none;
}

.step-label {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 0.85rem;
}

.step-num-badge {
  font-family: var(--mono);
  font-size: 0.65rem;
  background: var(--yellow);
  color: var(--black);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  font-weight: 700;
}

.step-name {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--white);
}

.step-desc {
  font-size: 0.78rem;
  color: var(--white-40);
  margin-left: auto;
}

.step-body {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.step-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.step-row-label {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--white-40);
  min-width: 110px;
  flex-shrink: 0;
}

.step-op {
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--yellow);
  font-weight: 700;
  padding: 0 0.3rem;
}

.step-comment {
  font-size: 0.75rem;
  color: var(--white-40);
  font-style: italic;
  padding: 0.4rem 0.8rem;
  background: var(--white-10);
  border-radius: 4px;
  border-left: 2px solid var(--yellow);
  margin-top: 0.4rem;
}

/* ============================================
   TABLE (S-Box)
   ============================================ */
.sbox-table {
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: 0.8rem;
  margin-top: 0.5rem;
}

.sbox-table th, .sbox-table td {
  border: 1px solid var(--black-border);
  padding: 0.35rem 0.65rem;
  text-align: center;
}

.sbox-table th {
  background: var(--black-soft);
  color: var(--white-40);
  font-weight: 600;
}

.sbox-table td.highlight {
  background: var(--yellow);
  color: var(--black);
  font-weight: 700;
}

.sbox-result {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.3rem 0.75rem;
  background: var(--yellow-soft);
  border: 1px solid var(--yellow-border);
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--yellow);
  margin-top: 0.5rem;
}

/* ============================================
   ROUND HEADER
   ============================================ */
.round-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.5rem;
  background: var(--yellow-soft);
  border-bottom: 1px solid var(--yellow-border);
}

.round-badge {
  background: var(--yellow);
  color: var(--black);
  font-family: var(--mono);
  font-weight: 700;
  font-size: 0.75rem;
  padding: 0.2rem 0.65rem;
  border-radius: 4px;
}

.round-header h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--white);
}

/* ============================================
   ABOUT SECTION
   ============================================ */
.about-section {
  background: var(--black-soft);
  border-top: 1px solid var(--black-border);
  border-bottom: 1px solid var(--black-border);
  padding: 4rem 1.5rem;
}

.about-grid {
  max-width: 960px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}

@media (max-width: 600px) {
  .about-grid { grid-template-columns: 1fr; }
}

.about-title {
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.about-desc {
  color: var(--white-80);
  font-size: 0.925rem;
  line-height: 1.7;
}

.about-features {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.feature-item {
  display: flex;
  gap: 1rem;
  padding: 1rem;
  background: var(--black-card);
  border: 1px solid var(--black-border);
  border-radius: var(--radius-sm);
}

.feature-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
}

.feature-item strong {
  display: block;
  font-size: 0.9rem;
  margin-bottom: 0.25rem;
  color: var(--yellow);
}

.feature-item p {
  font-size: 0.8rem;
  color: var(--white-80);
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--white-40);
  font-size: 0.8rem;
}

/* ============================================
   ANIMATIONS
   ============================================ */
@keyframes slideDown {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.animate-in {
  animation: slideDown 0.3s ease forwards;
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 480px) {
  .hero { padding: 3rem 1.5rem 2.5rem; }
  .hero-title { font-size: 2.2rem; }
  .hero-stats { gap: 1.25rem; }
  .form-actions { flex-direction: column; }
  .btn { justify-content: center; }
  .result-row { flex-direction: column; align-items: flex-start; }
  .result-arrow { transform: rotate(90deg); }
  .mode-selector { flex-direction: column; }
  .step-row-label { min-width: 80px; }
}

/* Small bit boxes for steps */
.bit-boxes-sm .bit-box {
  width: 28px;
  height: 28px;
  font-size: 0.82rem;
}

/* Index label display */
.perm-table {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-top: 0.5rem;
}

.perm-row {
  display: flex;
  gap: 4px;
  align-items: center;
}

.perm-idx {
  font-family: var(--mono);
  font-size: 0.62rem;
  color: var(--white-40);
  min-width: 18px;
  text-align: center;
}