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

:root {
  --bg:        #0a0a0b;
  --surface:   #111114;
  --border:    #2a2a30;
  --accent:    #e8ff47;
  --accent2:   #ff4747;
  --text:      #d8d8e0;
  --dim:       #555566;
  --mono:      'Share Tech Mono', monospace;
  --cond:      'Barlow Condensed', sans-serif;
}

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed; inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: .35;
  pointer-events: none;
  z-index: 0;
}

.back-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 50;
  padding: 14px 16px;
  pointer-events: none;
}
.back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(10,10,11,0.85);
  border: 1px solid var(--border);
  border-radius: 2px;
  padding: 7px 14px 7px 10px;
  color: var(--dim);
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-decoration: none;
  pointer-events: all;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: border-color 0.15s, color 0.15s;
  -webkit-tap-highlight-color: transparent;
}
.back-btn:hover { border-color: var(--accent); color: var(--accent); }
.back-arrow { font-size: 0.9rem; line-height: 1; }

.shell {
  position: relative;
  z-index: 1;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 72px 16px 64px;
}

header {
  width: 100%;
  max-width: 720px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 20px;
  margin-bottom: 32px;
  display: flex;
  align-items: flex-end;
  gap: 16px;
}

.logo-mark {
  width: 44px; height: 44px;
  border: 2px solid var(--accent);
  display: grid;
  place-items: center;
  flex-shrink: 0;
}
.logo-mark svg { width: 24px; height: 24px; }

.title-block h1 {
  font-family: var(--cond);
  font-weight: 800;
  font-size: clamp(1.7rem, 6vw, 3.2rem);
  letter-spacing: .04em;
  line-height: 1;
  color: #fff;
}
.title-block p {
  font-size: .65rem;
  color: var(--dim);
  letter-spacing: .12em;
  text-transform: uppercase;
  margin-top: 4px;
}

.panel {
  width: 100%;
  max-width: 720px;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 20px;
  margin-bottom: 24px;
}

.field-label {
  font-size: .65rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--dim);
  margin-bottom: 10px;
}

.input-row {
  display: flex;
  gap: 10px;
}

#numInput {
  flex: 1;
  min-width: 0;
  background: var(--bg);
  border: 1px solid var(--border);
  color: #fff;
  font-family: var(--mono);
  font-size: 1.2rem;
  padding: 13px 14px;
  outline: none;
  transition: border-color .15s;
  -moz-appearance: textfield;
}
#numInput::-webkit-outer-spin-button,
#numInput::-webkit-inner-spin-button { -webkit-appearance: none; }
#numInput:focus { border-color: var(--accent); }
#numInput::placeholder { color: var(--dim); font-size: 1rem; }

#runBtn {
  background: var(--accent);
  color: #000;
  font-family: var(--cond);
  font-weight: 800;
  font-size: 1rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  border: none;
  padding: 0 22px;
  cursor: pointer;
  transition: transform .1s, background .15s;
  white-space: nowrap;
  flex-shrink: 0;
  min-height: 48px;
}
#runBtn:hover { background: #f5ff88; }
#runBtn:active { transform: scale(.97); }
#runBtn:disabled { background: var(--border); color: var(--dim); cursor: not-allowed; }

.hint {
  margin-top: 10px;
  font-size: .65rem;
  color: var(--dim);
  line-height: 1.5;
}

#output {
  width: 100%;
  max-width: 720px;
  display: none;
  flex-direction: column;
  gap: 16px;
  animation: fadeUp .3s ease both;
}
#output.visible { display: flex; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

.verdict {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 28px 32px;
  border: 2px solid var(--accent);
  background: var(--surface);
}
.verdict.composite { border-color: var(--accent2); }

.verdict-icon {
  font-size: 2.4rem;
  line-height: 1;
}

.verdict-text .big {
  font-family: var(--cond);
  font-weight: 800;
  font-size: clamp(1.8rem, 5vw, 2.8rem);
  line-height: 1;
  letter-spacing: .03em;
  color: #fff;
}
.verdict-text .sub {
  font-size: .7rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--dim);
  margin-top: 4px;
}

.verdict-badge {
  margin-left: auto;
  font-family: var(--cond);
  font-weight: 600;
  font-size: .85rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  padding: 6px 14px;
  border: 1px solid currentColor;
}
.verdict-badge.prime   { color: var(--accent); }
.verdict-badge.composite { color: var(--accent2); }

.meta-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.meta-card {
  flex: 1;
  min-width: 140px;
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 16px 20px;
}
.meta-card .label {
  font-size: .62rem;
  text-transform: uppercase;
  letter-spacing: .13em;
  color: var(--dim);
  margin-bottom: 6px;
}
.meta-card .value {
  font-size: 1.05rem;
  color: #fff;
}

.factors-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 24px;
}
.factors-panel .section-title {
  font-size: .62rem;
  text-transform: uppercase;
  letter-spacing: .13em;
  color: var(--dim);
  margin-bottom: 16px;
}

.factor-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chip {
  font-size: .85rem;
  padding: 5px 12px;
  border: 1px solid var(--border);
  color: var(--text);
  background: var(--bg);
  transition: border-color .12s, color .12s;
}
.chip.prime-factor {
  border-color: var(--accent);
  color: var(--accent);
}

.progress-wrap {
  display: none;
  flex-direction: column;
  gap: 8px;
}
.progress-wrap.active { display: flex; }
.progress-label { font-size: .65rem; color: var(--dim); letter-spacing: .1em; text-transform: uppercase; }
.progress-bar {
  height: 3px;
  background: var(--border);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width .2s;
  animation: scanBar 1.2s linear infinite;
}
@keyframes scanBar {
  0%   { transform: translateX(-100%); width: 60%; }
  100% { transform: translateX(200%);  width: 60%; }
}

.history-panel {
  width: 100%;
  max-width: 720px;
  margin-top: 16px;
}
.history-title {
  font-size: .62rem;
  text-transform: uppercase;
  letter-spacing: .13em;
  color: var(--dim);
  border-bottom: 1px solid var(--border);
  padding-bottom: 10px;
  margin-bottom: 12px;
}

.history-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.history-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: border-color .12s;
  font-size: .85rem;
}
.history-item:hover { border-color: var(--dim); }
.history-item .h-num { color: #fff; flex: 1; }
.history-item .h-tag { font-size: .65rem; letter-spacing: .1em; text-transform: uppercase; }
.history-item .h-tag.prime   { color: var(--accent); }
.history-item .h-tag.composite { color: var(--accent2); }
.history-item .h-time { color: var(--dim); font-size: .7rem; }

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); }

footer {
  margin-top: 48px;
  font-size: .62rem;
  color: var(--dim);
  letter-spacing: .1em;
  text-align: center;
}

@media (max-width: 600px) {
  .shell { padding: 68px 12px 48px; }
  header { margin-bottom: 20px; padding-bottom: 16px; gap: 12px; }
  .logo-mark { width: 38px; height: 38px; }
  .logo-mark svg { width: 20px; height: 20px; }
  .title-block p { display: none; }
  .panel { padding: 16px; margin-bottom: 16px; }
  .input-row { flex-direction: column; gap: 8px; }
  #numInput { width: 100%; font-size: 1.1rem; padding: 14px 12px; }
  #runBtn { width: 100%; padding: 16px; font-size: 1.05rem; min-height: 52px; touch-action: manipulation; }
  .verdict { flex-wrap: wrap; padding: 18px 16px; gap: 10px; }
  .verdict-icon { font-size: 1.8rem; }
  .verdict-text .big { font-size: clamp(1.3rem, 7vw, 1.8rem); word-break: break-all; }
  .verdict-badge { margin-left: 0; }
  .meta-card { flex: 1 1 calc(50% - 6px); min-width: 0; padding: 12px 14px; }
  .meta-card .value { font-size: .95rem; }
  .factors-panel { padding: 14px; }
  .chip { font-size: .78rem; padding: 5px 9px; }
  .history-item { flex-wrap: wrap; gap: 6px; padding: 10px 12px; }
  .history-item .h-time { width: 100%; margin-top: 2px; }
  footer { margin-top: 32px; }
}

@media (max-width: 360px) {
  .title-block h1 { font-size: 1.5rem; }
  .meta-card { flex: 1 1 100%; }
}