/* Copyright (c) 2026 Mustafa Uzumeri. All rights reserved. */

/* ============================================================
   TOKENS & RESET
   ============================================================ */
:root {
  --bg:           #0a0d12;
  --bg-card:      #111620;
  --bg-card-2:    #161c28;
  --border:       rgba(255,255,255,0.07);
  --border-hover: rgba(255,255,255,0.14);

  --text:         #e8eaf0;
  --text-muted:   #7a8099;
  --text-dim:     #4a5068;

  --burden:       #f97316;   /* orange — the cost */
  --burden-dim:   rgba(249,115,22,0.12);
  --burden-glow:  rgba(249,115,22,0.3);

  --save:         #14b8a6;   /* teal — the relief */
  --save-dim:     rgba(20,184,166,0.12);
  --save-glow:    rgba(20,184,166,0.3);

  --accent:       #6366f1;   /* indigo — UI accents */
  --accent-dim:   rgba(99,102,241,0.15);

  --radius:       12px;
  --radius-lg:    18px;
  --shadow:       0 4px 24px rgba(0,0,0,0.4);

  --mono:         'JetBrains Mono', monospace;
  --sans:         'Inter', system-ui, sans-serif;
}

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

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ============================================================
   HEADER
   ============================================================ */
.app-header {
  background: rgba(10,13,18,0.95);
  border-bottom: 1px solid var(--border);
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  flex-wrap: wrap;
}

.back-link {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.85rem;
  white-space: nowrap;
  transition: color 0.2s;
}
.back-link:hover { color: var(--text); }

.header-title h1 {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}
.header-sub {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.1rem;
}

/* ============================================================
   CLASSROOM SETUP CONFIG BAR
   Persistent strip between the app header and the tab navigation.
   Holds the four parameters shared across all calculator tabs.
   ============================================================ */
.config-bar {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  padding: 0.75rem 1.5rem;
  overflow: hidden; /* never let this strip widen the page */
  width: 100%;
  box-sizing: border-box;
}
.config-bar-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 1.25rem;
}
.config-bar-label {
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  white-space: nowrap;
  flex-shrink: 0;
}
.config-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem 1.25rem;
  flex: 1;
}
.config-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.config-item label {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--text-muted);
  white-space: nowrap;
  min-width: 80px;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}
.config-item input[type="range"] {
  flex: 1;
  min-width: 0; /* override browser default ~129px minimum */
  height: 3px;
  width: 0;    /* let flex grow handle width, not intrinsic size */
}
.config-output {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--text);
  background: var(--bg-card-2);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  min-width: 56px;
  text-align: center;
  white-space: nowrap;
}

/* In-panel context notes that echo the shared config value */
.config-context {
  font-size: 0.78rem;
  color: var(--text-dim);
  line-height: 1.5;
  margin-bottom: 1.5rem;
  padding: 0.5rem 0.75rem;
  background: var(--bg-card-2);
  border-radius: var(--radius);
  border-left: 2px solid var(--accent);
}
.config-echo {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--accent);
  font-weight: 600;
}

@media (max-width: 860px) {
  .config-bar-label { display: none; }
  .config-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 600px) {
  .app-header { padding: 0.75rem 1rem; gap: 1rem; }
  .header-title h1 { font-size: 0.95rem; }
  .config-bar { padding: 0.6rem 1rem; }
  .config-bar-inner { gap: 0.75rem; }
  .config-grid { gap: 0.5rem 0.75rem; }
  .config-item label { min-width: 52px; font-size: 0.63rem; }
  .config-output { min-width: 44px; font-size: 0.68rem; padding: 0.1rem 0.3rem; }
}
@media (max-width: 480px) {
  .config-grid { grid-template-columns: 1fr; }
  .config-item label { min-width: 100px; width: 100px; font-size: 0.63rem; }
}

/* ============================================================
   TAB NAVIGATION
   ============================================================ */
.tab-nav {
  display: flex;
  gap: 0;
  padding: 0 1.5rem;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  overflow-x: auto;
  scrollbar-width: none;
  width: 100%;
  max-width: 100%;
  box-sizing: border-box;
}
.tab-nav::-webkit-scrollbar { display: none; }

.tab-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 1rem 1.25rem;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--text-muted);
  font-family: var(--sans);
  font-size: 0.88rem;
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
  transition: color 0.2s, border-color 0.2s;
  position: relative;
}
.tab-btn:hover:not(:disabled) { color: var(--text); }
.tab-btn.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}
.tab-btn.coming-soon {
  opacity: 0.5;
  cursor: not-allowed;
}
.badge {
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.15rem 0.45rem;
  background: var(--accent-dim);
  color: var(--accent);
  border-radius: 999px;
  letter-spacing: 0.02em;
}

/* ============================================================
   MAIN LAYOUT
   ============================================================ */
.app-main { 
  max-width: 1100px; 
  margin: 0 auto; 
  padding: 2rem 1.5rem 4rem; 
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

.panel-intro {
  margin-bottom: 2rem;
}
.panel-lede {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 680px;
  line-height: 1.7;
  border-left: 3px solid var(--accent);
  padding-left: 1rem;
}

/* ============================================================
   CARDS
   ============================================================ */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow);
}
.card-title {
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text);
  margin-bottom: 1.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border);
}

.calc-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

@media (max-width: 720px) {
  .calc-layout { grid-template-columns: 1fr; }
}

/* ============================================================
   INPUT CONTROLS
   ============================================================ */
.input-group {
  margin-bottom: 1.5rem;
}
.input-group:last-child { margin-bottom: 0; }

.input-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.6rem;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}

input[type="range"] {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 4px;
  background: var(--bg-card-2);
  border-radius: 999px;
  outline: none;
  cursor: pointer;
  transition: background 0.2s;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
  box-shadow: 0 0 8px var(--accent);
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s;
}
input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
  box-shadow: 0 0 14px var(--accent);
}
input[type="range"]:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  border-radius: 4px;
}

.slider-output {
  font-family: var(--mono);
  font-size: 0.88rem;
  color: var(--text);
  background: var(--bg-card-2);
  padding: 0.25rem 0.6rem;
  border-radius: 6px;
  min-width: 80px;
  text-align: center;
  white-space: nowrap;
}

.input-hint {
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
  line-height: 1.5;
}

.divider-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin: 1.5rem 0 1rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.divider-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

.method-tag {
  font-size: 0.7rem;
  font-weight: 700;
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.batch-tag { background: var(--burden-dim); color: var(--burden); }
.micro-tag { background: var(--save-dim); color: var(--save); }

/* ============================================================
   RESULTS — ASYMMETRY CALCULATOR
   ============================================================ */
.cost-note {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  font-style: italic;
}

.metric-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.metric {
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  transition: border-color 0.3s;
}
.metric.highlight-metric {
  border-color: var(--burden);
  background: var(--burden-dim);
  box-shadow: 0 0 20px var(--burden-glow);
}
.metric-label {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.4rem;
}
.metric-value {
  font-family: var(--mono);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--burden);
  line-height: 1.2;
  transition: all 0.3s;
}
.metric-sub {
  font-size: 0.72rem;
  color: var(--text-dim);
  margin-top: 0.25rem;
}

.equivalence-block {
  background: var(--burden-dim);
  border: 1px solid rgba(249,115,22,0.2);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 1rem;
  text-align: center;
}
.equiv-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.5rem;
}
.equiv-value {
  font-family: var(--mono);
  font-size: 2rem;
  font-weight: 900;
  color: var(--burden);
  line-height: 1.1;
  transition: all 0.3s;
}
.equiv-explanation {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
  line-height: 1.5;
}

/* ============================================================
   RESULTS — OBSERVATION BURDEN
   ============================================================ */
.total-obs {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-card-2);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  margin-bottom: 1.25rem;
}
.total-label {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 600;
}
.total-value {
  font-family: var(--mono);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text);
}

.comparison-table {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 1.25rem;
}
.comparison-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  border-bottom: 1px solid var(--border);
}
.comparison-row:last-child { border-bottom: none; }
.comparison-row > div {
  padding: 0.6rem 0.85rem;
  font-size: 0.85rem;
}
.comparison-row.header-row > div {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-dim);
  background: var(--bg-card-2);
}
.row-label { color: var(--text-muted); }
.col-batch {
  font-family: var(--mono);
  font-weight: 600;
  color: var(--burden);
  background: var(--burden-dim);
}
.col-micro {
  font-family: var(--mono);
  font-weight: 600;
  color: var(--save);
  background: var(--save-dim);
}

.savings-block {
  background: var(--save-dim);
  border: 1px solid rgba(20,184,166,0.25);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 1rem;
  text-align: center;
  box-shadow: 0 0 20px var(--save-glow);
}
.savings-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.5rem;
}
.savings-value {
  font-family: var(--mono);
  font-size: 2rem;
  font-weight: 900;
  color: var(--save);
  line-height: 1.1;
  transition: all 0.3s;
}
.savings-sub {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
}

/* ============================================================
   SHARED CALLOUT
   ============================================================ */
.insight-callout {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
  padding: 0.75rem 1rem;
  border-left: 2px solid var(--border-hover);
  background: var(--bg-card-2);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-style: italic;
}

/* ============================================================
   EXPLAINER BLOCK
   ============================================================ */
.explainer {
  margin-top: 1.5rem;
}
.explainer h3 {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 1rem;
}
.explainer p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 0.75rem;
}
.explainer p:last-child { margin-bottom: 0; }
.explainer-source {
  font-size: 0.78rem !important;
  color: var(--text-dim) !important;
  margin-top: 0.5rem;
  font-style: italic;
}

/* ============================================================
   PREP OVERHEAD TAB SPECIFIC
   ============================================================ */
.prep-year-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.25rem;
}
.prep-year-btn {
  flex: 1;
  padding: 0.5rem 1rem;
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  font-family: var(--sans);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}
.prep-year-btn:hover { color: var(--text); border-color: var(--border-hover); }
.prep-year-btn.active {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--text);
}

.break-even-block {
  background: var(--bg-card-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-top: 1rem;
  text-align: center;
}
.be-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.5rem;
}
.be-value {
  font-family: var(--mono);
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--accent);
  line-height: 1.2;
  transition: all 0.3s;
}
.be-sub {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.4rem;
}

/* dynamic color for micro total cell */
.col-micro.cheaper { color: var(--save); }
.col-micro.pricier { color: var(--burden); }

/* ============================================================
   COMING SOON PANEL
   ============================================================ */
.coming-soon-panel {
  max-width: 560px;
  margin: 4rem auto;
  text-align: center;
}
.cs-icon { font-size: 3.5rem; margin-bottom: 1.5rem; }
.coming-soon-panel h2 {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}
.coming-soon-panel > p {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  line-height: 1.7;
}
.cs-features {
  text-align: left;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.25rem 1.25rem 2.25rem;
  margin-bottom: 1.5rem;
}
.cs-features li {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 0.5rem;
}
.cs-features li:last-child { margin-bottom: 0; }
.cs-note {
  font-size: 0.83rem;
  color: var(--text-dim);
  font-style: italic;
  line-height: 1.6;
}

/* ============================================================
   FOOTER
   ============================================================ */
.app-footer {
  text-align: center;
  padding: 2rem 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 0.82rem;
  line-height: 1.6;
}
.app-footer a { color: var(--text-muted); }
.app-footer a:hover { color: var(--text); }
.footer-note { margin-top: 0.4rem; font-style: italic; }

/* ============================================================
   ANIMATIONS
   ============================================================ */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}
.tab-panel.active {
  animation: fadeIn 0.25s ease;
}

.metric-value, .equiv-value, .savings-value {
  transition: color 0.3s, transform 0.15s;
}
.metric-value.bump, .equiv-value.bump, .savings-value.bump {
  transform: scale(1.08);
}