:root {
  --bg:       #F7F5F0;
  --surface:  #FFFFFF;
  --border:   #E2DDD6;
  --ink:      #1A1714;
  --ink2:     #6B6560;
  --accent:   #C8410A;
  --accent-l: #F2E8E3;
  --green:    #1A6B3A;
  --green-l:  #E3F0E9;
  --blue:     #1A4A8A;
  --blue-l:   #E3EBF7;
  --r: 8px;
  --mono: 'IBM Plex Mono', monospace;
  --serif: 'Fraunces', Georgia, serif;
}

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

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--mono);
  font-size: 14px;
  min-height: 100vh;
}

/* Subtle graph-paper background */
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: 32px 32px;
  opacity: 0.35;
  pointer-events: none;
  z-index: -1;
}

.page {
  position: relative;
  max-width: 1280px;
  margin: 0 auto;
  padding: 3rem 2rem 4rem;
}

/* Two-column layout */
.layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 2rem;
  align-items: start;
}
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
}
.main-col { min-width: 0; }

/* Sidebar references */
.sidebar {
  position: sticky;
  top: 2rem;
}
.sidebar-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1.2rem 1.4rem;
  font-size: 11px;
  color: var(--ink2);
  line-height: 1.8;
}
.sidebar-card strong {
  display: block;
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink);
  margin-bottom: 0.75rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}
.sidebar-card p { margin-bottom: 0.75rem; }
.sidebar-card p:last-child { margin-bottom: 0; }
.sidebar-card a { color: var(--ink2); }
.sidebar-card em { font-style: italic; }

/* ── Header ─────────────────────────────────────── */
header {
  margin-bottom: 2.5rem;
  border-bottom: 2px solid var(--ink);
  padding-bottom: 1.5rem;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1rem;
  animation: fadeDown 0.5s ease both;
}
@media (max-width: 600px) {
  header { flex-direction: column; align-items: flex-start; }
  .header-meta { text-align: left; }
}

.title-block h1 {
  font-family: var(--serif);
  font-size: 3rem;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--ink);
}
.title-block h1 span { color: var(--accent); font-style: italic; }
.title-block p {
  margin-top: 0.4rem;
  font-size: 11px;
  color: var(--ink2);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.header-meta {
  text-align: right;
  font-size: 11px;
  color: var(--ink2);
  line-height: 1.9;
}
.version-badge {
  display: inline-block;
  background: var(--ink);
  color: var(--bg);
  padding: 2px 8px;
  border-radius: 3px;
  font-size: 10px;
  letter-spacing: 0.1em;
  font-weight: 500;
}

/* ── Section label ───────────────────────────────── */
.section-label {
  font-size: 10px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink2);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.section-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* ── Card ────────────────────────────────────────── */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1.5rem;
  margin-bottom: 1rem;
  animation: fadeUp 0.4s ease both;
}
.card:nth-child(2) { animation-delay: 0.06s; }
.card:nth-child(3) { animation-delay: 0.12s; }
.card:nth-child(4) { animation-delay: 0.18s; }

/* ── Mode tabs ───────────────────────────────────── */
.mode-tabs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}
@media (max-width: 500px) { .mode-tabs { grid-template-columns: 1fr; } }
.tab-btn {
  padding: 0.7rem 1rem;
  border: 1.5px solid var(--border);
  border-radius: 6px;
  background: transparent;
  color: var(--ink2);
  font-family: var(--mono);
  font-size: 12px;
  cursor: pointer;
  transition: all 0.15s;
  text-align: left;
  line-height: 1.5;
}
.tab-btn strong { display: block; color: var(--ink); font-size: 13px; margin-bottom: 0.2rem; }
.tab-btn:hover { border-color: var(--ink); color: var(--ink); }
.tab-btn.active {
  border-color: var(--accent);
  background: var(--accent-l);
  color: var(--accent);
}
.tab-btn.active strong { color: var(--accent); }

/* ── Input panels ────────────────────────────────── */
/* Drop zone */
.drop-zone {
  border: 2px dashed var(--border);
  border-radius: var(--r);
  padding: 2.5rem 1.5rem;
  text-align: center;
  cursor: pointer;
  position: relative;
  transition: all 0.15s;
}
.drop-zone:hover, .drop-zone.drag-active {
  border-color: var(--accent);
  background: var(--accent-l);
}
.drop-zone input[type="file"] {
  position: absolute; inset: 0;
  opacity: 0; cursor: pointer;
  width: 100%; height: 100%;
}
.drop-icon { font-size: 2rem; margin-bottom: 0.5rem; }
.drop-text { font-size: 12px; color: var(--ink2); line-height: 1.7; }
.drop-text strong { color: var(--ink); }
.file-chosen {
  margin-top: 0.75rem;
  font-size: 12px;
  color: var(--green);
  font-weight: 500;
}

/* Drive input */
.drive-input-wrap { display: flex; gap: 0.5rem; align-items: stretch; }
.drive-input-wrap input[type="text"] {
  flex: 1;
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: 6px;
  padding: 0.65rem 0.9rem;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink);
  outline: none;
  transition: border-color 0.15s;
}
.drive-input-wrap input[type="text"]:focus { border-color: var(--accent); }
.drive-hint {
  font-size: 11px;
  color: var(--ink2);
  margin-top: 0.5rem;
  line-height: 1.7;
}
.drive-hint a { color: var(--blue); }

/* ── Parameters ──────────────────────────────────── */
.param-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 0.75rem;
}
@media (max-width: 600px) { .param-grid { grid-template-columns: 1fr 1fr; } }
.param-item label {
  display: block;
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink2);
  margin-bottom: 0.35rem;
}
.param-item input {
  width: 100%;
  background: var(--bg);
  border: 1.5px solid var(--border);
  border-radius: 6px;
  padding: 0.55rem 0.75rem;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--ink);
  outline: none;
  transition: border-color 0.15s;
}
.param-item input:focus { border-color: var(--accent); }
.param-hint { font-size: 10px; color: var(--ink2); margin-top: 0.2rem; }

/* ── Buttons ─────────────────────────────────────── */
.btn-run {
  width: 100%;
  padding: 0.9rem;
  background: var(--ink);
  color: var(--bg);
  border: none;
  border-radius: var(--r);
  font-family: var(--mono);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  letter-spacing: 0.04em;
  margin-top: 0.5rem;
}
.btn-run:hover:not(:disabled) {
  background: var(--accent);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(200,65,10,0.2);
}
.btn-run:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }

.btn-download {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  width: 100%;
  padding: 0.85rem;
  background: var(--green-l);
  color: var(--green);
  border: 1.5px solid var(--green);
  border-radius: var(--r);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.15s;
}
.btn-download:hover {
  background: var(--green);
  color: white;
  transform: translateY(-1px);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 0.8rem;
  background: var(--surface);
  color: var(--ink);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 12px;
  cursor: pointer;
  transition: all 0.15s;
}
.btn-secondary:hover {
  border-color: var(--ink);
}

/* ── Progress & Error ────────────────────────────── */
.progress-meta {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: var(--ink2);
  margin-bottom: 0.5rem;
}

.log-box {
  background: var(--ink);
  color: #C8C4BE;
  border-radius: 6px;
  padding: 1rem;
  font-size: 11px;
  line-height: 1.8;
  max-height: 180px;
  overflow-y: auto;
  margin-top: 0.75rem;
  white-space: pre-wrap;
  word-break: break-all;
}

.alert-error {
  background: rgba(235, 87, 87, 0.1);
  border: 1px solid rgba(235, 87, 87, 0.3);
  color: #EB5757;
  padding: 1rem;
  border-radius: var(--r);
  font-size: 12px;
  margin-bottom: 1rem;
}
.alert-warning {
  background: rgba(251, 191, 36, 0.1);
  border: 1px solid rgba(251, 191, 36, 0.3);
  color: #d97706;
  padding: 1rem;
  border-radius: var(--r);
  font-size: 12px;
  margin-bottom: 1rem;
}

/* ── Results ─────────────────────────────────────── */
.stats-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 1rem;
}
.stat-box {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 0.9rem 1rem;
  text-align: center;
}
.stat-val {
  font-family: var(--serif);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
}
.stat-label {
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink2);
  margin-top: 0.3rem;
}

/* ── Animations ──────────────────────────────────── */
@keyframes fadeUp   { from { opacity:0; transform:translateY(12px); } to { opacity:1; transform:translateY(0); } }
@keyframes fadeDown { from { opacity:0; transform:translateY(-8px); } to { opacity:1; transform:translateY(0); } }

/* ── Scrollbar ───────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* Loader */
.loader {
  display: inline-block;
  width: 16px;
  height: 16px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 1s ease-in-out infinite;
  margin-right: 8px;
  vertical-align: middle;
}
@keyframes spin { to { transform: rotate(360deg); } }