/* ═══════════════════════════════════════════════════════
   HILL CIPHER SIMULATOR — Dark Cybersecurity Theme
   ═══════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500;600;700&display=swap');

:root {
  --bg-primary: #06080d;
  --bg-secondary: #0c1017;
  --bg-card: #0f1520;
  --bg-card-hover: #141c2a;
  --bg-input: #0a0f18;
  --border: #1a2535;
  --border-focus: #00d4ff55;
  --neon-blue: #00d4ff;
  --neon-blue-dim: #00d4ff88;
  --neon-green: #00ff41;
  --neon-green-dim: #00ff4188;
  --neon-orange: #ff8c00;
  --neon-purple: #a855f7;
  --neon-red: #ff3355;
  --text-primary: #e8edf5;
  --text-secondary: #7a8ba8;
  --text-muted: #4a5568;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow-glow-blue: 0 0 20px #00d4ff22, 0 0 40px #00d4ff11;
  --shadow-glow-green: 0 0 20px #00ff4122;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  line-height: 1.6;
}

/* ─── BACKGROUND EFFECTS ───────────────────────────────── */
.bg-grid {
  position: fixed; inset: 0; z-index: 0; pointer-events: none;
  background-image:
    linear-gradient(rgba(0,212,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,212,255,0.03) 1px, transparent 1px);
  background-size: 60px 60px;
}

.bg-glow {
  position: fixed; z-index: 0; pointer-events: none;
  width: 600px; height: 600px; border-radius: 50%;
  filter: blur(150px); opacity: 0.15;
}
.bg-glow--blue { top: -200px; right: -100px; background: var(--neon-blue); }
.bg-glow--green { bottom: -200px; left: -100px; background: var(--neon-green); }

/* ─── APP CONTAINER ────────────────────────────────────── */
.app { position: relative; z-index: 1; max-width: 1280px; margin: 0 auto; padding: 20px; }

/* ─── HEADER ───────────────────────────────────────────── */
.header {
  text-align: center; padding: 32px 20px 24px;
  border-bottom: 1px solid var(--border); margin-bottom: 24px;
}
.header__icon {
  font-size: 2.5rem; margin-bottom: 8px;
  filter: drop-shadow(0 0 12px var(--neon-blue));
}
.header__title {
  font-size: 2rem; font-weight: 700;
  background: linear-gradient(135deg, var(--neon-blue), var(--neon-green));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.header__subtitle {
  font-size: 0.9rem; color: var(--text-secondary); margin-top: 4px;
  font-family: var(--font-mono); letter-spacing: 2px; text-transform: uppercase;
}

/* ─── TAB NAVIGATION ───────────────────────────────────── */
.tabs {
  display: flex; gap: 4px; justify-content: center;
  background: var(--bg-secondary); border-radius: var(--radius);
  padding: 4px; border: 1px solid var(--border); margin-bottom: 24px;
  flex-wrap: wrap;
}
.tab-btn {
  flex: 1; min-width: 120px; padding: 12px 20px;
  background: transparent; border: none; border-radius: var(--radius-sm);
  color: var(--text-secondary); font-family: var(--font-body);
  font-size: 0.85rem; font-weight: 500; cursor: pointer;
  transition: var(--transition); display: flex; align-items: center;
  justify-content: center; gap: 8px;
}
.tab-btn:hover { color: var(--text-primary); background: var(--bg-card); }
.tab-btn.active {
  background: var(--bg-card); color: var(--neon-blue);
  box-shadow: var(--shadow-glow-blue);
  border: 1px solid var(--border-focus);
}
.tab-btn__icon { font-size: 1.1rem; }

/* ─── TAB CONTENT ──────────────────────────────────────── */
.tab-content { display: none; animation: fadeIn 0.4s ease; }
.tab-content.active { display: block; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ─── PANELS ───────────────────────────────────────────── */
.panel-grid {
  display: grid; grid-template-columns: 380px 1fr; gap: 20px;
}
@media (max-width: 900px) {
  .panel-grid { grid-template-columns: 1fr; }
}

.panel {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px;
}
.panel--sticky { position: sticky; top: 20px; align-self: start; }
.panel__title {
  font-size: 1rem; font-weight: 600; margin-bottom: 16px;
  display: flex; align-items: center; gap: 8px; color: var(--neon-blue);
  font-family: var(--font-mono); text-transform: uppercase; letter-spacing: 1px;
  font-size: 0.8rem;
}
.panel__title::before {
  content: ''; display: block; width: 3px; height: 18px;
  background: var(--neon-blue); border-radius: 2px;
}

/* ─── FORM ELEMENTS ────────────────────────────────────── */
.form-group { margin-bottom: 16px; }
.form-label {
  display: block; font-size: 0.8rem; font-weight: 500;
  color: var(--text-secondary); margin-bottom: 6px;
  font-family: var(--font-mono); text-transform: uppercase; letter-spacing: 0.5px;
}
.form-input {
  width: 100%; padding: 12px 14px;
  background: var(--bg-input); border: 1px solid var(--border);
  border-radius: var(--radius-sm); color: var(--text-primary);
  font-family: var(--font-mono); font-size: 0.95rem;
  transition: var(--transition); outline: none;
}
.form-input:focus {
  border-color: var(--neon-blue);
  box-shadow: 0 0 0 3px #00d4ff15;
}
.form-input::placeholder { color: var(--text-muted); }

/* ─── MATRIX INPUT ─────────────────────────────────────── */
.matrix-size-toggle {
  display: flex; gap: 4px; margin-bottom: 12px;
  background: var(--bg-input); padding: 3px; border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}
.size-btn {
  flex: 1; padding: 8px; background: transparent; border: none;
  border-radius: 6px; color: var(--text-secondary);
  font-family: var(--font-mono); font-size: 0.8rem; font-weight: 600;
  cursor: pointer; transition: var(--transition);
}
.size-btn.active {
  background: var(--neon-blue); color: var(--bg-primary);
}

.matrix-container {
  display: flex; align-items: center; justify-content: center;
  gap: 0; margin: 12px 0;
}
.matrix-bracket {
  font-size: 3rem; color: var(--neon-blue); font-weight: 100;
  line-height: 1; user-select: none; opacity: 0.7;
  font-family: var(--font-mono);
}
.matrix-grid {
  display: grid; gap: 6px; padding: 8px;
}
.matrix-grid.size-2 { grid-template-columns: repeat(2, 1fr); }
.matrix-grid.size-3 { grid-template-columns: repeat(3, 1fr); }

.matrix-cell {
  width: 56px; height: 48px; text-align: center;
  background: var(--bg-input); border: 1px solid var(--border);
  border-radius: 6px; color: var(--text-primary);
  font-family: var(--font-mono); font-size: 1rem; font-weight: 600;
  transition: var(--transition); outline: none;
}
.matrix-cell:focus {
  border-color: var(--neon-blue);
  box-shadow: 0 0 0 3px #00d4ff15;
}

/* ─── BUTTONS ──────────────────────────────────────────── */
.btn-group { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }

.btn {
  padding: 10px 18px; border: none; border-radius: var(--radius-sm);
  font-family: var(--font-body); font-size: 0.85rem; font-weight: 600;
  cursor: pointer; transition: var(--transition);
  display: inline-flex; align-items: center; gap: 6px;
}
.btn--primary {
  background: linear-gradient(135deg, var(--neon-blue), #0099cc);
  color: #fff; flex: 1;
}
.btn--primary:hover {
  box-shadow: 0 0 20px #00d4ff44; transform: translateY(-1px);
}
.btn--secondary {
  background: var(--bg-input); color: var(--text-secondary);
  border: 1px solid var(--border);
}
.btn--secondary:hover {
  border-color: var(--neon-blue); color: var(--neon-blue);
}
.btn--success {
  background: linear-gradient(135deg, var(--neon-green), #00cc33);
  color: #000;
}
.btn--success:hover { box-shadow: 0 0 20px #00ff4144; }
.btn--danger {
  background: transparent; color: var(--neon-red);
  border: 1px solid var(--neon-red);
}
.btn--danger:hover { background: #ff335515; }
.btn--small { padding: 6px 12px; font-size: 0.75rem; }
.btn--icon { padding: 10px; min-width: 40px; justify-content: center; }

/* ─── STEP DISPLAY ─────────────────────────────────────── */
.steps-container { display: flex; flex-direction: column; gap: 16px; }

.step-card {
  background: var(--bg-secondary); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px;
  animation: stepReveal 0.5s ease forwards;
  opacity: 0; transform: translateX(-20px);
  border-left: 3px solid var(--neon-blue);
}
.step-card:nth-child(even) { border-left-color: var(--neon-green); }

@keyframes stepReveal {
  to { opacity: 1; transform: translateX(0); }
}

.step-card__number {
  display: inline-flex; align-items: center; justify-content: center;
  width: 28px; height: 28px; border-radius: 50%;
  background: var(--neon-blue); color: var(--bg-primary);
  font-family: var(--font-mono); font-size: 0.75rem; font-weight: 700;
  margin-right: 10px;
}
.step-card:nth-child(even) .step-card__number { background: var(--neon-green); }

.step-card__title {
  font-weight: 600; font-size: 0.95rem; display: inline;
}
.step-card__desc {
  color: var(--text-secondary); font-size: 0.85rem; margin: 8px 0 12px;
}

/* ─── MATRIX DISPLAY (Read-only) ──────────────────────── */
.matrix-display {
  display: inline-flex; align-items: center; gap: 0; margin: 8px 4px;
  vertical-align: middle;
}
.matrix-display__bracket {
  font-size: 2.2rem; font-weight: 100; line-height: 1;
  font-family: var(--font-mono); opacity: 0.6;
}
.matrix-display__grid {
  display: grid; gap: 2px; padding: 4px 8px;
}
.matrix-display__grid.cols-2 { grid-template-columns: repeat(2, 1fr); }
.matrix-display__grid.cols-3 { grid-template-columns: repeat(3, 1fr); }

.matrix-display__cell {
  padding: 6px 10px; text-align: center;
  font-family: var(--font-mono); font-size: 0.9rem; font-weight: 600;
  border-radius: 4px; min-width: 36px;
}
.matrix-display--key .matrix-display__cell {
  background: #00d4ff15; color: var(--neon-blue);
}
.matrix-display--key .matrix-display__bracket { color: var(--neon-blue); }
.matrix-display--plain .matrix-display__cell {
  background: #00ff4115; color: var(--neon-green);
}
.matrix-display--plain .matrix-display__bracket { color: var(--neon-green); }
.matrix-display--cipher .matrix-display__cell {
  background: #ff8c0015; color: var(--neon-orange);
}
.matrix-display--cipher .matrix-display__bracket { color: var(--neon-orange); }
.matrix-display--inverse .matrix-display__cell {
  background: #a855f715; color: var(--neon-purple);
}
.matrix-display--inverse .matrix-display__bracket { color: var(--neon-purple); }

/* ─── CONVERSION TABLE ─────────────────────────────────── */
.conv-table {
  display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0;
}
.conv-item {
  display: flex; flex-direction: column; align-items: center;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 6px; padding: 6px 10px; min-width: 40px;
}
.conv-item__char {
  font-family: var(--font-mono); font-weight: 700; font-size: 1rem;
}
.conv-item__arrow { color: var(--text-muted); font-size: 0.7rem; }
.conv-item__num {
  font-family: var(--font-mono); font-weight: 600; font-size: 0.85rem;
  color: var(--neon-blue);
}
.conv-item--green .conv-item__char { color: var(--neon-green); }
.conv-item--green .conv-item__num { color: var(--neon-green); }
.conv-item--orange .conv-item__char { color: var(--neon-orange); }
.conv-item--orange .conv-item__num { color: var(--neon-orange); }

/* ─── BLOCK DISPLAY ────────────────────────────────────── */
.blocks-row { display: flex; flex-wrap: wrap; gap: 8px; margin: 8px 0; }
.block-chip {
  display: flex; gap: 4px; padding: 6px 12px;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 6px; font-family: var(--font-mono); font-size: 0.9rem;
}
.block-chip__label {
  color: var(--text-muted); font-size: 0.7rem; margin-right: 4px;
}

/* ─── CALCULATION LINE ─────────────────────────────────── */
.calc-line {
  font-family: var(--font-mono); font-size: 0.85rem;
  padding: 4px 0; color: var(--text-secondary);
}
.calc-line strong { color: var(--text-primary); }
.calc-highlight { color: var(--neon-blue); font-weight: 600; }
.calc-highlight--green { color: var(--neon-green); }
.calc-highlight--orange { color: var(--neon-orange); }
.calc-highlight--purple { color: var(--neon-purple); }

/* ─── RESULT BOX ───────────────────────────────────────── */
.result-box {
  background: linear-gradient(135deg, #00d4ff08, #00ff4108);
  border: 1px solid #00d4ff33; border-radius: var(--radius);
  padding: 20px; text-align: center; margin-top: 16px;
}
.result-box__label {
  font-size: 0.75rem; font-family: var(--font-mono);
  text-transform: uppercase; letter-spacing: 2px;
  color: var(--text-secondary); margin-bottom: 8px;
}
.result-box__text {
  font-size: 1.8rem; font-family: var(--font-mono); font-weight: 700;
  letter-spacing: 6px;
}
.result-box__text--cipher { color: var(--neon-orange); }
.result-box__text--plain { color: var(--neon-green); }
.result-box__actions { display: flex; justify-content: center; gap: 8px; margin-top: 12px; }

/* ─── FORMULA DISPLAY ──────────────────────────────────── */
.formula {
  background: var(--bg-input); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 16px 20px;
  font-family: var(--font-mono); font-size: 0.95rem;
  text-align: center; margin: 12px 0; color: var(--neon-blue);
  letter-spacing: 1px;
}

/* ─── EDUCATION TAB ────────────────────────────────────── */
.edu-section { margin-bottom: 32px; }
.edu-section__title {
  font-size: 1.15rem; font-weight: 700; margin-bottom: 12px;
  color: var(--neon-blue); display: flex; align-items: center; gap: 10px;
}
.edu-section__title::before {
  content: ''; width: 4px; height: 22px;
  background: linear-gradient(var(--neon-blue), var(--neon-green));
  border-radius: 2px;
}
.edu-text {
  color: var(--text-secondary); font-size: 0.9rem; line-height: 1.8;
  margin-bottom: 12px;
}
.edu-text strong { color: var(--text-primary); }
.edu-list {
  list-style: none; padding: 0;
}
.edu-list li {
  padding: 6px 0 6px 20px; color: var(--text-secondary);
  font-size: 0.9rem; position: relative;
}
.edu-list li::before {
  content: '▸'; position: absolute; left: 0; color: var(--neon-blue);
}

/* ─── HISTORY TAB ──────────────────────────────────────── */
.history-list { display: flex; flex-direction: column; gap: 12px; }
.history-item {
  background: var(--bg-secondary); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px;
  cursor: pointer; transition: var(--transition);
}
.history-item:hover {
  border-color: var(--neon-blue); background: var(--bg-card-hover);
}
.history-item__header {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: 8px;
}
.history-item__type {
  font-family: var(--font-mono); font-size: 0.75rem; font-weight: 600;
  text-transform: uppercase; letter-spacing: 1px; padding: 3px 10px;
  border-radius: 4px;
}
.history-item__type--encrypt {
  background: #00d4ff20; color: var(--neon-blue);
}
.history-item__type--decrypt {
  background: #00ff4120; color: var(--neon-green);
}
.history-item__time {
  font-size: 0.75rem; color: var(--text-muted); font-family: var(--font-mono);
}
.history-item__content {
  font-family: var(--font-mono); font-size: 0.85rem;
  display: flex; gap: 16px; flex-wrap: wrap;
}
.history-item__field { color: var(--text-secondary); }
.history-item__field strong { color: var(--text-primary); }

.empty-state {
  text-align: center; padding: 60px 20px; color: var(--text-muted);
}
.empty-state__icon { font-size: 3rem; margin-bottom: 12px; opacity: 0.3; }
.empty-state__text { font-size: 0.9rem; }

/* ─── TOAST NOTIFICATION ───────────────────────────────── */
.toast {
  position: fixed; bottom: 24px; right: 24px; z-index: 1000;
  padding: 14px 24px; border-radius: var(--radius-sm);
  background: var(--bg-card); border: 1px solid var(--neon-green);
  color: var(--neon-green); font-family: var(--font-mono); font-size: 0.85rem;
  box-shadow: var(--shadow-glow-green);
  animation: toastIn 0.3s ease, toastOut 0.3s ease 2.5s forwards;
}
@keyframes toastIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes toastOut {
  to { opacity: 0; transform: translateY(20px); }
}

/* ─── ERROR MESSAGE ────────────────────────────────────── */
.error-msg {
  background: #ff335515; border: 1px solid var(--neon-red);
  border-radius: var(--radius-sm); padding: 12px 16px;
  color: var(--neon-red); font-size: 0.85rem; margin: 12px 0;
  font-family: var(--font-mono); display: flex; align-items: center; gap: 8px;
}

/* ─── LOADING / PROCESSING ─────────────────────────────── */
.processing-bar {
  height: 3px; background: var(--bg-input); border-radius: 2px;
  overflow: hidden; margin: 16px 0;
}
.processing-bar__fill {
  height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--neon-blue), var(--neon-green));
  border-radius: 2px; transition: width 0.3s ease;
}

/* ─── SCROLLBAR ────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb {
  background: var(--border); border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* ─── RESPONSIVE ───────────────────────────────────────── */
@media (max-width: 600px) {
  .header__title { font-size: 1.4rem; }
  .panel { padding: 16px; }
  .matrix-cell { width: 48px; height: 42px; font-size: 0.9rem; }
  .result-box__text { font-size: 1.3rem; letter-spacing: 4px; }
  .tab-btn { min-width: 80px; padding: 10px 12px; font-size: 0.78rem; }
}

/* ─── UTILITY ──────────────────────────────────────────── */
.mt-sm { margin-top: 8px; }
.mt-md { margin-top: 16px; }
.mb-md { margin-bottom: 16px; }
.text-center { text-align: center; }
.text-mono { font-family: var(--font-mono); }
.text-blue { color: var(--neon-blue); }
.text-green { color: var(--neon-green); }
.text-orange { color: var(--neon-orange); }
.text-purple { color: var(--neon-purple); }
.flex-center { display: flex; align-items: center; justify-content: center; }
.gap-sm { gap: 8px; }
.hidden { display: none !important; }

.divider {
  border: none; border-top: 1px solid var(--border); margin: 20px 0;
}

.badge {
  display: inline-block; padding: 2px 8px; border-radius: 4px;
  font-family: var(--font-mono); font-size: 0.7rem; font-weight: 600;
}
.badge--blue { background: #00d4ff20; color: var(--neon-blue); }
.badge--green { background: #00ff4120; color: var(--neon-green); }