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

:root {
  --bg-base:       #0d1117;
  --bg-surface:    #161b22;
  --bg-elevated:   #21262d;
  --border:        #30363d;
  --accent-green:  #00ff88;
  --accent-cyan:   #00d4ff;
  --accent-muted:  #3fb950;
  --text-primary:  #e6edf3;
  --text-secondary:#8b949e;
  --text-dim:      #484f58;
  --status-ok:     #3fb950;
  --status-loading:#d29922;
  --status-error:  #f85149;
  --font-mono:     'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  --font-ui:       'Inter', system-ui, sans-serif;
  --nav-height:    48px;
  --sidebar-width: 320px;
  --transition:    0.25s ease;
}

/* ─── Reset ──────────────────────────────────────────────── */

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

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg-base);
  color: var(--text-primary);
  font-family: var(--font-ui);
  font-size: 15px;
  line-height: 1.6;
}

/* Subtle dot-grid background */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: radial-gradient(circle, rgba(0, 255, 136, 0.05) 1px, transparent 1px);
  background-size: 28px 28px;
  pointer-events: none;
  z-index: -1;
}

a {
  color: var(--accent-cyan);
  text-decoration: none;
}
a:hover { text-decoration: underline; }

/* Thin green scrollbar */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg-base); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent-green); }

/* ─── Navigation bar ─────────────────────────────────────── */

.nav-bar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.25rem;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
}

.nav-brand {
  font-family: var(--font-mono);
  font-size: 1.88rem;
  color: var(--accent-green);
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.nav-links {
  display: flex;
  gap: 1.25rem;
  align-items: center;
  flex-wrap: wrap;
}

.nav-links a {
  font-size: 0.8rem;
  color: var(--text-secondary);
  white-space: nowrap;
}
.nav-links a:hover { color: var(--accent-cyan); text-decoration: none; }

/* ─── App shell: sidebar + main ──────────────────────────── */

.app-shell {
  display: flex;
  height: calc(100vh - var(--nav-height));
  overflow: hidden;
}

/* ─── Sidebar ────────────────────────────────────────────── */

.sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  overflow: hidden;
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  transition: width var(--transition), min-width var(--transition);
  flex-shrink: 0;
}

.app-shell.sidebar-open .sidebar {
  overflow-y: auto;
}

.app-shell.sidebar-closed .sidebar {
  width: 0;
  min-width: 0;
}

.sidebar-header {
  position: sticky;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.65rem 1rem;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
  z-index: 10;
}

.sidebar-close {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 0.9rem;
  padding: 2px 6px;
  border-radius: 4px;
  line-height: 1;
  margin: 0;
  font-family: var(--font-ui);
}
.sidebar-close:hover { color: var(--text-primary); background: var(--bg-elevated); }

.sidebar-content {
  padding: 0.85rem 1rem;
  white-space: normal;
}

/* ─── Tutorial content ───────────────────────────────────── */

.tutorial-intro {
  padding-bottom: 0.75rem;
  margin-bottom: 0.75rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.83rem;
  color: var(--text-secondary);
}

.tutorial-step {
  border-left: 2px solid var(--border);
  padding: 0.7rem 0 0.7rem 1rem;
  margin: 0.5rem 0;
  transition: border-color 0.15s;
}
.tutorial-step:hover { border-left-color: var(--accent-green); }

.tutorial-card-link {
  display: block;
  text-decoration: none;
  color: inherit;
}

.tutorial-card {
  cursor: pointer;
}

.tutorial-back {
  display: inline-block;
  font-size: 0.8rem;
  color: var(--accent-green);
  cursor: pointer;
  margin-bottom: 0.25rem;
}

.step-number {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--accent-green);
  letter-spacing: 0.12em;
  margin-bottom: 0.25rem;
}

.tutorial-step h4 {
  margin: 0 0 0.3rem;
  color: var(--text-primary);
  font-size: 0.88rem;
  font-weight: 600;
}

.tutorial-step p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin: 0.2rem 0;
}

.tutorial-step ul, .tutorial-step ol {
  font-size: 0.82rem;
  color: var(--text-secondary);
  padding-left: 1.2rem;
  margin: 0.3rem 0;
  line-height: 1.65;
}

.tutorial-code {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.35rem 0.65rem;
  margin-top: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--accent-green);
  word-break: break-all;
}

.tutorial-step code {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  background: var(--bg-elevated);
  color: var(--accent-cyan);
  padding: 1px 5px;
  border-radius: 3px;
}

/* ─── Main content area ──────────────────────────────────── */

.main-content {
  flex: 1;
  overflow-y: auto;
  padding: 1rem 1.5rem 2rem;
  min-width: 0;
}

.sidebar-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  padding: 0.3rem 0.75rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  border-radius: 6px;
  cursor: pointer;
  margin-bottom: 0.9rem;
  transition: border-color var(--transition), color var(--transition);
}
.sidebar-toggle:hover,
.app-shell.sidebar-open .sidebar-toggle {
  border-color: var(--accent-green);
  color: var(--accent-green);
}

/* ─── Panel ──────────────────────────────────────────────── */

.panel {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
}

h1 {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--text-primary);
  margin: 0 0 1.25rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border);
}

h1::before {
  content: '> ';
  color: var(--accent-green);
}

.section-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent-green);
  margin-bottom: 0.5rem;
}

/* ─── Info box ───────────────────────────────────────────── */

.info-box {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem 1rem;
  margin-bottom: 0.75rem;
  font-size: 0.84rem;
  color: var(--text-secondary);
}
.info-box p { margin: 0.25rem 0 0; }
.info-box ol, .info-box ul {
  margin: 0.4rem 0 0;
  padding-left: 1.4rem;
  line-height: 1.75;
}

/* Collapsible info-box via <details> */
details.info-box summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  user-select: none;
  list-style: none;
  margin-bottom: 0;
}
details.info-box[open] summary { margin-bottom: 0.45rem; }
details.info-box summary::-webkit-details-marker { display: none; }
details.info-box summary::marker { display: none; }
details.info-box summary::after {
  content: '[ + ]';
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--accent-green);
  flex-shrink: 0;
}
details.info-box[open] summary::after { content: '[ − ]'; }

/* Title inside summary — styled like h1 */
.info-title {
  font-family: var(--font-mono);
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-primary);
}
.info-title::before {
  content: '> ';
  color: var(--accent-green);
}

/* ─── Sections ───────────────────────────────────────────── */

.upload-section, .code-section { margin: 1.1rem 0; }

/* ─── Form controls ──────────────────────────────────────── */

select, input[type="file"] {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-primary);
  font-family: var(--font-ui);
  font-size: 0.875rem;
  padding: 0.45rem 0.75rem;
  width: 100%;
  max-width: 420px;
  transition: border-color var(--transition);
}
select:focus, input:focus { outline: none; border-color: var(--accent-green); }
select option { background: var(--bg-elevated); }
input[type="file"] { cursor: pointer; padding: 0.4rem; max-width: 420px; }

#loadInfo, #fileInfo {
  font-size: 0.81rem;
  margin-top: 0.45rem;
  color: var(--text-secondary);
}

/* ─── Code editor ────────────────────────────────────────── */

textarea {
  width: 100%;
  font-family: var(--font-mono);
  font-size: 0.81rem;
  line-height: 1.65;
  padding: 0.75rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-primary);
  resize: vertical;
  transition: border-color var(--transition);
  box-sizing: border-box;
}
textarea:focus { outline: none; border-color: var(--accent-green); }

/* ─── Buttons ────────────────────────────────────────────── */

button {
  font-family: var(--font-ui);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 0.5rem 1.4rem;
  border-radius: 6px;
  cursor: pointer;
  transition: all var(--transition);
  border: 1px solid transparent;
  line-height: 1.4;
}

#runButton {
  background: var(--accent-green);
  color: #0d1117;
  border-color: var(--accent-green);
  margin-top: 0.75rem;
}
#runButton:hover:not(:disabled) {
  box-shadow: 0 0 18px rgba(0, 255, 136, 0.35);
  background: #1aff99;
}
#runButton:disabled {
  background: var(--bg-elevated);
  border-color: var(--border);
  color: var(--text-dim);
  cursor: not-allowed;
  box-shadow: none;
}

/* ─── Status messages ────────────────────────────────────── */

#status {
  margin: 0.75rem 0;
  padding: 0.55rem 0.9rem;
  border-radius: 6px;
  font-size: 0.84rem;
  display: none;
  font-family: var(--font-mono);
}
#status.loading {
  display: block;
  background: rgba(210, 153, 34, 0.08);
  border: 1px solid var(--status-loading);
  color: var(--status-loading);
}
#status.success {
  display: block;
  background: rgba(63, 185, 80, 0.08);
  border: 1px solid var(--status-ok);
  color: var(--status-ok);
}
#status.error {
  display: block;
  background: rgba(248, 81, 73, 0.08);
  border: 1px solid var(--status-error);
  color: var(--status-error);
}

/* ─── Output / results ───────────────────────────────────── */

#output { margin-top: 0.85rem; }

.results {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent-green);
  border-radius: 0 6px 6px 0;
  padding: 0.85rem 1rem;
  margin-top: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.79rem;
  color: var(--text-primary);
  white-space: pre-wrap;
  word-break: break-word;
  line-height: 1.6;
}

#plot {
  display: none;
  max-width: 100%;
  margin-top: 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
}

#plotly-container {
  display: none;
  margin-top: 1rem;
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
  height: 500px;
  width: 100%;
}

/* ─── Utility ────────────────────────────────────────────── */

.text-dim { color: var(--text-dim); font-size: 0.82rem; }

/* ─── Mobile ─────────────────────────────────────────────── */

@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    bottom: 0;
    z-index: 200;
    width: min(var(--sidebar-width), 88vw) !important;
    min-width: 0 !important;
    transform: translateX(-100%);
    transition: transform var(--transition);
    box-shadow: 4px 0 24px rgba(0, 0, 0, 0.6);
    overflow-y: auto;
  }
  .app-shell.sidebar-open .sidebar {
    transform: translateX(0);
  }
  .app-shell.sidebar-closed .sidebar {
    transform: translateX(-100%);
  }
  .main-content { padding: 0.75rem; }
  .panel { padding: 1rem; }
  .nav-links { display: none; }
}

/* ─── Converter page ─────────────────────────────────── */

.converter-section { margin-bottom: 1.25rem; }

.converter-section > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  user-select: none;
  list-style: none;
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 1.1rem;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-primary);
}
.converter-section > summary::-webkit-details-marker { display: none; }
.converter-section > summary::marker { display: none; }
.converter-section > summary::after {
  content: '[ + ]';
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--accent-green);
  flex-shrink: 0;
}
.converter-section[open] > summary::after { content: '[ − ]'; }
.converter-section[open] > summary { border-bottom-color: var(--accent-green); }

.conv-title::before { content: '> '; color: var(--accent-green); }

.conv-desc {
  font-size: 0.84rem;
  color: var(--text-secondary);
  margin: 0 0 1.1rem;
  line-height: 1.6;
}

.radio-group {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  margin-top: 0.1rem;
}
.radio-group label {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  cursor: pointer;
  font-size: 0.875rem;
  color: var(--text-secondary);
}
.radio-group label:hover { color: var(--text-primary); }
.radio-group input[type="radio"] {
  accent-color: var(--accent-green);
  width: 0.95rem;
  height: 0.95rem;
  cursor: pointer;
}
.radio-hint {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-dim);
}

.sep-grid {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  align-items: flex-end;
}
.sep-field {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.sep-field label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent-green);
}
.sep-field input[type="text"] {
  width: 5rem;
  padding: 0.4rem 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  text-align: center;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-primary);
  transition: border-color var(--transition);
}
.sep-field input[type="text"]:focus { outline: none; border-color: var(--accent-green); }
.sep-hint {
  font-family: var(--font-mono);
  font-size: 0.71rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
}
.sep-hint code { color: var(--accent-cyan); font-family: var(--font-mono); }

.conv-btn {
  background: var(--accent-green);
  color: #0d1117;
  border-color: var(--accent-green);
  margin-top: 0.75rem;
}
.conv-btn:hover {
  box-shadow: 0 0 18px rgba(0, 255, 136, 0.35);
  background: #1aff99;
}

.copy-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 0.8rem;
  padding: 0.3rem 0.8rem;
  margin-top: 0.5rem;
}
.copy-btn:hover { border-color: var(--accent-cyan); color: var(--accent-cyan); }

.status-msg {
  margin: 0.75rem 0 0;
  padding: 0.55rem 0.9rem;
  border-radius: 6px;
  font-size: 0.84rem;
  display: none;
  font-family: var(--font-mono);
}
.status-msg.loading { display: block; background: rgba(210,153,34,0.08); border: 1px solid var(--status-loading); color: var(--status-loading); }
.status-msg.success { display: block; background: rgba(63,185,80,0.08);  border: 1px solid var(--status-ok);      color: var(--status-ok); }
.status-msg.error   { display: block; background: rgba(248,81,73,0.08);  border: 1px solid var(--status-error);   color: var(--status-error); }

.stats-line {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-dim);
  margin-top: 0.35rem;
}

textarea[readonly] { opacity: 0.85; cursor: default; }