/* ────────────────────────────────────────────
   TeknikGo — Main Stylesheet
   Dark tech aesthetic, Indonesian student platform
──────────────────────────────────────────── */

:root {
  --bg: #0a0e1a;
  --surface: #111827;
  --card: #1a2235;
  --card-hover: #1f2a40;
  --border: #2a3550;
  --border-light: #1e2d45;

  --blue: #3b82f6;
  --blue-dim: rgba(59,130,246,0.12);
  --green: #10b981;
  --green-dim: rgba(16,185,129,0.12);
  --amber: #f59e0b;
  --amber-dim: rgba(245,158,11,0.12);
  --purple: #8b5cf6;
  --purple-dim: rgba(139,92,246,0.12);
  --red: #ef4444;

  --text: #f1f5f9;
  --text-2: #94a3b8;
  --text-3: #4a5a75;

  --mono: 'JetBrains Mono', monospace;
  --sans: 'DM Sans', sans-serif;
  --display: 'Syne', sans-serif;

  --sidebar-w: 220px;
  --radius: 10px;
  --radius-sm: 6px;
}

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

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 14px;
  line-height: 1.6;
}

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

/* ─────────── SIDEBAR ─────────── */
.sidebar {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: var(--sidebar-w);
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  z-index: 100;
  overflow-y: auto;
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 22px 20px 18px;
  border-bottom: 1px solid var(--border);
}

.logo-icon {
  font-size: 22px;
  color: var(--blue);
  line-height: 1;
}

.logo-text {
  font-family: var(--display);
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.3px;
}

.logo-text em {
  font-style: normal;
  color: var(--blue);
}

.sidebar-nav {
  flex: 1;
  padding: 12px 10px;
}

.nav-section-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--text-3);
  padding: 16px 10px 6px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-radius: var(--radius-sm);
  color: var(--text-2);
  cursor: pointer;
  text-decoration: none;
  font-size: 13.5px;
  transition: all 0.15s;
  margin-bottom: 2px;
}

.nav-icon {
  font-size: 16px;
  width: 20px;
  text-align: center;
  line-height: 1;
}

.nav-item:hover {
  background: var(--card);
  color: var(--text);
}

.nav-item.active {
  background: var(--blue-dim);
  color: var(--blue);
  font-weight: 500;
}

.sidebar-footer {
  padding: 14px 16px;
  border-top: 1px solid var(--border);
}

.badge-powered {
  font-size: 10px;
  color: var(--text-3);
  text-align: center;
}

/* ─────────── MOBILE HEADER ─────────── */
.mobile-header {
  display: none;
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 52px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  z-index: 200;
}

.mob-menu-btn {
  background: none;
  border: none;
  color: var(--text);
  font-size: 20px;
  cursor: pointer;
  padding: 4px 8px;
}

.mobile-nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  z-index: 150;
}

/* ─────────── MAIN ─────────── */
.main-content {
  margin-left: var(--sidebar-w);
  min-height: 100vh;
  padding: 32px 36px;
  max-width: 1200px;
}

/* ─────────── PAGE HEADER ─────────── */
.page-header {
  margin-bottom: 28px;
}

.page-header h1 {
  font-family: var(--display);
  font-size: 26px;
  font-weight: 700;
  margin-bottom: 6px;
  letter-spacing: -0.5px;
}

.page-header p {
  color: var(--text-2);
  font-size: 14px;
}

/* ─────────── STATS ─────────── */
.stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin-bottom: 28px;
}

.stat-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  text-align: center;
}

.stat-num {
  font-family: var(--display);
  font-size: 32px;
  font-weight: 700;
  line-height: 1;
  margin-bottom: 6px;
}

.stat-num.blue { color: var(--blue); }
.stat-num.green { color: var(--green); }
.stat-num.amber { color: var(--amber); }
.stat-num.purple { color: var(--purple); }

.stat-label {
  font-size: 12px;
  color: var(--text-2);
}

/* ─────────── FEATURE GRID ─────────── */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-bottom: 24px;
}

.feature-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  cursor: pointer;
  transition: all 0.2s;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  opacity: 0;
  transition: opacity 0.2s;
}

.feature-card:hover {
  background: var(--card-hover);
  transform: translateY(-1px);
}

.feature-card:hover::before { opacity: 1; }

.card-blue::before { background: var(--blue); }
.card-green::before { background: var(--green); }
.card-amber::before { background: var(--amber); }
.card-purple::before { background: var(--purple); }

.feature-icon {
  font-size: 24px;
  margin-bottom: 10px;
  line-height: 1;
}

.card-blue .feature-icon { color: var(--blue); }
.card-green .feature-icon { color: var(--green); }
.card-amber .feature-icon { color: var(--amber); }
.card-purple .feature-icon { color: var(--purple); }

.feature-card h3 {
  font-family: var(--display);
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
}

.feature-card p {
  font-size: 12.5px;
  color: var(--text-2);
  line-height: 1.5;
  margin-bottom: 14px;
}

/* ─────────── INFO BANNER ─────────── */
.info-banner {
  background: var(--blue-dim);
  border: 1px solid rgba(59,130,246,0.25);
  border-radius: var(--radius);
  padding: 14px 18px;
  display: flex;
  gap: 12px;
  align-items: flex-start;
  font-size: 13px;
  color: var(--text-2);
}

.info-icon { font-size: 16px; line-height: 1.6; }

.info-banner strong { color: var(--text); }

/* ─────────── TABS ─────────── */
.tab-section { display: none; }
.tab-section.active { display: block; }

/* ─────────── LAYOUT ─────────── */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  align-items: start;
}

.col-left, .col-right { display: flex; flex-direction: column; gap: 14px; }

/* ─────────── FORMS ─────────── */
.form-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
}

.form-group {
  margin-bottom: 14px;
}

.form-group:last-child { margin-bottom: 0; }

.form-group label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-2);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: .5px;
}

input[type="text"],
input[type="number"],
textarea,
select {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: var(--sans);
  font-size: 13px;
  padding: 9px 12px;
  transition: border-color 0.15s;
  outline: none;
}

input[type="text"]:focus,
input[type="number"]:focus,
textarea:focus,
select:focus {
  border-color: var(--blue);
}

select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6'%3E%3Cpath d='M0 0l5 6 5-6z' fill='%2394a3b8'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 32px;
}

textarea {
  resize: vertical;
  min-height: 100px;
  line-height: 1.6;
}

.two-input-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

/* ─────────── BUTTONS ─────────── */
.btn-primary {
  width: 100%;
  padding: 10px 20px;
  background: var(--blue);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
}

.btn-primary:hover { background: #2563eb; }
.btn-primary:disabled { opacity: .5; cursor: default; }

.btn-secondary {
  padding: 8px 14px;
  background: var(--card);
  color: var(--text-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--sans);
  font-size: 12px;
  cursor: pointer;
  transition: all 0.15s;
  white-space: nowrap;
}

.btn-secondary:hover { background: var(--card-hover); color: var(--text); }

/* ─────────── CHIPS ─────────── */
.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 12px;
}

.chip {
  padding: 5px 11px;
  font-size: 11.5px;
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
  color: var(--text-2);
  background: transparent;
  transition: all 0.15s;
  white-space: nowrap;
}

.chip:hover { border-color: var(--blue); color: var(--blue); background: var(--blue-dim); }

.chip-blue  { background: var(--blue-dim);   color: var(--blue);   border-color: rgba(59,130,246,.3); }
.chip-green { background: var(--green-dim);  color: var(--green);  border-color: rgba(16,185,129,.3); }
.chip-amber { background: var(--amber-dim);  color: var(--amber);  border-color: rgba(245,158,11,.3); }
.chip-purple{ background: var(--purple-dim); color: var(--purple); border-color: rgba(139,92,246,.3); }

/* ─────────── RESULT BOX ─────────── */
.result-box {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  font-size: 13px;
  line-height: 1.8;
  white-space: pre-wrap;
  word-break: break-word;
  color: var(--text);
}

/* ─────────── REF CARD ─────────── */
.ref-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}

.ref-card h4 {
  font-family: var(--display);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .5px;
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: 12px;
}

.formula-table {
  width: 100%;
  border-collapse: collapse;
}

.formula-table td {
  padding: 5px 4px;
  font-size: 12px;
  border-bottom: 1px solid var(--border-light);
  vertical-align: middle;
}

.formula-table tr:last-child td { border-bottom: none; }

.formula-table td:first-child {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--blue);
  width: 50%;
}

.formula-table td:last-child { color: var(--text-2); }

.chart-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}

.chart-card h4 {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .5px;
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: 12px;
}

/* ─────────── AI TUTOR LAYOUT ─────────── */
.tutor-layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 20px;
  align-items: start;
}

.tutor-left { display: flex; flex-direction: column; gap: 14px; }

.quick-prompts { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; }

.ql {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .5px;
  text-transform: uppercase;
  color: var(--text-3);
  margin-bottom: 10px;
}

/* ─────────── CHAT ─────────── */
.chat-container {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  height: 520px;
  overflow: hidden;
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.chat-msg {
  display: flex;
  gap: 10px;
  align-items: flex-start;
}

.chat-msg.user { flex-direction: row-reverse; }

.msg-avatar {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--blue-dim);
  border: 1px solid rgba(59,130,246,.3);
  color: var(--blue);
  font-size: 10px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-family: var(--display);
}

.chat-msg.user .msg-avatar {
  background: var(--green-dim);
  border-color: rgba(16,185,129,.3);
  color: var(--green);
}

.msg-body {
  max-width: 78%;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 13px;
  font-size: 13px;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
}

.chat-msg.user .msg-body {
  background: var(--blue-dim);
  border-color: rgba(59,130,246,.25);
}

.chat-input-row {
  display: flex;
  gap: 8px;
  padding: 12px;
  border-top: 1px solid var(--border);
  background: var(--surface);
}

.chat-input-row input {
  flex: 1;
}

.send-btn {
  padding: 9px 18px;
  background: var(--blue);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s;
  white-space: nowrap;
}

.send-btn:hover { background: #2563eb; }
.send-btn:disabled { opacity: .5; }

/* ─────────── PROB / SLIDERS ─────────── */
.slider-group { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px; }

.slider-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.slider-row label {
  font-size: 12px;
  color: var(--text-2);
  font-weight: 500;
}

.slider-val {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--blue);
  font-weight: 500;
}

input[type="range"] {
  width: 100%;
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  outline: none;
  -webkit-appearance: none;
  border: none;
  padding: 0;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  background: var(--blue);
  border-radius: 50%;
  cursor: pointer;
}

.prob-calc-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
  font-size: 13px;
  color: var(--text-2);
}

.prob-calc-row input {
  width: 70px;
  text-align: center;
  padding: 6px 8px;
  font-family: var(--mono);
}

.prob-result {
  font-family: var(--display);
  font-size: 26px;
  font-weight: 700;
  color: var(--blue);
}

.formula-text {
  font-family: var(--mono);
  font-size: 11.5px;
  line-height: 1.9;
  color: var(--text-2);
}

/* ─────────── pH SCALE ─────────── */
.ph-scale-bar {
  position: relative;
  height: 12px;
  border-radius: 6px;
  background: linear-gradient(to right, #ef4444, #f97316, #eab308, #22c55e, #3b82f6, #8b5cf6);
  margin-top: 10px;
}

.ph-indicator {
  position: absolute;
  top: -5px;
  width: 10px;
  height: 22px;
  background: #fff;
  border-radius: 3px;
  box-shadow: 0 0 0 2px var(--border);
  transform: translateX(-50%);
  transition: left 0.4s;
}

.ph-labels {
  display: flex;
  justify-content: space-between;
  font-size: 10px;
  color: var(--text-3);
  margin-top: 4px;
}

/* ─────────── PYTHON IDE ─────────── */
.ide-layout {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.ide-toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  flex-wrap: wrap;
}

.btn-run {
  padding: 7px 16px;
  background: var(--green);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--sans);
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s;
  white-space: nowrap;
}

.btn-run:hover { background: #059669; }
.btn-run:disabled { opacity: .5; }

.ide-body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  height: 420px;
}

.ide-editor-wrap {
  display: flex;
  border-right: 1px solid var(--border);
  overflow: hidden;
}

.ide-line-nums {
  padding: 14px 8px;
  background: var(--surface);
  color: var(--text-3);
  font-family: var(--mono);
  font-size: 12px;
  line-height: 1.7;
  text-align: right;
  min-width: 36px;
  user-select: none;
  white-space: pre;
  overflow: hidden;
}

.ide-editor {
  flex: 1;
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.7;
  padding: 14px 14px 14px 10px;
  border: none;
  resize: none;
  outline: none;
  overflow-y: auto;
  tab-size: 4;
  white-space: pre;
}

.ide-editor::-webkit-scrollbar { display: none; }

.ide-output-wrap {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.ide-output-header {
  padding: 8px 14px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .5px;
  text-transform: uppercase;
  color: var(--text-3);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.ide-output {
  flex: 1;
  padding: 14px;
  font-family: var(--mono);
  font-size: 12px;
  line-height: 1.7;
  color: var(--text-2);
  overflow-y: auto;
  white-space: pre-wrap;
  word-break: break-word;
}

/* ─────────── STATUS BADGE ─────────── */
.status-badge {
  font-size: 11px;
  padding: 3px 10px;
  border-radius: 999px;
  font-weight: 500;
}

.status-loading { background: var(--amber-dim); color: var(--amber); }
.status-ready   { background: var(--green-dim);  color: var(--green); }
.status-error   { background: rgba(239,68,68,.12); color: var(--red); }

/* ─────────── LOADING SPINNER ─────────── */
.spinner {
  display: inline-block;
  width: 13px; height: 13px;
  border: 2px solid var(--border);
  border-top-color: var(--blue);
  border-radius: 50%;
  animation: spin .7s linear infinite;
  vertical-align: middle;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* ─────────── RESPONSIVE ─────────── */
@media (max-width: 900px) {
  .sidebar { transform: translateX(-100%); transition: transform 0.25s; }
  .sidebar.open { transform: translateX(0); }
  .mobile-header { display: flex; }
  .mobile-nav-overlay.open { display: block; }
  .main-content { margin-left: 0; padding: 80px 16px 24px; }
  .two-col { grid-template-columns: 1fr; }
  .tutor-layout { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: 1fr 1fr; }
  .stats-row { grid-template-columns: repeat(2, 1fr); }
  .ide-body { grid-template-columns: 1fr; grid-template-rows: 240px 180px; height: auto; }
  .ide-editor-wrap { border-right: none; border-bottom: 1px solid var(--border); }
}

@media (max-width: 560px) {
  .features-grid { grid-template-columns: 1fr; }
  .stats-row { grid-template-columns: repeat(2, 1fr); }
}