/* ═══════════════════════════════════════════════════════════════
   style.css — Explainable Summary Score
   Design system with full dark / light mode support
═══════════════════════════════════════════════════════════════ */

@import url("https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;600&display=swap");

/* ── CSS Custom Properties ─────────────────────────────────── */

:root,
[data-theme="dark"] {
  --bg: #07071a;
  --bg2: #0d0d24;
  --surface: #12122b;
  --card: #16163a;
  --card-hover: #1c1c48;
  --border: rgba(108, 99, 255, 0.18);
  --border-soft: rgba(255, 255, 255, 0.06);

  --primary: #6c63ff;
  --primary-glow: #6c63ff55;
  --primary-hover: #8179ff;
  --accent: #ff6b9d;
  --accent2: #00d4ff;

  --text: #e8eaf6;
  --text-muted: #8c8fa8;
  --text-dim: #575a75;

  --success: #4ade80;
  --warning: #fbbf24;
  --danger: #f87171;
  --info: #38bdf8;

  --score-good: #4ade80;
  --score-mid: #fbbf24;
  --score-low: #f87171;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.6);
  --glow: 0 0 24px rgba(108, 99, 255, 0.25);
  --glow-lg:
    0 0 60px rgba(108, 99, 255, 0.15), 0 0 120px rgba(0, 212, 255, 0.05);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;

  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg: #f0f2ff;
  --bg2: #e8eaff;
  --surface: #ffffff;
  --card: #ffffff;
  --card-hover: #f5f3ff;
  --border: rgba(108, 99, 255, 0.15);
  --border-soft: rgba(0, 0, 0, 0.07);

  --primary: #5a52e8;
  --primary-glow: #5a52e833;
  --primary-hover: #4840d4;
  --accent: #e04080;
  --accent2: #0ea5e9;

  --text: #1a1a3e;
  --text-muted: #5c5f7a;
  --text-dim: #9497b0;

  --success: #16a34a;
  --warning: #d97706;
  --danger: #dc2626;
  --info: #0284c7;

  --score-good: #16a34a;
  --score-mid: #d97706;
  --score-low: #dc2626;

  --shadow-sm: 0 2px 8px rgba(80, 70, 200, 0.08);
  --shadow-md: 0 8px 32px rgba(80, 70, 200, 0.12);
  --shadow-lg: 0 20px 60px rgba(80, 70, 200, 0.15);
  --glow: 0 0 24px rgba(108, 99, 255, 0.12);
  --glow-lg: 0 0 60px rgba(108, 99, 255, 0.08);
}

/* ── Reset & Base ──────────────────────────────────────────── */

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

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

body {
  font-family: "Inter", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  transition:
    background var(--transition),
    color var(--transition);
  overflow-x: hidden;
}

::selection {
  background: var(--primary);
  color: #fff;
}

/* ── Scrollbar ─────────────────────────────────────────────── */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: var(--bg);
}

::-webkit-scrollbar-thumb {
  background: var(--primary);
  border-radius: 99px;
}

/* ── Typography ────────────────────────────────────────────── */

h1,
h2,
h3,
h4,
h5 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--text);
}

h1 {
  font-size: clamp(2.4rem, 6vw, 4.5rem);
  font-weight: 900;
}

h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
}

h3 {
  font-size: 1.4rem;
}

p {
  color: var(--text-muted);
}

code,
pre {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.88em;
  background: var(--bg2);
  border-radius: var(--radius-sm);
}

/* ── Layout Utilities ──────────────────────────────────────── */

.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 96px 0;
}

.section--sm {
  padding: 64px 0;
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

@media (max-width: 768px) {

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 64px 0;
  }
}

/* ── Navbar ────────────────────────────────────────────────── */

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition:
    background var(--transition),
    box-shadow var(--transition);
}

.navbar.scrolled {
  background: rgba(7, 7, 26, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: var(--shadow-sm);
  border-bottom: 1px solid var(--border-soft);
}

[data-theme="light"] .navbar.scrolled {
  background: rgba(240, 242, 255, 0.85);
}

.navbar__logo {
  font-size: 1.1rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary), var(--accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
  letter-spacing: -0.5px;
}

.navbar__links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.navbar__links a {
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
}

.navbar__links a:hover {
  color: var(--text);
}

.navbar__actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

@media (max-width: 768px) {
  .navbar__links {
    display: none;
  }
}

/* ── Theme Toggle ──────────────────────────────────────────── */

.theme-toggle {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 50%;
  cursor: pointer;
  transition: all var(--transition);
  font-size: 1.1rem;
}

.theme-toggle:hover {
  background: var(--card-hover);
  box-shadow: var(--glow);
  transform: scale(1.05);
}

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

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  border: none;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn--primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-hover));
  color: #fff;
  box-shadow: 0 4px 20px var(--primary-glow);
}

.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px var(--primary-glow);
}

.btn--primary:active {
  transform: translateY(0);
}

.btn--ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.btn--ghost:hover {
  background: var(--card);
  color: var(--text);
  border-color: var(--primary);
}

.btn--sm {
  padding: 8px 16px;
  font-size: 0.85rem;
}

.btn--lg {
  padding: 16px 36px;
  font-size: 1.05rem;
}

/* ── Cards ──────────────────────────────────────────────────── */

.card {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition);
}

.card:hover {
  border-color: var(--border);
  box-shadow: var(--shadow-md), var(--glow);
  transform: translateY(-2px);
}

.card--glass {
  background: rgba(22, 22, 58, 0.6);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
}

[data-theme="light"] .card--glass {
  background: rgba(255, 255, 255, 0.7);
}

/* ── Section Titles ─────────────────────────────────────────── */

.section-title {
  text-align: center;
  margin-bottom: 60px;
}

.section-title h2 {
  margin-bottom: 12px;
}

.section-title p {
  max-width: 560px;
  margin: 0 auto;
}

.badge {
  display: inline-block;
  padding: 4px 14px;
  background: var(--primary-glow);
  color: var(--primary);
  border-radius: 99px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 12px;
  border: 1px solid var(--border);
}

/* ═══════════════════════════════════════════════════════════════
   HERO SECTION
═══════════════════════════════════════════════════════════════ */

.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding: 120px 0 80px;
}

.hero__bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  background:
    radial-gradient(ellipse 80% 60% at 50% 0%,
      rgba(108, 99, 255, 0.18) 0%,
      transparent 70%),
    radial-gradient(ellipse 50% 40% at 80% 60%,
      rgba(0, 212, 255, 0.08) 0%,
      transparent 70%),
    radial-gradient(ellipse 40% 30% at 20% 80%,
      rgba(255, 107, 157, 0.08) 0%,
      transparent 70%);
}

/* Animated grid lines */
.hero__grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(108, 99, 255, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(108, 99, 255, 0.04) 1px, transparent 1px);
  background-size: 60px 60px;
  animation: gridScroll 20s linear infinite;
}

@keyframes gridScroll {
  0% {
    transform: translate(0, 0);
  }

  100% {
    transform: translate(60px, 60px);
  }
}

.hero__content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 780px;
  margin: 0 auto;
}

.hero__tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 18px;
  background: rgba(108, 99, 255, 0.12);
  border: 1px solid rgba(108, 99, 255, 0.25);
  border-radius: 99px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 28px;
  animation: fadeDown 0.8s ease both;
}

.hero__title {
  animation: fadeDown 0.8s 0.1s ease both;
  margin-bottom: 24px;
}

.hero__title .grad {
  background: linear-gradient(135deg,
      var(--primary) 0%,
      var(--accent2) 50%,
      var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 580px;
  margin: 0 auto 40px;
  animation: fadeDown 0.8s 0.2s ease both;
}

.hero__cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeDown 0.8s 0.3s ease both;
}

.hero__stats {
  margin-top: 72px;
  display: flex;
  justify-content: center;
  gap: 56px;
  flex-wrap: wrap;
  animation: fadeDown 0.8s 0.4s ease both;
}

.hero__stat {
  text-align: center;
}

.hero__stat-value {
  font-size: 2.2rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary), var(--accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__stat-label {
  font-size: 0.83rem;
  color: var(--text-dim);
  margin-top: 2px;
}

/* Floating orbs */
.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.25;
  animation: float 8s ease-in-out infinite;
  pointer-events: none;
}

.orb-1 {
  width: 400px;
  height: 400px;
  background: var(--primary);
  top: -100px;
  right: -100px;
  animation-delay: 0s;
}

.orb-2 {
  width: 300px;
  height: 300px;
  background: var(--accent2);
  bottom: 0;
  left: -80px;
  animation-delay: -3s;
}

.orb-3 {
  width: 200px;
  height: 200px;
  background: var(--accent);
  bottom: 80px;
  right: 10%;
  animation-delay: -6s;
}

@keyframes float {

  0%,
  100% {
    transform: translateY(0) rotate(0deg);
  }

  50% {
    transform: translateY(-30px) rotate(5deg);
  }
}

@keyframes fadeDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ═══════════════════════════════════════════════════════════════
   HOW IT WORKS
═══════════════════════════════════════════════════════════════ */

.how-it-works {
  background: var(--bg2);
}

.pipeline {
  display: flex;
  align-items: flex-start;
  gap: 0;
  position: relative;
}

.pipeline::before {
  content: "";
  position: absolute;
  top: 36px;
  left: calc(33.3% - 12px);
  right: calc(33.3% - 12px);
  height: 2px;
  background: linear-gradient(90deg, var(--primary), var(--accent2));
  border-radius: 99px;
}

.pipeline-step {
  flex: 1;
  text-align: center;
  padding: 0 16px;
  position: relative;
}

.pipeline-step__icon {
  width: 72px;
  height: 72px;
  background: linear-gradient(135deg, var(--primary), var(--accent2));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  margin: 0 auto 20px;
  box-shadow: var(--glow);
  position: relative;
  z-index: 1;
}

.pipeline-step__num {
  position: absolute;
  top: -8px;
  right: -8px;
  width: 22px;
  height: 22px;
  background: var(--accent);
  color: #fff;
  border-radius: 50%;
  font-size: 0.7rem;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pipeline-step h3 {
  font-size: 1.05rem;
  margin-bottom: 8px;
}

.pipeline-step p {
  font-size: 0.88rem;
}

@media (max-width: 768px) {
  .pipeline {
    flex-direction: column;
    gap: 32px;
  }

  .pipeline::before {
    display: none;
  }
}

/* ═══════════════════════════════════════════════════════════════
   DEMO SECTION
═══════════════════════════════════════════════════════════════ */

.demo {
  position: relative;
}

.demo__layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}

@media (max-width: 900px) {
  .demo__layout {
    grid-template-columns: 1fr;
  }
}

/* Form card */
.form__group {
  margin-bottom: 20px;
}

.form__label {
  display: block;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.form__input,
.form__textarea,
.form__select {
  width: 100%;
  padding: 14px 16px;
  background: var(--bg2);
  border: 1.5px solid var(--border-soft);
  border-radius: var(--radius-md);
  color: var(--text);
  font-family: inherit;
  font-size: 0.95rem;
  line-height: 1.5;
  transition:
    border-color var(--transition),
    box-shadow var(--transition);
  resize: vertical;
}

.form__input:focus,
.form__textarea:focus,
.form__select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.form__textarea {
  min-height: 120px;
}

.form__row {
  display: flex;
  gap: 12px;
}

.form__row>* {
  flex: 1;
}

/* ── Score Display ─────────────────────────────────────────── */

.result-panel {
  display: none;
  animation: slideUp 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.result-panel.visible {
  display: block;
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.score-display {
  text-align: center;
  padding: 28px 24px;
  background: var(--card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-soft);
  margin-bottom: 20px;
  position: relative;
  overflow: hidden;
}

.score-display::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--accent2));
}

.score-display__value {
  font-size: 4rem;
  font-weight: 900;
  line-height: 1;
  margin-bottom: 4px;
}

.score-display__label {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-bottom: 20px;
}

.score-bar {
  height: 10px;
  background: var(--bg2);
  border-radius: 99px;
  overflow: hidden;
  margin-bottom: 8px;
}

.score-bar__fill {
  height: 100%;
  border-radius: 99px;
  transform-origin: left;
  transform: scaleX(0);
  transition: transform 1s cubic-bezier(0.4, 0, 0.2, 1);
}

.score-bar__fill.animate {
  transform: scaleX(1);
}

/* ── Plain English Explanation ─────────────────────────────── */

.explanation-card {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: 20px;
}

.explanation-card__header {
  background: linear-gradient(135deg,
      rgba(108, 99, 255, 0.15),
      rgba(0, 212, 255, 0.08));
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-soft);
  display: flex;
  align-items: center;
  gap: 10px;
}

.explanation-card__header h3 {
  font-size: 1rem;
  font-weight: 700;
}

.explanation-card__header .part-badge {
  padding: 3px 10px;
  border-radius: 99px;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  background: var(--primary-glow);
  color: var(--primary);
  border: 1px solid var(--border);
}

.explanation-card__body {
  padding: 20px 24px;
}

.explanation-section {
  display: flex;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--border-soft);
}

.explanation-section:last-child {
  border-bottom: none;
}

.explanation-section--sub {
  padding-left: 24px;
  opacity: 0.82;
}

.explanation-section__icon {
  font-size: 1.2rem;
  flex-shrink: 0;
  margin-top: 1px;
}

.explanation-section__text {
  font-size: 0.92rem;
  color: var(--text);
  line-height: 1.6;
}

.explanation-section__text strong {
  color: var(--primary);
}

.tips-box {
  background: rgba(108, 99, 255, 0.07);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  margin-top: 12px;
}

.tips-box__title {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.tips-box ul {
  padding-left: 20px;
}

.tips-box li {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 6px;
}

/* ── SHAP Chart Card ───────────────────────────────────────── */

.shap-card {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: 20px;
}

.shap-card__header {
  background: linear-gradient(135deg,
      rgba(0, 212, 255, 0.12),
      rgba(108, 99, 255, 0.08));
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-soft);
  display: flex;
  align-items: center;
  gap: 10px;
}

.shap-card__body {
  padding: 20px 24px;
}

/* SHAP bar rows */
.shap-row {
  display: grid;
  grid-template-columns: 160px 1fr 72px;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
}

.shap-row__label {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-muted);
  text-align: right;
}

.shap-row__bar-wrap {
  position: relative;
  height: 22px;
  background: var(--bg2);
  border-radius: 4px;
  overflow: visible;
}

.shap-row__mid {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 2px;
  background: var(--border);
  transform: translateX(-50%);
}

.shap-row__fill {
  position: absolute;
  top: 3px;
  bottom: 3px;
  border-radius: 4px;
  transition:
    width 1s cubic-bezier(0.4, 0, 0.2, 1),
    left 1s cubic-bezier(0.4, 0, 0.2, 1);
}

.shap-row__fill--pos {
  background: linear-gradient(90deg, #4ade80, #22c55e);
}

.shap-row__fill--neg {
  background: linear-gradient(90deg, #f87171, #ef4444);
}

.shap-row__value {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.78rem;
  font-weight: 600;
  text-align: left;
}

/* ── Anchors display ──────────────────────────────────────── */

.anchors-display {
  margin-bottom: 20px;
}

.anchor-tag {
  display: inline-block;
  padding: 4px 12px;
  margin: 4px;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 99px;
  font-size: 0.78rem;
  color: var(--text-muted);
  transition: all var(--transition);
}

.anchor-tag:hover {
  background: var(--primary-glow);
  border-color: var(--primary);
  color: var(--primary);
}

/* ── Two-Stage Score Breakdown ─────────────────────────────── */

#stage-breakdown {
  margin-top: 16px;
}

.stage-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: center;
  margin-bottom: 12px;
}

.stage-item {
  background: var(--bg2);
  border: 1.5px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 14px 16px;
  text-align: center;
  transition: all var(--transition);
  position: relative;
}

.stage-item--winner {
  border-color: var(--primary);
  background: var(--primary-glow);
  box-shadow: var(--glow);
}

.stage-item__icon {
  font-size: 1.4rem;
  margin-bottom: 4px;
}

.stage-item__label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
  margin-bottom: 6px;
}

.stage-item__score {
  font-size: 1.6rem;
  font-weight: 800;
  line-height: 1;
  margin-bottom: 4px;
}

.stage-item__sub {
  font-size: 0.72rem;
  color: var(--text-dim);
}

.stage-winner-badge {
  background: var(--primary);
  color: #fff;
  font-size: 0.68rem;
  font-weight: 700;
  border-radius: 99px;
  padding: 3px 10px;
  display: inline-block;
  margin-top: 8px;
}

.stage-vs {
  font-size: 0.75rem;
  font-weight: 800;
  color: var(--text-dim);
  text-align: center;
  letter-spacing: 0.08em;
}

.stage-final-note {
  background: rgba(108, 99, 255, 0.07);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 10px 16px;
  font-size: 0.82rem;
  color: var(--text-muted);
  text-align: center;
}

.stage-final-note strong {
  color: var(--primary);
}

/* ── Loading spinner ──────────────────────────────────────── */

.spinner {
  display: none;
  width: 36px;
  height: 36px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin: 0 auto;
}

.spinner.active {
  display: block;
}

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

/* ═══════════════════════════════════════════════════════════════
   BATCH SECTION
═══════════════════════════════════════════════════════════════ */

.batch {
  background: var(--bg2);
}

.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius-lg);
  padding: 48px 24px;
  text-align: center;
  transition: all var(--transition);
  cursor: pointer;
  margin-bottom: 24px;
  background: var(--surface);
}

.upload-zone:hover,
.upload-zone.dragover {
  border-color: var(--primary);
  background: var(--primary-glow);
}

.upload-zone__icon {
  font-size: 3rem;
  margin-bottom: 12px;
}

.upload-zone h3 {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

.upload-zone p {
  font-size: 0.88rem;
}

#batch-file-input {
  display: none;
}

/* Batch Results Table */
.batch-table-wrap {
  overflow-x: auto;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-soft);
}

.batch-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.batch-table th {
  background: var(--surface);
  padding: 14px 16px;
  text-align: left;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
  border-bottom: 1px solid var(--border-soft);
  cursor: pointer;
  user-select: none;
  white-space: nowrap;
}

.batch-table th:hover {
  color: var(--primary);
}

.batch-table th .sort-icon {
  opacity: 0.4;
  margin-left: 4px;
}

.batch-table th.sorted .sort-icon {
  opacity: 1;
  color: var(--primary);
}

.batch-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-soft);
  color: var(--text-muted);
  vertical-align: top;
  max-width: 320px;
}

.batch-table tr:hover td {
  background: var(--card-hover);
}

.score-chip {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 99px;
  font-weight: 700;
  font-size: 0.82rem;
  font-family: "JetBrains Mono", monospace;
  white-space: nowrap;
}

.score-chip--high {
  background: rgba(74, 222, 128, 0.15);
  color: var(--score-good);
}

.score-chip--mid {
  background: rgba(251, 191, 36, 0.15);
  color: var(--score-mid);
}

.score-chip--low {
  background: rgba(248, 113, 113, 0.15);
  color: var(--score-low);
}

.mini-bar {
  display: block;
  height: 4px;
  background: var(--bg2);
  border-radius: 2px;
  margin-top: 6px;
  overflow: hidden;
}

.mini-bar__fill {
  height: 100%;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--primary), var(--accent2));
}

/* CSV format hint */
.csv-hint {
  background: var(--card);
  border-left: 3px solid var(--primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: 14px 20px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.csv-hint code {
  display: inline-block;
  padding: 2px 8px;
  color: var(--accent2);
  background: var(--bg2);
  border-radius: 4px;
  margin: 0 2px;
}

/* ═══════════════════════════════════════════════════════════════
   FEATURES SECTION
═══════════════════════════════════════════════════════════════ */

.feature-card__icon {
  width: 52px;
  height: 52px;
  background: linear-gradient(135deg,
      var(--primary-glow),
      rgba(0, 212, 255, 0.1));
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 18px;
}

.feature-card h3 {
  font-size: 1.05rem;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 0.88rem;
}

/* ═══════════════════════════════════════════════════════════════
   ABOUT SECTION
═══════════════════════════════════════════════════════════════ */

.about {
  background: var(--bg2);
}

.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.tech-tag {
  padding: 6px 16px;
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: 99px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: all var(--transition);
}

.tech-tag:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-glow);
}

/* ═══════════════════════════════════════════════════════════════
   FOOTER
═══════════════════════════════════════════════════════════════ */

.footer {
  border-top: 1px solid var(--border-soft);
  padding: 36px 0;
  text-align: center;
}

.footer p {
  font-size: 0.88rem;
  color: var(--text-dim);
}

.footer a {
  color: var(--primary);
  text-decoration: none;
}

.footer a:hover {
  text-decoration: underline;
}

/* ═══════════════════════════════════════════════════════════════
   MISC UTILITIES
═══════════════════════════════════════════════════════════════ */

.text-center {
  text-align: center;
}

.text-grad {
  background: linear-gradient(135deg, var(--primary), var(--accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.divider {
  height: 1px;
  background: var(--border-soft);
  margin: 20px 0;
}

.flex-center {
  display: flex;
  align-items: center;
  justify-content: center;
}

.gap-2 {
  gap: 8px;
}

.gap-3 {
  gap: 12px;
}

.mb-1 {
  margin-bottom: 4px;
}

.mb-2 {
  margin-bottom: 8px;
}

.mb-3 {
  margin-bottom: 16px;
}

.mb-4 {
  margin-bottom: 24px;
}

.mb-5 {
  margin-bottom: 32px;
}

.hidden {
  display: none !important;
}

/* ── Tooltip ─────────────────────────────────────────────────── */
[data-tooltip] {
  position: relative;
  cursor: help;
}

[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 6px 12px;
  font-size: 0.78rem;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s;
  z-index: 200;
  color: var(--text);
  box-shadow: var(--shadow-sm);
}

[data-tooltip]:hover::after {
  opacity: 1;
}

/* ── Notification toast ────────────────────────────────────── */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px 20px;
  box-shadow: var(--shadow-lg);
  z-index: 9999;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 10px;
  transform: translateY(120%);
  transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  max-width: 320px;
}

.toast.show {
  transform: translateY(0);
}

.toast--success {
  border-left: 3px solid var(--success);
}

.toast--error {
  border-left: 3px solid var(--danger);
}

/* ── Smooth appear on scroll ───────────────────────────────── */
.appear {
  opacity: 0;
  transform: translateY(24px);
  transition:
    opacity 0.6s ease,
    transform 0.6s ease;
}

.appear.in-view {
  opacity: 1;
  transform: translateY(0);
}

/* ═══════════════════════════════════════════════════════════════
   NEW COMPONENTS (ExASAG, METRICS, EQUATIONS)
═══════════════════════════════════════════════════════════════ */

/* Cluster Visualisation */
.cluster-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}

.cluster-header h3 {
  font-size: 1.15rem;
  margin: 0;
}

.cluster-subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.5;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--border-soft);
  padding-bottom: 16px;
}

/* ExASAG Sentence Attribution */
.exasag-info {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 16px;
  line-height: 1.5;
}

.exasag-sentences {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.exasag-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  background: var(--bg2);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  gap: 24px;
  transition: border-color var(--transition);
}

.exasag-row:hover {
  border-color: var(--border);
}

.exasag-text {
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.5;
  flex: 1;
}

.exasag-metrics {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 140px;
}

.exasag-score {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.9rem;
  font-weight: 700;
}

.exasag-bar-track {
  flex: 1;
  height: 6px;
  background: var(--surface);
  border-radius: 3px;
  overflow: hidden;
  position: relative;
}

.exasag-bar {
  height: 100%;
  border-radius: 3px;
  position: absolute;
  top: 0;
  left: 0;
  transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.exasag-bar--pos {
  background: var(--success);
}

.exasag-bar--neg {
  background: var(--danger);
}

/* Metrics Grid */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 32px;
}

.metric-card {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 20px;
  text-align: center;
  transition: all var(--transition);
}

.metric-card:hover {
  border-color: var(--border);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.metric-card__symbol {
  font-size: 1.6rem;
  font-weight: 800;
  font-family: "JetBrains Mono", monospace;
  margin-bottom: 4px;
  color: var(--text);
}

.metric-card__weight {
  font-size: 1.1rem;
  font-weight: 800;
  margin-bottom: 12px;
}

.metric-card__name {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 6px;
}

.metric-card__desc {
  font-size: 0.75rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Equation Box */
.equation-box {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-left: 4px solid var(--primary);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.equation-box__title {
  padding: 12px 20px;
  background: rgba(108, 99, 255, 0.08);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--primary);
  border-bottom: 1px solid var(--border-soft);
}

.equation-box__body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.eq-row {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.eq-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 600;
}

.eq-row code {
  font-size: 0.95rem;
  padding: 8px 12px;
  color: var(--text);
  border: 1px solid var(--border-soft);
  background: var(--bg2);
}

/* Reference List */
.ref-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.ref-item {
  display: flex;
  gap: 12px;
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.ref-num {
  width: 24px;
  height: 24px;
  flex-shrink: 0;
  background: rgba(108, 99, 255, 0.15);
  color: var(--primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.75rem;
}

.ref-item strong {
  color: var(--text);
}

.tbl-th {
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border-soft);
  color: var(--text-dim);
  font-weight: 700;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.tbl-td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border-soft);
}

/* ═══════════════════════════════════════════════════════════════
   HOW TO USE SECTION
═══════════════════════════════════════════════════════════════ */

.how-to-steps {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 24px;
}

.how-to-step {
  display: flex;
  gap: 16px;
  align-items: flex-start;
}

.how-to-step__num {
  min-width: 32px;
  height: 32px;
  background: linear-gradient(135deg, var(--primary), var(--accent2));
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 0.85rem;
  flex-shrink: 0;
  margin-top: 2px;
  box-shadow: 0 2px 8px var(--primary-glow);
}

.how-to-step pre {
  background: var(--bg);
  border: 1px solid var(--border-soft);
  color: var(--text);
  padding: 10px 14px;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.8rem;
  border-radius: var(--radius-sm);
  overflow-x: auto;
  white-space: pre;
}

.how-to-note {
  background: rgba(108, 99, 255, 0.06);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  font-size: 0.87rem;
  line-height: 1.6;
  color: var(--text-muted);
}

/* ═══════════════════════════════════════════════════════════════
   CHAT INTERFACE
═══════════════════════════════════════════════════════════════ */

.chat-section {
  padding: 80px 0;
}

.chat-container {
  max-width: 900px;
  margin: 0 auto;
}

.chat-box {
  background: var(--card);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  min-height: 500px;
  display: flex;
  flex-direction: column;
  margin-bottom: 28px;
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  background: var(--bg2);
}

.chat-messages::-webkit-scrollbar {
  width: 6px;
}

.chat-messages::-webkit-scrollbar-track {
  background: var(--surface);
}

.chat-messages::-webkit-scrollbar-thumb {
  background: var(--primary);
  border-radius: 99px;
}

.chat-message {
  display: flex;
  gap: 12px;
  animation: slideUp 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.chat-message--user {
  justify-content: flex-end;
}

.chat-message--user .chat-message__content {
  background: linear-gradient(135deg, var(--primary), var(--primary-hover));
  color: #fff;
  border-radius: 0 var(--radius-md) var(--radius-sm) var(--radius-md);
  max-width: 70%;
}

.chat-message--assistant .chat-message__content {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md) 0 var(--radius-md) var(--radius-sm);
  max-width: 85%;
  color: var(--text);
}

.chat-message__content {
  padding: 14px 18px;
  font-size: 0.95rem;
  line-height: 1.6;
  word-wrap: break-word;
}

.chat-message__content strong {
  color: inherit;
  font-weight: 700;
}

.chat-message--user .chat-message__content strong {
  color: rgba(255, 255, 255, 0.95);
}

.chat-message__content a {
  color: inherit;
  text-decoration: underline;
  opacity: 0.9;
}

.chat-input-area {
  border-top: 1px solid var(--border-soft);
  padding: 16px 20px;
  background: var(--card);
  display: flex;
  gap: 12px;
  min-height: 80px;
}

.chat-input {
  flex: 1;
  background: var(--bg2);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 12px 14px;
  color: var(--text);
  font-family: inherit;
  font-size: 0.95rem;
  resize: none;
  transition: border-color var(--transition);
}

.chat-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.chat-button {
  align-self: flex-end;
  height: max-content;
  white-space: nowrap;
  padding: 10px 20px;
  font-size: 0.9rem;
}

.chat-button:hover {
  transform: translateY(-2px);
  box-shadow: var(--glow);
}

/* Chat Suggestions */
.chat-suggestions {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 20px;
}

.suggestions-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
}

.suggestion-chip {
  padding: 10px 14px;
  background: var(--bg2);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  font-size: 0.8rem;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition);
  line-height: 1.4;
}

.suggestion-chip:hover {
  background: var(--primary-glow);
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--primary-glow);
}

/* Student Card & Display */
.student-card {
  background: var(--bg2);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-md);
  padding: 16px;
  margin: 8px 0;
}

.student-header {
  margin-bottom: 12px;
}

.student-header h4 {
  font-size: 0.95rem;
  margin: 0 0 4px;
  color: var(--text);
}

.student-header .email {
  font-size: 0.8rem;
  color: var(--text-dim);
  font-family: "JetBrains Mono", monospace;
}

.score-breakdown {
  margin-bottom: 12px;
}

.score-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 8px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-soft);
}

.score-item strong {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
  font-weight: 700;
}

.score-item .score-value {
  font-family: "JetBrains Mono", monospace;
  font-weight: 800;
  font-size: 1.1rem;
}

.score-item .percentage {
  font-size: 0.75rem;
  color: var(--text-dim);
  font-weight: 600;
}

.score-item .score-value.score-high {
  color: var(--success);
}

.score-item .score-value.score-mid {
  color: var(--warning);
}

.score-item .score-value.score-low {
  color: var(--danger);
}

.metrics {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.metric {
  display: flex;
  justify-content: space-between;
  font-size: 0.8rem;
}

.metric strong {
  color: var(--text);
  font-weight: 600;
}

.metric span {
  font-family: "JetBrains Mono", monospace;
  color: var(--primary);
  font-weight: 700;
}

.score-interpretation {
  background: rgba(108, 99, 255, 0.06);
  border-left: 3px solid var(--primary);
  padding: 10px 12px;
  border-radius: 0 4px 4px 0;
  font-size: 0.8rem;
  line-height: 1.4;
}

.score-interpretation strong {
  color: var(--text);
}

/* Student List */
.student-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  background: var(--bg2);
  border-radius: var(--radius-sm);
  margin: 6px 0;
  font-size: 0.85rem;
}

.student-row .rank {
  color: var(--text-dim);
  font-weight: 700;
  min-width: 24px;
}

.student-row .name {
  flex: 1;
  color: var(--text);
  font-weight: 600;
}

.student-row .email {
  color: var(--text-dim);
  font-size: 0.75rem;
  font-family: "JetBrains Mono", monospace;
  flex: 1;
}

.student-row .score-badge {
  padding: 4px 10px;
  border-radius: 99px;
  font-family: "JetBrains Mono", monospace;
  font-weight: 700;
  font-size: 0.82rem;
  min-width: 60px;
  text-align: center;
}

.student-row .score-badge.score-high {
  background: rgba(74, 222, 128, 0.15);
  color: var(--success);
}

.student-row .score-badge.score-mid {
  background: rgba(251, 191, 36, 0.15);
  color: var(--warning);
}

.student-row .score-badge.score-low {
  background: rgba(248, 113, 113, 0.15);
  color: var(--danger);
}

/* Responsive */
@media (max-width: 768px) {
  .demo__layout {
    grid-template-columns: 1fr;
  }

  .chat-messages {
    max-height: 400px;
  }

  .chat-message--user .chat-message__content {
    max-width: 85%;
  }

  .chat-message--assistant .chat-message__content {
    max-width: 95%;
  }

  .suggestions-grid {
    grid-template-columns: 1fr;
  }

  .student-row {
    flex-wrap: wrap;
  }

  .student-row .email {
    flex: 0 0 100%;
  }
}