/* ── Mental Math Koans – Design System ── */

:root {
  /* backgrounds */
  --bg:            #0a0e14;
  --bg-glass:      rgba(22, 27, 34, 0.6);

  /* borders */
  --border:        rgba(48, 54, 61, 0.65);
  --border-subtle: rgba(48, 54, 61, 0.4);

  /* text */
  --text:          #e0e0e0;
  --text-secondary:#a5a5a5;
  --text-muted:    rgba(165,165,165,0.6);

  /* accents */
  --blue:          #58a6ff;
  --green:         #3fb950;
  --orange:        #d29922;
  --red:           #f85149;
  --purple:        #bc8cff;
  --teal:          #39d2c0;

  /* typography */
  --mono: 'JetBrains Mono','Fira Code','Cascadia Code','Consolas',monospace;
  --serif:'Baskerville','Georgia','Times New Roman',serif;
  --sans: 'Helvetica Neue','Helvetica','Arial',sans-serif;

  /* easing */
  --ease-out: cubic-bezier(0.55,0.085,0.68,0.53);
  --spring:   cubic-bezier(0.175,0.885,0.32,1.275);
}

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

html {
  font-size: 18px;
  background: var(--bg);
  color: var(--text);
  scroll-behavior: smooth;
}

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

/* ── Page Layout ── */
.koan-page {
  max-width: 720px;
  margin: 0 auto;
  padding: 4rem 1.5rem 6rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* ── Zen Text (italic serif quote) ── */
.koan-text {
  font-family: var(--serif);
  font-style: italic;
  font-size: 1.15rem;
  color: var(--text-secondary);
  text-align: center;
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.7;
}

.koan-text::before,
.koan-text::after {
  content: '';
  display: block;
  width: 60px;
  height: 1px;
  background: var(--border);
  margin: 1rem auto;
}

/* ── Title ── */
.koan-title {
  font-family: var(--mono);
  font-size: 1.4rem;
  font-weight: 600;
  text-align: center;
  color: var(--text);
  letter-spacing: -0.02em;
}

/* ── Instructions ── */
.koan-instruction {
  font-size: 1rem;
  color: var(--text-secondary);
  text-align: center;
  max-width: 560px;
  margin: 0 auto;
}

/* ── Interactive Panel (glass) ── */
.koan-interactive {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: 1em;
  padding: 1.75rem;
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.03);
}

/* ── Math Display ── */
.math-display {
  font-family: var(--mono);
  font-size: 1.6rem;
  text-align: center;
  padding: 1rem;
  color: var(--text);
  letter-spacing: 0.05em;
}

.math-display .highlight {
  color: var(--blue);
  font-weight: 700;
}

.math-display .step {
  color: var(--green);
}

.math-display .carry {
  color: var(--orange);
  font-size: 0.9em;
}

/* ── Step-by-step reveal ── */
.step-row {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.4s var(--ease-out), transform 0.4s var(--ease-out);
}

.step-row.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Question Card ── */
.koan-question {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: 1em;
  padding: 1.75rem;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.5s var(--ease-out), transform 0.5s var(--ease-out);
}

.koan-question.visible {
  opacity: 1;
  transform: translateY(0);
}

.koan-question p {
  font-size: 1rem;
  margin-bottom: 1rem;
  color: var(--text);
}

/* ── Option Buttons ── */
.koan-options {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.koan-option {
  font-family: var(--mono);
  font-size: 0.85rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
  border-radius: 0.5em;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.koan-option:hover:not(.disabled) {
  color: var(--blue);
  border-color: var(--blue);
  transform: translateY(-1px);
}

.koan-option.correct {
  color: var(--green);
  border-color: var(--green);
  box-shadow: 0 0 12px rgba(63,185,80,0.2);
}

.koan-option.wrong {
  color: var(--red);
  border-color: var(--red);
  box-shadow: 0 0 12px rgba(248,81,73,0.2);
}

.koan-option.disabled {
  opacity: 0.4;
  cursor: default;
  pointer-events: none;
}

/* ── Text Input Answer ── */
.koan-input {
  font-family: var(--mono);
  font-size: 1.2rem;
  padding: 0.6rem 1rem;
  border: 1px solid var(--border);
  border-radius: 0.5em;
  background: rgba(22,27,34,0.8);
  color: var(--text);
  text-align: center;
  width: 120px;
  outline: none;
  transition: border-color 0.2s ease;
}

.koan-input:focus {
  border-color: var(--blue);
}

.koan-input.correct {
  border-color: var(--green);
  box-shadow: 0 0 12px rgba(63,185,80,0.2);
}

.koan-input.wrong {
  border-color: var(--red);
  box-shadow: 0 0 12px rgba(248,81,73,0.15);
}

/* ── Check Button ── */
.koan-btn {
  font-family: var(--mono);
  font-size: 0.85rem;
  padding: 0.5rem 1.2rem;
  border: 1px solid var(--border);
  border-radius: 0.5em;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
}

.koan-btn:hover {
  color: var(--blue);
  border-color: var(--blue);
}

/* ── Feedback ── */
.koan-feedback {
  font-family: var(--mono);
  font-size: 0.85rem;
  margin-top: 0.75rem;
  min-height: 1.2em;
  color: var(--text-muted);
}

.koan-feedback.correct { color: var(--green); }
.koan-feedback.wrong   { color: var(--red); }

/* ── Insight Reveal ── */
.koan-insight {
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: opacity 0.6s var(--ease-out), max-height 0.6s var(--ease-out);
  text-align: center;
}

.koan-insight.visible {
  opacity: 1;
  max-height: 20rem;
}

.insight-label {
  font-family: var(--mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.koan-insight p {
  font-family: var(--serif);
  font-style: italic;
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 1rem;
  line-height: 1.6;
}

.koan-insight a {
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--blue);
  text-decoration: none;
  transition: opacity 0.2s ease;
}

.koan-insight a:hover {
  opacity: 0.8;
}

/* ── Progress Bar (bottom) ── */
.koan-progress {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: rgba(48,54,61,0.3);
  z-index: 100;
}

.koan-progress-fill {
  height: 100%;
  background: var(--green);
  box-shadow: 0 0 8px rgba(63,185,80,0.3);
  transition: width 0.6s var(--ease-out);
}

/* ── Navigation Bar ── */
.nav-bar {
  position: fixed;
  bottom: 14px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 0.75rem;
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: 2em;
  z-index: 101;
}

.nav-arrow {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  text-decoration: none;
  padding: 0.2rem 0.4rem;
  transition: color 0.2s ease;
}

.nav-arrow:hover { color: var(--text); }
.nav-arrow.disabled { opacity: 0.2; pointer-events: none; }

.nav-dots {
  display: flex;
  gap: 0.35rem;
  align-items: center;
}

.nav-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--border);
  transition: all 0.2s ease;
  text-decoration: none;
}

.nav-dot.current {
  width: 8px;
  height: 8px;
  background: var(--blue);
  box-shadow: 0 0 8px rgba(88,166,255,0.4);
}

.nav-dot.visited {
  background: var(--text-muted);
}

a.nav-dot:hover {
  background: var(--blue);
  transform: scale(1.3);
}

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

.fade-in {
  animation: fadeIn 0.5s var(--ease-out) forwards;
}

/* ── Comparison Boxes ── */
.compare-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.compare-box {
  border: 1px solid var(--border);
  border-radius: 0.75em;
  padding: 1.25rem;
  text-align: center;
  cursor: pointer;
  transition: all 0.3s ease;
}

.compare-box:hover {
  border-color: var(--blue);
}

.compare-box.active {
  border-color: var(--green);
  box-shadow: 0 0 16px rgba(63,185,80,0.1);
}

.compare-label {
  font-family: var(--mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

/* ── Practice Area ── */
.practice-problem {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.practice-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin: 0.5rem 0;
  justify-content: center;
}

/* ── Responsive ── */
@media (max-width: 600px) {
  html { font-size: 16px; }
  .koan-page { padding: 2rem 1rem 5rem; }
  .compare-grid { grid-template-columns: 1fr; }
  .math-display { font-size: 1.3rem; }
}