/* ============================================================
   ROT / Caesar Cipher PWA — style.css
   Aesthetic: Utilitarian Cipher Terminal
   Dark background (#0f172a), navy accents (#1e3a8a), amber (#f59e0b)
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Rajdhani:wght@400;500;600;700&family=Courier+Prime:wght@400;700&display=swap');

/* ── CSS Variables ────────────────────────────────────────── */
:root {
  --bg:           #0f172a;
  --bg-surface:   #111827;
  --bg-panel:     #0d1526;
  --navy:         #1e3a8a;
  --navy-mid:     #1d4ed8;
  --navy-light:   #2563eb;
  --amber:        #f59e0b;
  --amber-light:  #fbbf24;
  --amber-dim:    #b45309;
  --text:         #e2e8f0;
  --text-muted:   #94a3b8;
  --text-dim:     #475569;
  --border:       #1e3a8a44;
  --border-strong:#1e3a8a99;
  --green:        #22c55e;
  --green-dim:    #16a34a;
  --radius-sm:    3px;
  --radius:       6px;
  --radius-lg:    10px;
  --font-ui:      'Rajdhani', 'Segoe UI', sans-serif;
  --font-mono:    'Courier Prime', 'Courier New', monospace;
  --transition:   150ms cubic-bezier(0.4, 0, 0.2, 1);
  --glow-amber:   0 0 12px #f59e0b44;
  --glow-navy:    0 0 16px #1e3a8a66;
  --shadow-panel: 0 4px 24px #00000066, inset 0 1px 0 #ffffff08;
}

/* ── Reset & Base ─────────────────────────────────────────── */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  height: 100%;
  overflow: hidden;
}

body {
  background-color: var(--bg);
  color: var(--text);
  font-family: var(--font-ui);
  font-weight: 400;
  line-height: 1.5;
  height: 100dvh;
  overflow: hidden;
  display: flex;
  flex-direction: column;

  /* Subtle noise texture overlay via SVG data URI */
  background-image:
    radial-gradient(ellipse 80% 50% at 50% 0%, #1e3a8a18 0%, transparent 70%),
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='200' height='200' filter='url(%23n)' opacity='0.03'/%3E%3C/svg%3E");
}

/* ── Header ───────────────────────────────────────────────── */
header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 20px 32px 18px;
  border-bottom: 1px solid var(--border-strong);
  background: linear-gradient(180deg, #0d1526 0%, transparent 100%);
  position: relative;
  z-index: 10;
}

header::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--amber) 30%, var(--navy-mid) 70%, transparent);
  opacity: 0.5;
}

.icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-mid) 100%);
  border-radius: var(--radius);
  border: 1px solid var(--border-strong);
  font-size: 22px;
  box-shadow: var(--glow-navy);
  flex-shrink: 0;
}

h1 {
  font-family: var(--font-ui);
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text);
  line-height: 1;
}

h1 span {
  color: var(--amber);
}

/* Decorative grid marks in header */
header .header-meta {
  margin-left: auto;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  color: var(--text-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  user-select: none;
}

/* ── Main Layout ──────────────────────────────────────────── */
main {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
  gap: 0;
  padding: 20px 32px 16px;
  max-width: 1280px;
  width: 100%;
  margin: 0 auto;
  overflow: hidden;
}

/* ── Utility ──────────────────────────────────────────────── */
.hidden { display: none !important; }

/* ── Cipher Controls (outer wrapper) ─────────────────────── */
.cipher-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 20px;
}

/* Cipher type selector row */
.cipher-select-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 24px;
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-panel);
  position: relative;
  overflow: hidden;
}

.cipher-select-wrap::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--navy-mid) 0%, var(--navy-light) 100%);
  border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}

.cipher-select-wrap label {
  font-family: var(--font-ui);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-muted);
  white-space: nowrap;
  user-select: none;
}

#cipher-select {
  font-family: var(--font-ui);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  color: var(--text);
  background: var(--bg-panel);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 6px 32px 6px 12px;
  cursor: pointer;
  outline: none;
  -webkit-appearance: none;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%2394a3b8' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  transition: border-color var(--transition), box-shadow var(--transition);
}

#cipher-select:hover { border-color: var(--navy-light); }
#cipher-select:focus { border-color: var(--amber); box-shadow: 0 0 0 2px var(--amber)33; }
#cipher-select option { background: var(--bg-panel); color: var(--text); }

/* Vigenère key input row */
.vigenere-controls {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 24px;
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-panel);
  position: relative;
  overflow: hidden;
}

.vigenere-controls::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--amber-dim) 0%, var(--amber) 100%);
  border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}

.vigenere-controls label {
  font-family: var(--font-ui);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-muted);
  white-space: nowrap;
  user-select: none;
}

#vigenere-key {
  flex: 1;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--bg-panel);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 7px 12px;
  outline: none;
  caret-color: var(--amber);
  transition: border-color var(--transition), box-shadow var(--transition);
}

#vigenere-key::placeholder { color: var(--text-dim); font-style: italic; }
#vigenere-key:hover  { border-color: var(--navy-light); }
#vigenere-key:focus  { border-color: var(--amber); box-shadow: inset 0 0 0 1px var(--amber)55; }

/* ── Shift Controls ───────────────────────────────────────── */
.shift-controls {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 24px;
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-panel);
  flex-wrap: wrap;
  position: relative;
  overflow: hidden;
}

/* Decorative left stripe */
.shift-controls::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--amber) 0%, var(--amber-dim) 100%);
  border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}

.shift-label {
  font-family: var(--font-ui);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-muted);
  white-space: nowrap;
  user-select: none;
}

#shift-val {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--amber);
  min-width: 3ch;
  text-align: center;
  text-shadow: var(--glow-amber);
  line-height: 1;
  transition: color var(--transition), text-shadow var(--transition);
  user-select: none;
}

/* Range slider — cross-browser */
#shift-slider {
  flex: 1;
  min-width: 120px;
  -webkit-appearance: none;
  appearance: none;
  height: 4px;
  background: linear-gradient(90deg, var(--amber) calc(var(--pct, 50%) * 1%), var(--border-strong) calc(var(--pct, 50%) * 1%));
  border-radius: 2px;
  outline: none;
  cursor: pointer;
  transition: background var(--transition);
}

/* Webkit thumb */
#shift-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  background: var(--amber);
  border-radius: 50%;
  border: 2px solid var(--bg);
  box-shadow: 0 0 8px var(--amber), 0 2px 6px #00000080;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
}

#shift-slider::-webkit-slider-thumb:hover {
  background: var(--amber-light);
  transform: scale(1.15);
  box-shadow: 0 0 14px var(--amber), 0 2px 8px #00000080;
}

#shift-slider:focus::-webkit-slider-thumb {
  box-shadow: 0 0 0 3px var(--amber)44, 0 0 10px var(--amber);
}

/* Firefox thumb */
#shift-slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  background: var(--amber);
  border-radius: 50%;
  border: 2px solid var(--bg);
  box-shadow: 0 0 8px var(--amber), 0 2px 6px #00000080;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
}

#shift-slider::-moz-range-thumb:hover {
  background: var(--amber-light);
  transform: scale(1.15);
}

#shift-slider::-moz-range-track {
  height: 4px;
  background: var(--border-strong);
  border-radius: 2px;
}

/* ROT13 button */
#rot13-btn {
  font-family: var(--font-ui);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--bg);
  background: linear-gradient(135deg, var(--amber) 0%, var(--amber-light) 100%);
  border: none;
  border-radius: var(--radius);
  padding: 8px 18px;
  cursor: pointer;
  white-space: nowrap;
  box-shadow: 0 2px 8px #f59e0b55, inset 0 1px 0 #ffffff30;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  user-select: none;
}

#rot13-btn:hover {
  background: linear-gradient(135deg, var(--amber-light) 0%, var(--amber) 100%);
  transform: translateY(-1px);
  box-shadow: 0 4px 14px #f59e0b66, inset 0 1px 0 #ffffff40;
}

#rot13-btn:active {
  transform: translateY(0);
  box-shadow: 0 1px 4px #f59e0b44;
}

#rot13-btn:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 2px;
}

/* ── Panels Grid ──────────────────────────────────────────── */
.panels {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  flex: 1;
  min-height: 0;
}

/* ── Panel ────────────────────────────────────────────────── */
.panel {
  display: flex;
  flex-direction: column;
  background: var(--bg-panel);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  overflow: hidden;
  min-height: 0;
  box-shadow: var(--shadow-panel);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.panel:hover {
  border-color: var(--navy-light);
  box-shadow: var(--shadow-panel), var(--glow-navy);
}

/* Panel header */
.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px 8px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, #0d1a30 0%, transparent 100%);
}

.panel-label {
  font-family: var(--font-ui);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  user-select: none;
  display: flex;
  align-items: center;
  gap: 8px;
}

.panel-label::before {
  content: '';
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.panel-label.input {
  color: var(--navy-light);
}

.panel-label.input::before {
  background: var(--navy-light);
  box-shadow: 0 0 6px var(--navy-light);
}

.panel-label.output {
  color: var(--amber);
}

.panel-label.output::before {
  background: var(--amber);
  box-shadow: 0 0 6px var(--amber);
}

/* Textarea */
.panel textarea {
  flex: 1;
  min-height: 0;
  width: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 0.95rem;
  line-height: 1.65;
  border: none;
  outline: none;
  padding: 14px 16px;
  resize: none;
  overflow-y: auto;
  transition: box-shadow var(--transition), background var(--transition);
  caret-color: var(--amber);
}

.panel textarea::placeholder {
  color: var(--text-dim);
  font-style: italic;
}

.panel textarea:focus {
  background: #0a1020;
  box-shadow: inset 0 0 0 2px var(--amber)66, inset 0 0 20px #f59e0b0a;
}

/* Scrollbar styling */
.panel textarea::-webkit-scrollbar {
  width: 6px;
}

.panel textarea::-webkit-scrollbar-track {
  background: var(--bg-panel);
}

.panel textarea::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: 3px;
}

.panel textarea::-webkit-scrollbar-thumb:hover {
  background: var(--navy-mid);
}

/* Panel footer */
.panel-footer {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding: 10px 14px;
  border-top: 1px solid var(--border);
  background: linear-gradient(0deg, #0d1a30 0%, transparent 100%);
  gap: 10px;
}

/* Char count hint */
.panel-footer .char-count {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-dim);
  margin-right: auto;
  letter-spacing: 0.05em;
  user-select: none;
}

/* Copy button */
.copy-btn {
  font-family: var(--font-ui);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
  background: transparent;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 6px 14px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: color var(--transition), border-color var(--transition),
              background var(--transition), transform var(--transition),
              box-shadow var(--transition);
  user-select: none;
}

.copy-btn::before {
  content: '⎘';
  font-size: 0.9em;
  line-height: 1;
  transition: transform var(--transition);
}

.copy-btn:hover {
  color: var(--text);
  border-color: var(--navy-light);
  background: var(--navy)22;
  transform: translateY(-1px);
  box-shadow: 0 2px 8px #1e3a8a44;
}

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

.copy-btn:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 2px;
}

/* Copied state */
.copy-btn.copied {
  color: var(--green);
  border-color: var(--green-dim);
  background: #22c55e0f;
  box-shadow: 0 0 10px #22c55e33;
}

.copy-btn.copied::before {
  content: '✓';
  transform: scale(1.2);
}

/* ── Footer ───────────────────────────────────────────────── */
footer {
  text-align: center;
  padding: 14px 32px 18px;
  border-top: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  color: var(--text-dim);
  background: linear-gradient(0deg, #0d1526 0%, transparent 100%);
  user-select: none;
}

footer a {
  color: var(--navy-light);
  text-decoration: none;
  transition: color var(--transition);
}

footer a:hover {
  color: var(--amber);
}

/* ── Animations ───────────────────────────────────────────── */
@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulseAmber {
  0%, 100% { opacity: 1; }
  50%       { opacity: 0.6; }
}

/* Page load stagger */
header {
  animation: fadeSlideIn 0.4s ease both;
}

.cipher-controls {
  animation: fadeSlideIn 0.4s 0.1s ease both;
}

.panels .panel:nth-child(1) {
  animation: fadeSlideIn 0.4s 0.18s ease both;
}

.panels .panel:nth-child(2) {
  animation: fadeSlideIn 0.4s 0.26s ease both;
}

footer {
  animation: fadeSlideIn 0.4s 0.34s ease both;
}

/* Shift value pulse on change (triggered by JS adding .pulse class) */
#shift-val.pulse {
  animation: pulseAmber 0.3s ease;
}

/* ── PWA / Standalone ─────────────────────────────────────── */
@media (display-mode: standalone) {
  html {
    height: -webkit-fill-available;
  }

  body {
    height: 100dvh;
    padding-left: env(safe-area-inset-left);
    padding-right: env(safe-area-inset-right);
  }

  header {
    padding-top: max(16px, env(safe-area-inset-top));
  }

  footer {
    padding-bottom: max(14px, env(safe-area-inset-bottom));
  }
}

/* ── Responsive — Tablet ──────────────────────────────────── */
@media (max-width: 900px) {
  main {
    padding: 16px 20px 12px;
  }

  header {
    padding: 14px 20px 12px;
  }
}

/* ── Responsive — Mobile (< 640px) ───────────────────────── */
@media (max-width: 639px) {
  header {
    padding: 14px 16px 12px;
    gap: 10px;
  }

  h1 {
    font-size: 1.15rem;
    letter-spacing: 0.06em;
  }

  .icon {
    width: 36px;
    height: 36px;
    font-size: 18px;
  }

  .header-meta {
    display: none;
  }

  main {
    padding: 10px 12px 8px;
    gap: 0;
  }

  .cipher-controls {
    margin-bottom: 10px;
    gap: 6px;
  }

  .cipher-select-wrap,
  .vigenere-controls {
    padding: 8px 12px 8px 16px;
  }

  .shift-controls {
    padding: 8px 12px 8px 16px;
    gap: 8px;
  }

  #shift-val {
    font-size: 1.4rem;
  }

  #shift-slider {
    min-width: 80px;
  }

  #rot13-btn {
    padding: 8px 14px;
    font-size: 0.75rem;
  }

  /* Vertical stack */
  .panels {
    display: flex;
    flex-direction: column;
    gap: 10px;
    min-height: 0;
  }

  .panel {
    flex: 1;
    min-height: 0;
  }

  /* Ensure INPUT panel comes first, OUTPUT second */
  .panels .panel:has(.panel-label.output) { order: 2; }
  .panels .panel:has(.panel-label.input)  { order: 1; }

  .panel textarea {
    font-size: 0.875rem;
  }

  footer {
    padding: 12px 16px 16px;
    font-size: 0.62rem;
  }
}

/* ── Reduced Motion ───────────────────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ── High contrast support ────────────────────────────────── */
@media (prefers-contrast: more) {
  :root {
    --border:        #1e3a8a99;
    --border-strong: #2563eb;
    --text-muted:    #cbd5e1;
    --text-dim:      #64748b;
  }

  .panel textarea:focus {
    box-shadow: inset 0 0 0 3px var(--amber);
  }
}