/* =========================================================
   S-DES Simulator — Stylesheet
   Theme: digital signal / circuit board, monospace bits
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;500;600;700&family=Inter:wght@400;500;600;700;800&display=swap');

:root {
  --bg: #14181f;
  --surface: #1d232e;
  --surface-raised: #242b38;
  --border: #313a4a;
  --text: #e7eaee;
  --text-muted: #8993a4;
  --accent: #5eead4;
  --accent-soft: rgba(94, 234, 212, 0.12);
  --amber: #fbbf24;
  --amber-soft: rgba(251, 191, 36, 0.12);
  --error: #f87171;

  --font-display: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --radius: 10px;
  --max-width: 760px;
}

* { box-sizing: border-box; }

html { color-scheme: dark; }

body {
  margin: 0;
  background: var(--bg);
  background-image:
    radial-gradient(circle at 15% 0%, rgba(94, 234, 212, 0.06), transparent 40%),
    radial-gradient(circle at 85% 100%, rgba(251, 191, 36, 0.05), transparent 40%);
  color: var(--text);
  font-family: var(--font-display);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.page {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 32px 20px 64px;
}

/* ---------- Hero ---------- */
.hero {
  text-align: center;
  padding: 40px 0 36px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 32px;
}

.hero__eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
}

.hero__title {
  font-family: var(--font-mono);
  font-size: clamp(2.5rem, 9vw, 4rem);
  font-weight: 700;
  letter-spacing: 0.05em;
  margin: 0 0 12px;
  color: var(--text);
}

.hero__cursor {
  color: var(--accent);
  animation: blink 1.1s steps(1) infinite;
}

@keyframes blink {
  50% { opacity: 0; }
}

.hero__subtitle {
  max-width: 480px;
  margin: 0 auto;
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* ---------- Card ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
}

.card__title {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.05rem;
  font-weight: 700;
  margin: 0 0 20px;
  color: var(--text);
}

.card__index {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 6px;
  padding: 3px 8px;
  flex-shrink: 0;
}

/* ---------- Form ---------- */
.field {
  margin-bottom: 18px;
}

.field label,
.field__label-static {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text);
}

.field input[type="text"] {
  width: 100%;
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  letter-spacing: 0.15em;
  color: var(--text);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.field input[type="text"]:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.field__hint {
  display: block;
  margin-top: 6px;
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* Mode toggle */
.mode-toggle {
  display: flex;
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 4px;
  gap: 4px;
}

.mode-toggle input[type="radio"] {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.mode-toggle label {
  flex: 1;
  text-align: center;
  padding: 10px 12px;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--text-muted);
  transition: background 0.15s ease, color 0.15s ease;
  margin: 0;
}

.mode-toggle input[type="radio"]:checked + label {
  background: var(--accent-soft);
  color: var(--accent);
}

.mode-toggle input[type="radio"]:focus-visible + label {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Buttons */
.actions {
  display: flex;
  gap: 12px;
  margin-top: 24px;
}

.btn {
  font-family: var(--font-display);
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  border-radius: 8px;
  padding: 12px 22px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.1s ease, opacity 0.15s ease, background 0.15s ease;
}

.btn:active { transform: scale(0.98); }

.btn--primary {
  background: var(--accent);
  color: #0b1017;
  flex: 1;
}

.btn--primary:hover { opacity: 0.88; }

.btn--ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text-muted);
}

.btn--ghost:hover {
  border-color: var(--text-muted);
  color: var(--text);
}

.btn--toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: var(--surface-raised);
  border: 1px solid var(--border);
  color: var(--accent);
  margin-top: 22px;
  padding: 13px;
}

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

.btn--toggle svg {
  transition: transform 0.2s ease;
}

.btn--toggle[aria-expanded="true"] svg {
  transform: rotate(180deg);
}

.error-msg {
  color: var(--error);
  font-size: 0.85rem;
  margin: 14px 0 0;
  font-weight: 600;
}

.error-msg:empty { display: none; }

/* ---------- Bit grid (kotak bit bernomor) ---------- */
.bitgrid {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.bitcell {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.bitcell__value {
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 700;
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
}

.bitcell__index {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.bitgrid--small .bitcell__value {
  width: 30px;
  height: 30px;
  font-size: 0.95rem;
}

.bitgrid--accent .bitcell__value {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}

.bitgrid--amber .bitcell__value {
  border-color: var(--amber);
  color: var(--amber);
  background: var(--amber-soft);
}

/* ---------- Result section ---------- */
.result-summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.result-summary__item {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.result-summary__label {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  font-weight: 600;
}

.result-summary__arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
}

.result-keys {
  display: flex;
  gap: 28px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}

.result-keys__item {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.result-keys__label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  font-weight: 600;
}

/* ---------- Solution steps ---------- */
.step {
  margin-bottom: 22px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--border);
}

.step:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.step__label {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 4px;
}

.step__desc {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.step__row {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 10px;
}

.step__row:last-child { margin-bottom: 0; }

.step__row-label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.step__op {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--amber);
  font-weight: 700;
}

.step__sbox-table {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  border-collapse: collapse;
  margin-top: 8px;
}

.step__sbox-table th,
.step__sbox-table td {
  border: 1px solid var(--border);
  padding: 5px 9px;
  text-align: center;
  color: var(--text-muted);
}

.step__sbox-table th {
  color: var(--text);
  background: var(--surface-raised);
}

.step__sbox-table td.active {
  color: var(--amber);
  background: var(--amber-soft);
  font-weight: 700;
  border-color: var(--amber);
}

/* ---------- Footer ---------- */
.footer {
  text-align: center;
  margin-top: 40px;
  color: var(--text-muted);
  font-size: 0.78rem;
  font-family: var(--font-mono);
}

/* ---------- Responsive ---------- */
@media (max-width: 480px) {
  .card { padding: 18px; }
  .actions { flex-direction: column; }
  .result-summary { justify-content: center; }
  .result-summary__arrow { transform: rotate(90deg); }
  .bitcell__value { width: 32px; height: 32px; font-size: 0.95rem; }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  .hero__cursor { animation: none; }
  * { transition: none !important; }
}