:root {
  --bg: #FAFAF9;
  --bg-alt: #F0EEE9;
  --charcoal: #1C1C2E;
  --charcoal-mid: #2E2E44;
  --amber: #F59E0B;
  --amber-dim: #D97706;
  --muted: #6B7280;
  --fg: #1C1C2E;
  --fg-inv: #FAFAF9;
  --border: rgba(28,28,46,0.1);
}

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

body {
  font-family: 'DM Sans', sans-serif;
  background: var(--bg);
  color: var(--fg);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ── Navbar ── */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 48px;
  border-bottom: 1px solid var(--border);
}

.nav-logo {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 22px;
  letter-spacing: -0.5px;
  color: var(--charcoal);
}

.nav-tagline {
  font-size: 13px;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ── Hero ── */
.hero {
  padding: 96px 48px 80px;
  background: var(--charcoal);
  color: var(--fg-inv);
}

.hero-inner {
  max-width: 860px;
}

.hero-eyebrow {
  font-family: 'Syne', sans-serif;
  font-weight: 600;
  font-size: 13px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 20px;
}

.hero-headline {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(40px, 6vw, 76px);
  line-height: 1.05;
  letter-spacing: -2px;
  color: var(--fg-inv);
  margin-bottom: 28px;
}

.hero-sub {
  font-size: 19px;
  color: rgba(250,250,249,0.7);
  max-width: 600px;
  line-height: 1.65;
}

/* ── How ── */
.how {
  padding: 96px 48px;
  background: var(--bg);
}

.how-header {
  max-width: 700px;
  margin-bottom: 72px;
}

.how-header h2 {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: clamp(24px, 3.5vw, 40px);
  line-height: 1.2;
  letter-spacing: -0.5px;
  margin-bottom: 14px;
}

.how-header p {
  font-size: 18px;
  color: var(--muted);
}

.how-steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border: 1px solid var(--border);
}

.step {
  padding: 36px 32px;
  border-right: 1px solid var(--border);
}
.step:last-child { border-right: none; }

.step-num {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--amber);
  margin-bottom: 12px;
}

.step-label {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.3px;
  margin-bottom: 10px;
}

.step-desc {
  font-size: 14px;
  color: var(--muted);
  line-height: 1.6;
}

/* ── Features ── */
.features {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
}

.features-col {
  padding: 72px 48px;
  background: var(--bg-alt);
}

.feature { margin-bottom: 48px; }
.feature:last-child { margin-bottom: 0; }

.feature-icon {
  font-size: 28px;
  color: var(--amber);
  margin-bottom: 14px;
  display: block;
}

.feature h3 {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.3px;
  margin-bottom: 10px;
}

.feature p {
  font-size: 15px;
  color: var(--muted);
  line-height: 1.65;
}

/* ── Numbers ── */
.numbers {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 64px 48px;
  background: var(--charcoal);
  color: var(--fg-inv);
}

.num-item {
  text-align: center;
  flex: 1;
}

.num-val {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(36px, 4vw, 56px);
  letter-spacing: -2px;
  color: var(--amber);
  margin-bottom: 8px;
}

.num-label {
  font-size: 13px;
  color: rgba(250,250,249,0.5);
  letter-spacing: 0.05em;
}

.num-divider {
  width: 1px;
  height: 60px;
  background: rgba(250,250,249,0.15);
}

/* ── Closing ── */
.closing {
  padding: 96px 48px;
  background: var(--bg);
  border-top: 1px solid var(--border);
}

.closing-inner {
  max-width: 760px;
}

.closing-statement {
  font-family: 'Syne', sans-serif;
  font-weight: 600;
  font-size: clamp(20px, 2.5vw, 28px);
  line-height: 1.45;
  letter-spacing: -0.3px;
  margin-bottom: 24px;
}

.closing-sub {
  font-size: 15px;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ── Footer ── */
footer {
  padding: 36px 48px;
  background: var(--charcoal);
  color: rgba(250,250,249,0.4);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-brand {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 18px;
  color: var(--fg-inv);
}

.footer-tagline {
  font-size: 13px;
  letter-spacing: 0.05em;
}

/* ── Nav: right side + CTA button ── */
.nav-right {
  display: flex;
  align-items: center;
  gap: 24px;
}

.btn-nav {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--charcoal);
  background: var(--amber);
  padding: 9px 20px;
  border-radius: 4px;
  text-decoration: none;
  transition: background 0.15s;
}
.btn-nav:hover { background: var(--amber-dim); }

/* ── Hero CTA ── */
.hero-cta {
  display: inline-block;
  margin-top: 36px;
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 15px;
  color: var(--fg-inv);
  background: var(--amber);
  padding: 14px 28px;
  border-radius: 4px;
  text-decoration: none;
  letter-spacing: 0.02em;
  transition: background 0.15s;
}
.hero-cta:hover { background: var(--amber-dim); }

/* ── Grade Page ── */
.grade-page {
  min-height: calc(100vh - 80px);
  padding: 64px 48px;
  max-width: 800px;
  margin: 0 auto;
}

.grade-header {
  text-align: center;
  margin-bottom: 48px;
}

.grade-header h1 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(28px, 4vw, 44px);
  letter-spacing: -1px;
  color: var(--charcoal);
  margin-bottom: 12px;
}

.grade-header p {
  color: var(--muted);
  font-size: 17px;
}

.upload-zone {
  border: 2px dashed var(--border);
  border-radius: 12px;
  padding: 48px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  position: relative;
}
.upload-zone:hover, .upload-zone.drag-over {
  border-color: var(--amber);
  background: rgba(245,158,11,0.04);
}
.upload-zone input[type="file"] {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
}
.upload-icon {
  font-size: 48px;
  color: var(--amber);
  margin-bottom: 16px;
}
.upload-text {
  font-size: 16px;
  color: var(--muted);
}
.upload-text strong { color: var(--charcoal); }

.preview-wrap {
  margin-top: 24px;
  display: none;
}
.preview-wrap.visible { display: block; }
.preview-wrap img {
  max-width: 100%;
  max-height: 320px;
  border-radius: 8px;
  border: 1px solid var(--border);
}

.grade-btn {
  display: block;
  width: 100%;
  margin-top: 24px;
  padding: 16px;
  background: var(--charcoal);
  color: var(--fg-inv);
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 16px;
  letter-spacing: 0.04em;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.15s;
}
.grade-btn:hover { background: var(--charcoal-mid); }
.grade-btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* Result card */
.result-card {
  margin-top: 48px;
  background: var(--charcoal);
  color: var(--fg-inv);
  border-radius: 16px;
  padding: 40px;
  display: none;
}
.result-card.visible { display: block; }

.result-grade-label {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 64px;
  letter-spacing: -3px;
  color: var(--amber);
  line-height: 1;
  margin-bottom: 8px;
}

.result-category {
  font-size: 18px;
  color: rgba(250,250,249,0.7);
  margin-bottom: 32px;
}

.result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-bottom: 32px;
}

.result-stat-label {
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(250,250,249,0.4);
  margin-bottom: 6px;
}

.result-stat-val {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 22px;
  color: var(--fg-inv);
}

.result-reasoning {
  font-size: 15px;
  color: rgba(250,250,249,0.65);
  line-height: 1.6;
  border-top: 1px solid rgba(250,250,249,0.1);
  padding-top: 24px;
}

.result-actions {
  margin-top: 32px;
  display: flex;
  gap: 12px;
}

.btn-ghost {
  flex: 1;
  padding: 12px 20px;
  background: transparent;
  border: 1px solid rgba(250,250,249,0.2);
  color: var(--fg-inv);
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.04em;
  border-radius: 6px;
  cursor: pointer;
  text-align: center;
  text-decoration: none;
  transition: border-color 0.15s;
}
.btn-ghost:hover { border-color: rgba(250,250,249,0.5); }

/* Error state */
.error-msg {
  background: #FEF2F2;
  border: 1px solid #FECACA;
  color: #991B1B;
  border-radius: 8px;
  padding: 12px 16px;
  margin-top: 16px;
  font-size: 14px;
  display: none;
}
.error-msg.visible { display: block; }

/* ── Mobile ── */
@media (max-width: 768px) {
  .navbar { padding: 16px 24px; }
  .hero { padding: 64px 24px 56px; }
  .how { padding: 64px 24px; }
  .how-header { margin-bottom: 48px; }
  .how-steps { grid-template-columns: 1fr; gap: 0; }
  .step { border-right: none; border-bottom: 1px solid var(--border); padding: 28px 0; }
  .step:last-child { border-bottom: none; }
  .features { grid-template-columns: 1fr; }
  .features-col { padding: 56px 24px; }
  .numbers { flex-wrap: wrap; gap: 32px; padding: 48px 24px; }
  .num-item { flex: 0 0 calc(50% - 16px); }
  .num-divider { display: none; }
  .closing { padding: 64px 24px; }
  footer { padding: 24px; flex-direction: column; gap: 8px; text-align: center; }
}