/* GradeKite — distinctive tool UI (indigo / teal / amber) */
:root {
  --bg: #eef2ff;
  --bg-accent: #ecfeff;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-soft: #e0e7ff;
  --accent: #14b8a6;
  --accent-soft: #ccfbf1;
  --success: #059669;
  --success-soft: #d1fae5;
  --warn: #d97706;
  --warn-soft: #fef3c7;
  --danger: #e11d48;
  --danger-soft: #ffe4e6;
  --radius: 16px;
  --radius-sm: 12px;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.06), 0 8px 24px rgba(79, 70, 229, 0.08);
  --shadow-lg: 0 4px 6px rgba(15, 23, 42, 0.04), 0 20px 40px rgba(79, 70, 229, 0.12);
  --font: "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "Cascadia Code", "SF Mono", Menlo, Consolas, monospace;
  --max: 720px;
  --nav-h: 60px;
  --ring-size: 132px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.55;
  color: var(--text);
  background:
    radial-gradient(1200px 500px at 10% -10%, #c7d2fe 0%, transparent 55%),
    radial-gradient(900px 420px at 100% 0%, #a5f3fc 0%, transparent 50%),
    radial-gradient(700px 400px at 50% 100%, #fde68a22 0%, transparent 45%),
    var(--bg);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; }

.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  background: var(--primary); color: #fff; padding: 0.5rem 1rem;
}
.skip-link:focus { left: 0; }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(226,232,240,0.8);
  height: var(--nav-h);
}
.header-inner {
  max-width: 960px; margin: 0 auto; padding: 0 1rem;
  height: 100%; display: flex; align-items: center; justify-content: space-between; gap: 1rem;
}
.logo {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-weight: 800; font-size: 1.2rem; color: var(--text);
  text-decoration: none; letter-spacing: -0.03em;
}
.logo:hover { text-decoration: none; color: var(--primary); }
.logo-mark {
  width: 28px; height: 28px; border-radius: 8px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  box-shadow: 0 4px 12px rgba(79,70,229,0.35);
  position: relative; flex-shrink: 0;
}
.logo-mark::after {
  content: ""; position: absolute; inset: 7px;
  background: #fff; clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
}
.logo span { color: var(--primary); background: linear-gradient(90deg, var(--primary), var(--accent));
  -webkit-background-clip: text; background-clip: text; color: transparent; }

.nav-toggle {
  display: flex; align-items: center; justify-content: center;
  width: 44px; height: 44px; border: 1px solid var(--border);
  border-radius: 12px; background: var(--surface); cursor: pointer;
}
.nav-toggle svg { width: 20px; height: 20px; }
.site-nav {
  display: none; position: absolute; top: var(--nav-h); left: 0; right: 0;
  background: rgba(255,255,255,0.97); border-bottom: 1px solid var(--border);
  padding: 0.75rem 1rem 1rem; flex-direction: column; gap: 0.25rem;
  box-shadow: var(--shadow);
}
.site-nav.open { display: flex; }
.site-nav a {
  color: var(--text); padding: 0.7rem 0.85rem; border-radius: 10px;
  text-decoration: none; font-size: 0.95rem; font-weight: 550; min-height: 44px;
  display: flex; align-items: center;
}
.site-nav a:hover, .site-nav a.active {
  background: var(--primary-soft); color: var(--primary); text-decoration: none;
}

@media (min-width: 768px) {
  .nav-toggle { display: none; }
  .site-nav {
    display: flex; position: static; flex-direction: row; align-items: center;
    border: none; padding: 0; gap: 0.2rem; background: transparent; box-shadow: none;
  }
  .site-nav a { padding: 0.45rem 0.7rem; font-size: 0.875rem; min-height: 0; }
}

/* Layout */
.main { max-width: var(--max); margin: 0 auto; padding: 1.25rem 1rem 3rem; }
.page-wide { max-width: 960px; }

.page-title {
  margin: 0 0 0.4rem; font-size: 1.75rem; font-weight: 800;
  letter-spacing: -0.035em; line-height: 1.2;
}
.page-desc { margin: 0 0 1.25rem; color: var(--muted); font-size: 1rem; }

/* Cards */
.card {
  background: var(--surface); border: 1px solid rgba(226,232,240,0.9);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 1.25rem; margin-bottom: 1.15rem;
}
.card h2 { margin: 0 0 1rem; font-size: 1.1rem; }
.card h3 { margin: 1.25rem 0 0.5rem; font-size: 1rem; }

/* Forms */
label { display: block; font-size: 0.875rem; font-weight: 600; margin-bottom: 0.35rem; color: var(--text); }
.hint { font-weight: 400; color: var(--muted); font-size: 0.8rem; }
input[type="text"], input[type="number"], input[type="email"], select, textarea {
  width: 100%; padding: 0.7rem 0.85rem; font-size: 1rem; font-family: inherit;
  border: 1.5px solid var(--border); border-radius: 12px; background: var(--surface);
  color: var(--text); transition: border-color 0.15s, box-shadow 0.15s; min-height: 48px;
}
input:focus, select:focus, textarea:focus {
  outline: none; border-color: var(--primary); box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.15);
}
.field { margin-bottom: 0.9rem; }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; }
@media (max-width: 480px) { .field-row { grid-template-columns: 1fr; } }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 0.45rem;
  padding: 0.7rem 1.15rem; font-size: 0.95rem; font-weight: 650; font-family: inherit;
  border-radius: 12px; border: 1.5px solid transparent; cursor: pointer;
  text-decoration: none; transition: background 0.15s, border-color 0.15s, transform 0.12s, box-shadow 0.15s;
  min-height: 48px;
}
.btn:hover { text-decoration: none; }
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: linear-gradient(135deg, var(--primary), #6366f1);
  color: #fff; box-shadow: 0 6px 16px rgba(79, 70, 229, 0.35);
}
.btn-primary:hover { background: linear-gradient(135deg, var(--primary-hover), var(--primary)); color: #fff; }
.btn-secondary { background: var(--surface); color: var(--text); border-color: var(--border); }
.btn-secondary:hover { background: var(--bg); border-color: #cbd5e1; }
.btn-ghost { background: transparent; color: var(--muted); border-color: transparent; }
.btn-ghost:hover { color: var(--danger); background: var(--danger-soft); }
.btn-share {
  background: linear-gradient(135deg, var(--accent), #0d9488);
  color: #fff; box-shadow: 0 6px 16px rgba(20, 184, 166, 0.35);
  font-size: 1rem; padding: 0.8rem 1.35rem;
}
.btn-share:hover { filter: brightness(1.05); color: #fff; }
.btn-sm { padding: 0.4rem 0.7rem; font-size: 0.8rem; min-height: 36px; }
.btn-row { display: flex; flex-wrap: wrap; gap: 0.6rem; margin-top: 1rem; }
.btn-row-share { margin-top: 0.85rem; }

/* ============ Result hero ============ */
.result-box {
  position: relative; overflow: hidden;
  background: linear-gradient(145deg, #ffffff 0%, #f5f3ff 55%, #ecfeff 100%);
  border: 1px solid rgba(199, 210, 254, 0.9);
  border-radius: 20px; box-shadow: var(--shadow-lg);
  padding: 1.35rem 1.25rem 1.25rem; margin-bottom: 1.25rem;
}
.result-box::before {
  content: ""; position: absolute; inset: -40% auto auto 55%; width: 280px; height: 280px;
  background: radial-gradient(circle, rgba(20,184,166,0.18), transparent 70%);
  pointer-events: none;
}
.result-inner {
  position: relative; display: flex; align-items: center; gap: 1.15rem; flex-wrap: wrap;
  justify-content: center; text-align: center;
}
@media (min-width: 480px) {
  .result-inner { flex-wrap: nowrap; text-align: left; justify-content: flex-start; }
}

.grade-ring {
  width: var(--ring-size); height: var(--ring-size); flex-shrink: 0; position: relative;
}
.grade-ring svg { width: 100%; height: 100%; transform: rotate(-90deg); }
.grade-ring .track { fill: none; stroke: #e2e8f0; stroke-width: 10; }
.grade-ring .progress {
  fill: none; stroke: url(#gkRingGrad); stroke-width: 10; stroke-linecap: round;
  stroke-dasharray: 339.292; stroke-dashoffset: 339.292;
  transition: stroke-dashoffset 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}
.grade-ring .ring-center {
  position: absolute; inset: 0; display: flex; flex-direction: column;
  align-items: center; justify-content: center; pointer-events: none;
}
.grade-ring .ring-letter {
  font-size: 1.75rem; font-weight: 800; letter-spacing: -0.03em; line-height: 1;
  color: var(--primary);
}
.grade-ring .ring-pct {
  font-size: 0.72rem; font-weight: 600; color: var(--muted); margin-top: 0.15rem;
}

.result-copy { flex: 1; min-width: 160px; }
.result-label {
  font-size: 0.8rem; font-weight: 650; text-transform: uppercase; letter-spacing: 0.06em;
  color: var(--muted); margin-bottom: 0.2rem;
}
.result-value {
  font-size: clamp(2.4rem, 8vw, 3.25rem); font-weight: 800; letter-spacing: -0.04em;
  line-height: 1.05; color: var(--primary);
  font-variant-numeric: tabular-nums;
}
.result-sub { font-size: 0.95rem; color: var(--muted); margin-top: 0.4rem; line-height: 1.45; }
.result-reading {
  margin-top: 0.65rem; padding: 0.75rem 0.9rem;
  background: rgba(255,255,255,0.7); border-radius: 12px;
  border: 1px solid rgba(199,210,254,0.7);
  font-size: 1rem; font-weight: 550; color: var(--text); line-height: 1.45;
}
.result-reading:empty { display: none; }

.result-box.warn { background: linear-gradient(145deg, #fffbeb, #fff7ed); border-color: #fde68a; }
.result-box.warn .result-value, .result-box.warn .ring-letter { color: var(--warn); }
.result-box.success { background: linear-gradient(145deg, #ecfdf5, #f0fdfa); border-color: #a7f3d0; }
.result-box.success .result-value, .result-box.success .ring-letter { color: var(--success); }
.result-box.danger { background: linear-gradient(145deg, #fff1f2, #ffe4e6); border-color: #fecaca; }
.result-box.danger .result-value, .result-box.danger .ring-letter { color: var(--danger); }

/* Celebrate */
.result-box.celebrate { animation: gkPulse 0.9s ease; }
@keyframes gkPulse {
  0% { transform: scale(1); }
  40% { transform: scale(1.02); box-shadow: 0 0 0 6px rgba(16,185,129,0.25), var(--shadow-lg); }
  100% { transform: scale(1); }
}
.confetti {
  position: absolute; inset: 0; pointer-events: none; overflow: hidden; border-radius: 20px;
}
.confetti i {
  position: absolute; top: -8px; width: 8px; height: 8px; border-radius: 2px;
  animation: gkFall 1.1s ease-out forwards;
  opacity: 0.9;
}
@keyframes gkFall {
  0% { transform: translateY(0) rotate(0deg); opacity: 1; }
  100% { transform: translateY(180px) rotate(240deg); opacity: 0; }
}
@media (prefers-reduced-motion: reduce) {
  .result-box.celebrate { animation: none; }
  .confetti, .confetti i { display: none !important; }
  .grade-ring .progress { transition: none; }
  .result-value { transition: none; }
}

/* Tables / rows */
.item-list { display: flex; flex-direction: column; gap: 0.65rem; }
.item-row {
  display: grid; gap: 0.5rem; align-items: end;
  padding: 0.85rem; background: linear-gradient(180deg, #f8fafc, #f1f5f9);
  border-radius: 14px; border: 1px solid var(--border);
}
.item-row.cols-3 { grid-template-columns: 1fr 1fr 1fr auto; }
.item-row.cols-2 { grid-template-columns: 1fr 1fr auto; }
.item-row.cols-4 { grid-template-columns: 1.2fr 0.8fr 0.8fr 0.8fr auto; }
@media (max-width: 560px) {
  .item-row.cols-3, .item-row.cols-4, .item-row.cols-2 { grid-template-columns: 1fr 1fr; }
  .item-row .btn-remove { grid-column: 1 / -1; justify-self: start; }
}
.item-row .field { margin-bottom: 0; }
.btn-remove {
  color: var(--muted); background: transparent; border: none; cursor: pointer;
  padding: 0.5rem 0.65rem; font-size: 0.85rem; border-radius: 8px; min-height: 44px;
}
.btn-remove:hover { color: var(--danger); background: var(--danger-soft); }

/* Category blocks */
.category-block {
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 1rem; margin-bottom: 1rem; background: var(--surface);
  box-shadow: 0 2px 8px rgba(15,23,42,0.04);
}
.category-header {
  display: flex; flex-wrap: wrap; gap: 0.75rem; align-items: end; margin-bottom: 0.75rem;
}
.category-header .field { flex: 1; min-width: 120px; margin-bottom: 0; }
.category-avg {
  font-size: 0.85rem; color: var(--muted); margin-top: 0.5rem;
  padding-top: 0.5rem; border-top: 1px dashed var(--border);
}

/* Mode toggle */
.mode-toggle {
  display: flex; gap: 0.35rem; margin-bottom: 1.15rem;
  background: rgba(255,255,255,0.7); padding: 0.35rem; border-radius: 14px;
  border: 1px solid var(--border); box-shadow: var(--shadow);
}
.mode-toggle button {
  flex: 1; padding: 0.65rem 0.75rem; border: none; border-radius: 10px;
  background: transparent; font-family: inherit; font-size: 0.875rem; font-weight: 650;
  color: var(--muted); cursor: pointer; min-height: 44px;
}
.mode-toggle button.active {
  background: var(--surface); color: var(--primary);
  box-shadow: 0 2px 8px rgba(79,70,229,0.15);
}

/* FAQ */
.faq details {
  border: 1px solid var(--border); border-radius: 12px; margin-bottom: 0.5rem;
  background: var(--surface); padding: 0.85rem 1rem; box-shadow: 0 1px 3px rgba(15,23,42,0.04);
}
.faq summary { cursor: pointer; font-weight: 650; }
.faq details[open] summary { margin-bottom: 0.5rem; }
.faq p { margin: 0; color: var(--muted); font-size: 0.95rem; }

.how-it-works { margin-top: 2rem; }
.how-it-works ol { padding-left: 1.25rem; color: var(--muted); }
.how-it-works li { margin-bottom: 0.4rem; }

.prose h2 { margin-top: 1.75rem; font-size: 1.25rem; }
.prose h3 { margin-top: 1.25rem; font-size: 1.05rem; }
.prose p, .prose li { color: var(--text); }
.prose ul, .prose ol { padding-left: 1.25rem; }
.prose code {
  font-family: var(--mono); font-size: 0.875em;
  background: var(--bg); padding: 0.1em 0.35em; border-radius: 4px;
}
.prose table { width: 100%; border-collapse: collapse; margin: 1rem 0; font-size: 0.9rem; }
.prose th, .prose td { border: 1px solid var(--border); padding: 0.5rem 0.65rem; text-align: left; }
.prose th { background: var(--bg); font-weight: 600; }

.tool-grid { display: grid; grid-template-columns: 1fr; gap: 0.75rem; margin-bottom: 2rem; }
@media (min-width: 560px) { .tool-grid { grid-template-columns: 1fr 1fr; } }
.tool-card {
  display: block; padding: 1.15rem 1.25rem; background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--radius);
  text-decoration: none; color: var(--text);
  box-shadow: var(--shadow); transition: border-color 0.15s, box-shadow 0.15s, transform 0.12s;
}
.tool-card:hover {
  border-color: #a5b4fc; box-shadow: var(--shadow-lg); transform: translateY(-2px);
  text-decoration: none; color: var(--text);
}
.tool-card h2 { margin: 0 0 0.35rem; font-size: 1.05rem; color: var(--primary); }
.tool-card p { margin: 0; font-size: 0.875rem; color: var(--muted); }

.toast {
  position: fixed; bottom: 1.25rem; left: 50%; transform: translateX(-50%) translateY(120%);
  background: var(--text); color: #fff; padding: 0.7rem 1.2rem; border-radius: 12px;
  font-size: 0.9rem; z-index: 200; transition: transform 0.25s ease;
  max-width: 90vw; text-align: center; box-shadow: var(--shadow-lg);
}
.toast.show { transform: translateX(-50%) translateY(0); }

.site-footer {
  border-top: 1px solid var(--border); background: rgba(255,255,255,0.85);
  backdrop-filter: blur(8px); padding: 2rem 1rem; margin-top: 2rem;
}
.footer-inner { max-width: 960px; margin: 0 auto; }
.footer-nav { display: flex; flex-wrap: wrap; gap: 0.75rem 1.25rem; margin-bottom: 1rem; }
.footer-nav a { color: var(--muted); font-size: 0.875rem; }
.footer-nav a:hover { color: var(--primary); }
.footer-copy { font-size: 0.8rem; color: var(--muted); margin: 0; }

.callout {
  background: var(--primary-soft); border-left: 3px solid var(--primary);
  padding: 0.75rem 1rem; margin: 1rem 0; border-radius: 0 12px 12px 0;
  font-size: 0.9rem; color: var(--muted);
}
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0); border: 0;
}