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

:root {
  --accent: #14b8a6;
  --accent-lo: rgba(20, 184, 166, .22);
}

body { padding: 0 16px; }
#app { max-width: 1280px; margin: 0 auto; display: flex; flex-direction: column; gap: 14px; padding-top: 8px; }

#app > header { text-align: center; padding: 4px 0; }
#app > header h1 {
  font-size: clamp(1.4rem, 2.6vw, 2.0rem);
  font-weight: 800;
  background: linear-gradient(90deg, var(--accent), #5eead4);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  line-height: 1.2;
}
#app > header .subtitle { color: var(--text-dim); font-size: 0.88rem; margin-top: 3px; max-width: 1000px; margin-left: auto; margin-right: auto; }

/* Controls bar */
.controls-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 20px;
}

.pill-tabs {
  display: inline-flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 4px;
  gap: 2px;
}
.pill-tab {
  padding: 8px 18px;
  border: none;
  background: transparent;
  color: var(--text-dim);
  font-weight: 600;
  font-size: 0.9rem;
  border-radius: 999px;
  cursor: pointer;
  transition: all .15s;
}
.pill-tab:hover { color: var(--text); }
.pill-tab.active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 2px 8px var(--accent-lo);
}

.unit-toggle {
  display: inline-flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 3px;
  gap: 2px;
}
.unit-btn {
  padding: 6px 14px;
  border: none;
  background: transparent;
  color: var(--text-dim);
  font-weight: 700;
  font-size: 0.82rem;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--mono);
}
.unit-btn.active { background: var(--accent); color: #fff; }

/* Layout */
.psy-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 380px;
  gap: 16px;
  align-items: start;
}

/* Canvas card */
.canvas-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px;
  position: relative;
  overflow-x: clip;
}

.chart-toolbar {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 8px;
}
.chart-tool-group { display: flex; gap: 4px; flex-wrap: wrap; }
.chart-tool-btn {
  padding: 6px 10px;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text-dim);
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: 6px;
  cursor: pointer;
  transition: all .15s;
}
.chart-tool-btn:hover { color: var(--text); border-color: var(--accent); }
.chart-tool-btn.active { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }
.chart-tool-btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.chart-tool-btn.primary:hover { background: #0f9b8e; }

#chart-canvas {
  width: 100%;
  height: auto;
  display: block;
  background: #0f1521;
  border-radius: 8px;
  touch-action: none;
  cursor: crosshair;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,0.04);
}

.readout-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 10px;
  padding: 8px;
  background: var(--bg);
  border-radius: 6px;
  border: 1px solid var(--border);
}
.readout-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  background: linear-gradient(180deg, #232c42, #1a2034);
  border: 1px solid #3a4565;
  border-radius: 999px;
  font-size: 0.82rem;
  color: #cbd5e1;
  font-family: var(--mono);
  font-weight: 600;
}
.readout-badge strong { color: #ffffff; font-weight: 800; margin: 0 4px; font-size: 0.92rem; }
.rb-dot {
  width: 8px; height: 8px; border-radius: 50%;
  flex-shrink: 0;
}

.ctx-menu {
  position: absolute;
  z-index: 100;
  min-width: 160px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 4px 0;
  box-shadow: 0 8px 24px rgba(0,0,0,.4);
}
.ctx-item {
  display: block;
  width: 100%;
  padding: 8px 16px;
  border: none;
  background: transparent;
  color: var(--text);
  font-size: 0.82rem;
  text-align: left;
  cursor: pointer;
  transition: background .12s;
}
.ctx-item:hover { background: var(--accent-lo); color: var(--accent); }

/* Info panel (right column) */
.info-panel {
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-width: 0;
}
.info-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
}
.info-card-title {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 10px;
}

.point-select {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 4px 8px;
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 0.78rem;
  cursor: pointer;
}

/* Property grid */
.prop-grid { display: flex; flex-direction: column; gap: 6px; }
.prop-row {
  display: grid;
  grid-template-columns: 110px 1fr 50px;
  align-items: center;
  gap: 6px;
  padding: 4px 6px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
}
.prop-label { font-size: 0.78rem; color: var(--text-dim); }
.prop-input {
  border: none;
  background: transparent;
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.82rem;
  font-weight: 700;
  text-align: right;
  outline: none;
  width: 100%;
  -moz-appearance: textfield;
}
.prop-input::-webkit-outer-spin-button,
.prop-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.prop-input:focus { color: var(--green); }
.prop-input:read-only { color: var(--text-dim); }
.prop-unit { font-size: 0.72rem; color: var(--text-dim); font-weight: 600; }

.solver-hint {
  margin-top: 8px;
  font-size: 0.72rem;
  color: var(--text-dim);
  font-style: italic;
  line-height: 1.4;
}
.solver-hint.warn { color: var(--gold); font-style: normal; }

/* Slider rows */
.slider-row {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  margin-bottom: 6px;
}
.sim-slider-label {
  flex-shrink: 0;
  min-width: 70px;
  font-size: 0.78rem;
  color: var(--text-dim);
  font-weight: 600;
}
.sim-slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  background: rgba(255,255,255,.12);
  border-radius: 3px;
  outline: none;
  border: 1px solid rgba(255,255,255,.1);
  min-width: 60px;
}
.sim-slider::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 3px;
  background: linear-gradient(to right, var(--accent-lo), rgba(255,255,255,.12));
}
.sim-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px; height: 18px;
  margin-top: -6px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  box-shadow: 0 0 8px var(--accent-lo);
  border: 2px solid rgba(255,255,255,.2);
}
.sim-slider::-moz-range-track {
  height: 6px;
  border-radius: 3px;
  background: linear-gradient(to right, var(--accent-lo), rgba(255,255,255,.12));
  border: none;
}
.sim-slider::-moz-range-thumb {
  width: 16px; height: 16px;
  border: 2px solid rgba(255,255,255,.2);
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
}

/* Stepper */
.stepper {
  display: flex;
  align-items: center;
  gap: 0;
  min-width: 130px;
  flex-shrink: 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg);
  height: 36px;
}
.stepper-btn {
  width: 36px; height: 36px;
  border: none;
  background: var(--surface2);
  color: var(--text-dim);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background .15s, color .15s;
  flex-shrink: 0;
}
.stepper-btn:hover { background: var(--accent-lo); color: var(--text); }
.stepper-btn:active { background: var(--accent); color: #fff; }
.stepper-val {
  flex: 1;
  font-family: var(--mono);
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--accent);
  padding: 0 6px;
  white-space: nowrap;
  text-align: center;
  line-height: 36px;
  cursor: pointer;
}
.stepper-val:hover { background: rgba(20,184,166,0.07); }
.stepper-input {
  flex: 1;
  border: none;
  background: transparent;
  color: var(--green);
  font-family: var(--mono);
  font-size: 0.82rem;
  font-weight: 700;
  text-align: center;
  outline: none;
  height: 36px;
  -moz-appearance: textfield;
  padding: 0 6px;
}
.stepper-input::-webkit-outer-spin-button,
.stepper-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.stepper-unit {
  font-size: 0.7rem;
  color: var(--text-dim);
  font-weight: 600;
  padding-right: 8px;
  white-space: nowrap;
}

.warn-line {
  margin-top: 8px;
  padding: 6px 8px;
  background: rgba(245,200,66,.08);
  border: 1px solid rgba(245,200,66,.3);
  border-radius: 6px;
  font-size: 0.72rem;
  color: var(--gold);
  line-height: 1.4;
}

/* Process tabs */
.proc-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-bottom: 10px;
}
.proc-tab {
  padding: 5px 10px;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text-dim);
  font-size: 0.74rem;
  font-weight: 600;
  border-radius: 6px;
  cursor: pointer;
}
.proc-tab:hover { color: var(--text); border-color: var(--accent); }
.proc-tab.active { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }
.proc-panel { font-size: 0.78rem; color: var(--text-dim); line-height: 1.5; }
.proc-panel .proc-result {
  margin-top: 8px;
  padding: 8px;
  background: var(--bg);
  border-radius: 6px;
  border: 1px solid var(--border);
  font-family: var(--mono);
  font-size: 0.76rem;
}
.proc-panel .proc-result strong { color: var(--accent); }

.load-readout {
  margin-top: 6px;
  padding: 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--text-dim);
  line-height: 1.6;
}
.load-readout strong { color: var(--text); }
.load-readout .lr-row { display: flex; justify-content: space-between; }
.load-readout .lr-row span:first-child { color: var(--text-dim); }

/* Learn panel */
.learn-panel {
  margin-top: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
}
.learn-panel summary {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  user-select: none;
}
.learn-panel-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 22px; height: 22px;
  background: var(--accent-lo);
  color: var(--accent);
  border-radius: 50%;
  font-size: 0.8rem;
  font-weight: 800;
}
.learn-panel-body {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text);
}
.learn-panel-body p { margin-bottom: 8px; }
.learn-panel-body .eq-block {
  padding: 10px 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  margin: 8px 0;
}

/* Calc modal */
.btn { padding: 8px 14px; border-radius: 6px; font-size: 0.85rem; font-weight: 600; cursor: pointer; border: 1px solid var(--border); transition: all .15s; }
.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-primary:hover { background: #0f9b8e; }
.btn-ghost { background: transparent; color: var(--text-dim); }
.btn-ghost:hover { color: var(--accent); border-color: var(--accent); }

#btn-show-calc { margin-top: 10px; }

.calc-modal {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.7);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.calc-modal-inner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  max-width: 700px;
  width: 100%;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
}
.calc-modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
}
.calc-modal-header h3 { color: var(--accent); font-size: 1rem; }
.calc-close {
  background: none;
  border: none;
  color: var(--text-dim);
  font-size: 1.6rem;
  cursor: pointer;
  line-height: 1;
}
.calc-close:hover { color: var(--red); }
.calc-modal-body {
  padding: 18px;
  overflow-y: auto;
  font-size: 0.85rem;
  line-height: 1.7;
}
.calc-modal-body .calc-step {
  padding: 10px;
  background: var(--bg);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
  margin-bottom: 10px;
}
.calc-modal-body .calc-step-title { font-weight: 700; color: var(--accent); margin-bottom: 4px; }

/* Explore */
.explore-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}
.explore-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}
.explore-tab {
  padding: 8px 14px;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text-dim);
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: 6px;
  cursor: pointer;
}
.explore-tab:hover { color: var(--text); }
.explore-tab.active { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }

.explore-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
}
.explore-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
}
.explore-card h4 {
  color: var(--accent);
  font-size: 0.95rem;
  margin-bottom: 8px;
}
.explore-card p { font-size: 0.82rem; line-height: 1.6; color: var(--text); margin-bottom: 6px; }
.explore-card .ec-formula {
  display: block;
  padding: 6px 8px;
  margin: 8px 0;
  background: var(--surface2);
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--green);
}
.explore-card .ec-note {
  display: block;
  margin-top: 8px;
  padding: 6px 8px;
  background: var(--accent-lo);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
  font-size: 0.76rem;
  color: var(--text);
  font-style: italic;
}

/* Practice / Quiz */
.practice-panel, .quiz-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  max-width: 720px;
  margin: 0 auto;
}
.practice-header, .quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 14px;
  font-size: 0.85rem;
  color: var(--text-dim);
}
.practice-header strong, .quiz-header strong { color: var(--accent); font-family: var(--mono); }
.practice-question, .quiz-question {
  padding: 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 14px;
}
.practice-input {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-bottom: 12px;
}
.practice-input input {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 10px;
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 0.95rem;
  outline: none;
}
.practice-input input:focus { border-color: var(--accent); }
.practice-input span { color: var(--text-dim); font-size: 0.85rem; min-width: 50px; }
.practice-feedback { padding: 10px; border-radius: 6px; font-size: 0.85rem; min-height: 20px; }
.practice-feedback.ok { background: rgba(61,220,132,.1); border: 1px solid var(--green); color: var(--green); }
.practice-feedback.err { background: rgba(255,85,85,.1); border: 1px solid var(--red); color: var(--red); }

.quiz-options {
  display: grid;
  gap: 8px;
  margin-bottom: 12px;
}
.quiz-option {
  padding: 12px 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 0.9rem;
  cursor: pointer;
  text-align: left;
  transition: all .15s;
}
.quiz-option:hover { border-color: var(--accent); background: var(--surface2); }
.quiz-option.correct { background: rgba(61,220,132,.15); border-color: var(--green); color: var(--green); }
.quiz-option.wrong { background: rgba(255,85,85,.15); border-color: var(--red); color: var(--red); }
.quiz-option:disabled { cursor: default; }

.quiz-result {
  padding: 18px;
  background: var(--bg);
  border: 1px solid var(--accent);
  border-radius: 8px;
  text-align: center;
}
.quiz-result h3 { color: var(--accent); font-size: 1.2rem; margin-bottom: 8px; }
.quiz-stars { font-size: 1.6rem; color: var(--gold); margin: 10px 0; letter-spacing: 4px; }

/* User guide */
.user-guide {
  margin-top: 30px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}
.user-guide h2 {
  color: var(--accent);
  font-size: 1.2rem;
  margin-bottom: 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border);
}
.user-guide details {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 8px;
}
.user-guide summary {
  padding: 12px 14px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.92rem;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 10px;
  user-select: none;
}
.user-guide summary:hover { color: var(--accent); }
.guide-section-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px; height: 24px;
  background: var(--accent-lo);
  color: var(--accent);
  border-radius: 50%;
  font-size: 0.8rem;
  font-weight: 800;
  font-family: var(--mono);
}
.user-guide details[open] { background: var(--surface2); }
.user-guide details p,
.user-guide details ul {
  padding: 0 14px 12px 48px;
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text);
}
.guide-list { list-style: disc; }
.guide-list li { margin-bottom: 8px; }

/* SEO Article */
.seo-article {
  margin-top: 30px;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  line-height: 1.7;
}
.seo-article h2 {
  color: var(--accent);
  font-size: 1.3rem;
  margin-bottom: 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border);
}
.seo-article h3 {
  color: var(--text);
  font-size: 1.05rem;
  margin: 18px 0 8px;
}
.seo-article p { font-size: 0.9rem; margin-bottom: 10px; }
.seo-article a { color: var(--accent); text-decoration: none; }
.seo-article a:hover { text-decoration: underline; }
.seo-article strong { color: var(--text); }
.seo-article em { color: var(--accent); font-style: italic; }

/* Responsive */
@media (max-width: 1000px) {
  .psy-layout {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  #app { padding: 12px 14px 30px; }
  .tool-header h1 { font-size: 1.5rem; }
  .subtitle { font-size: 0.88rem; }
  .controls-bar { flex-direction: column; align-items: stretch; }
  .pill-tabs { width: 100%; justify-content: center; }
  .pill-tab { padding: 8px 12px; font-size: 0.82rem; }
  .chart-toolbar { gap: 6px; }
  .chart-tool-btn { padding: 5px 8px; font-size: 0.72rem; }
  .info-card { padding: 12px; }
  .prop-row { grid-template-columns: 90px 1fr 40px; }
  .prop-label { font-size: 0.74rem; }
  .readout-badge { font-size: 0.72rem; padding: 3px 8px; }
}

@media (max-width: 500px) {
  #app { padding: 10px 10px 24px; }
  .tool-header h1 { font-size: 1.3rem; }
  .subtitle { font-size: 0.82rem; }
  .pill-tab { padding: 6px 10px; font-size: 0.78rem; }
  .unit-toggle { width: 100%; justify-content: center; }
  .chart-tool-btn { padding: 4px 6px; font-size: 0.68rem; }
  .info-card-title { font-size: 0.78rem; }
  .prop-row { grid-template-columns: 80px 1fr 36px; padding: 3px 4px; }
  .prop-label { font-size: 0.7rem; }
  .prop-input { font-size: 0.78rem; }
  .stepper { min-width: 110px; }
  .stepper-val { font-size: 0.74rem; }
  .sim-slider-label { min-width: 60px; font-size: 0.74rem; }
  .seo-article { padding: 16px; }
  .seo-article h2 { font-size: 1.1rem; }
  .user-guide details p,
  .user-guide details ul { padding-left: 14px; }
}

/* ═══ v4 UPGRADES ═══ */

/* Cursor feedback */
#chart-canvas { cursor: crosshair; }
#chart-canvas.dragging { cursor: grabbing; }
#chart-canvas.over-point { cursor: grab; }

/* Preset bar */
.preset-bar {
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
  margin-bottom: 8px; padding: 6px 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.preset-label { font-size: 0.78rem; color: var(--text-dim); font-weight: 600; }
.preset-select {
  flex: 1; min-width: 180px;
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 10px;
  border-radius: 6px;
  font-size: 0.82rem;
  font-family: var(--font);
  cursor: pointer;
  outline: none;
  min-height: 36px;
}
.preset-select:focus { border-color: var(--accent); }

/* Touch target minimums */
.chart-tool-btn { min-height: 36px; }
.proc-tab { min-height: 32px; }
.unit-btn, .pill-tab { min-height: 36px; }

/* First-time hint */
.chart-hint {
  margin-top: 8px;
  padding: 10px 36px 10px 14px;
  background: linear-gradient(180deg, rgba(20,184,166,0.14), rgba(20,184,166,0.06));
  border: 1px solid rgba(20,184,166,0.35);
  border-radius: 8px;
  font-size: 0.82rem;
  color: var(--text);
  position: relative;
  line-height: 1.5;
}
.chart-hint strong { color: var(--accent); }
.chart-hint.hidden { display: none; }
.hint-close {
  position: absolute; top: 6px; right: 8px;
  background: none; border: none;
  color: var(--text-dim);
  font-size: 1.2rem; line-height: 1;
  cursor: pointer; padding: 4px 8px;
}
.hint-close:hover { color: var(--red); }

/* Ice phase notice */
.ice-notice {
  margin-top: 8px;
  padding: 8px 12px;
  background: rgba(140,200,255,0.08);
  border: 1px solid rgba(140,200,255,0.3);
  border-radius: 6px;
  font-size: 0.78rem;
  color: #9bd6ff;
}

/* Industrial Modules section */
.indust-modules {
  margin-top: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
}
.indust-title {
  color: var(--accent);
  font-size: 1.1rem;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.indust-tabs {
  display: flex; flex-wrap: wrap; gap: 4px;
  margin-bottom: 14px;
}
.indust-tab {
  padding: 8px 14px;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text-dim);
  font-size: 0.84rem;
  font-weight: 600;
  border-radius: 6px;
  cursor: pointer;
  min-height: 36px;
}
.indust-tab:hover { color: var(--text); }
.indust-tab.active { background: var(--accent-lo); color: var(--accent); border-color: var(--accent); }
.indust-desc {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-bottom: 12px;
  line-height: 1.55;
}

/* Coil grid */
.coil-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 10px;
  margin-bottom: 14px;
}
.coil-block {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
}
.coil-block h4 { color: var(--accent); font-size: 0.85rem; margin-bottom: 8px; }
.coil-block label, .tower-grid label, .evap-grid label, .tl-controls label {
  display: flex; align-items: center; gap: 6px;
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-bottom: 6px;
}
.coil-block label > input, .tower-grid label > input, .evap-grid label > input, .tl-controls label > input,
.evap-grid select {
  flex: 1; min-width: 60px;
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--accent);
  padding: 5px 7px;
  border-radius: 5px;
  font-family: var(--mono);
  font-size: 0.82rem;
  font-weight: 700;
  outline: none;
  -moz-appearance: textfield;
  min-height: 32px;
  text-align: right;
}
.coil-block label > input::-webkit-inner-spin-button,
.tower-grid label > input::-webkit-inner-spin-button,
.evap-grid label > input::-webkit-inner-spin-button,
.tl-controls label > input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.coil-block label .u, .tower-grid label .u, .evap-grid label .u, .tl-controls label .u {
  font-size: 0.7rem; color: var(--text-dim); min-width: 28px;
}

.tower-grid, .evap-grid, .tl-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 8px 14px;
  align-items: end;
  margin-bottom: 14px;
}

.coil-results, .tower-results, .evap-results, .tl-results {
  padding: 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.7;
}
.coil-results:empty, .tower-results:empty, .evap-results:empty, .tl-results:empty { display: none; }
.coil-results .rs-row, .tower-results .rs-row, .evap-results .rs-row, .tl-results .rs-row {
  display: flex; justify-content: space-between; gap: 12px;
}
.coil-results .rs-row span:first-child,
.tower-results .rs-row span:first-child,
.evap-results .rs-row span:first-child,
.tl-results .rs-row span:first-child { color: var(--text-dim); }
.coil-results .rs-row strong,
.tower-results .rs-row strong,
.evap-results .rs-row strong,
.tl-results .rs-row strong { color: var(--text); }
.coil-results .rs-section,
.tower-results .rs-section { margin-top: 10px; color: var(--accent); font-weight: 700; font-size: 0.78rem; }

#timeline-canvas {
  width: 100%;
  max-width: 100%;
  height: auto;
  display: block;
  background: #0a0e15;
  border-radius: 6px;
  border: 1px solid var(--border);
  margin: 10px 0;
}

/* Custom Point Modal rows */
.cp-row {
  display: grid;
  grid-template-columns: 100px 1fr 50px;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
}
.cp-row > span:first-child { color: var(--text-dim); font-size: 0.84rem; }
.cp-row > input, .cp-row > select {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--accent);
  padding: 7px 10px;
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 0.88rem;
  outline: none;
  font-weight: 700;
  min-height: 36px;
}
.cp-row > input:focus, .cp-row > select:focus { border-color: var(--accent); }
.cp-u { font-size: 0.78rem; color: var(--text-dim); }
.cp-error {
  padding: 8px 10px;
  background: rgba(255,85,85,0.1);
  border: 1px solid var(--red);
  border-radius: 6px;
  color: var(--red);
  font-size: 0.82rem;
}

/* Mobile tweaks */
@media (max-width: 500px) {
  .coil-grid, .tower-grid, .evap-grid, .tl-controls { grid-template-columns: 1fr; }
  .indust-tab { padding: 6px 10px; font-size: 0.78rem; }
  .preset-select { font-size: 0.78rem; }
  .cp-row { grid-template-columns: 80px 1fr 40px; }
}

/* ═══ v5 CONTRAST UPGRADES ═══ */

/* Chart legend */
.chart-legend {
  display: flex; flex-wrap: wrap; gap: 4px 14px;
  margin-top: 8px; padding: 6px 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 0.76rem;
  color: #cbd5e1;
}
.lg-item {
  display: inline-flex; align-items: center; gap: 6px;
  font-weight: 600;
}
.lg-swatch {
  width: 14px; height: 3px; border-radius: 2px;
  display: inline-block;
}
.lg-item.dim { opacity: 0.35; }

/* Brighter overlay button active state */
.chart-tool-btn.active {
  background: linear-gradient(180deg, #14b8a6, #0f9b8e);
  color: #ffffff;
  border-color: #14b8a6;
  box-shadow: 0 0 0 1px rgba(20,184,166,0.4), 0 2px 8px rgba(20,184,166,0.35);
}

/* Brighter accent color tokens for readability */
.info-card-title { color: #5eead4; }
.prop-input { color: #5eead4; }
.prop-input:focus { color: #6ee7b7; }
.stepper-val { color: #5eead4; }

/* Mode tab inactive — better contrast */
.pill-tab { color: #94a3b8; }
.pill-tab:hover { color: #f1f5f9; }