:root {
  --ink: #142b3d;
  --muted: #607384;
  --surface: #ffffff;
  --surface-soft: #f4f7f9;
  --surface-accent: #e9f3f7;
  --line: #d8e2e8;
  --line-strong: #b8c9d3;
  --primary: #173b57;
  --primary-strong: #0f2d44;
  --accent: #c66b32;
  --success: #217052;
  --danger: #a33a3a;
  --shadow: 0 18px 55px rgba(25, 58, 79, 0.12);
  --radius-lg: 22px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --page: 1180px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 88% 8%, rgba(198, 107, 50, 0.1), transparent 22rem),
    linear-gradient(180deg, #f8fafb 0, #fff 32rem);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.55;
}

button, input, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: var(--primary); }
img, svg { display: block; }

.page-width {
  width: min(calc(100% - 40px), var(--page));
  margin-inline: auto;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  clip-path: inset(50%);
  left: 0;
  top: 0;
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: fixed;
  z-index: 100;
  left: 16px;
  top: 12px;
  transform: translateY(-150%);
  padding: 10px 14px;
  border-radius: 8px;
  color: #fff;
  background: var(--primary);
}
.skip-link:focus { transform: translateY(0); }

.site-header {
  border-bottom: 1px solid rgba(184, 201, 211, 0.65);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(16px);
}

.header-inner {
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--ink);
  font-size: 0.98rem;
  font-weight: 760;
  text-decoration: none;
}

.github-button,
.primary-button,
.secondary-button,
.text-button,
.mode-tab,
.icon-button {
  border: 0;
  cursor: pointer;
}

.github-button {
  min-height: 42px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0 15px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  color: var(--ink);
  background: #fff;
  font-weight: 700;
  text-decoration: none;
  transition: border-color 160ms ease, transform 160ms ease, box-shadow 160ms ease;
}
.github-button svg { width: 19px; height: 19px; fill: currentColor; }
.github-button:hover { border-color: var(--primary); box-shadow: 0 7px 20px rgba(23, 59, 87, 0.1); transform: translateY(-1px); }

.hero { padding-block: 58px 30px; }
.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 820;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}
.hero h1,
.section-heading h2 {
  margin: 0;
  max-width: 850px;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 650;
  letter-spacing: -0.035em;
  line-height: 1.04;
}
.hero h1 { font-size: clamp(2.35rem, 6vw, 4.75rem); }
.hero-copy {
  max-width: 790px;
  margin: 18px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.18rem);
}

.calculator {
  padding-bottom: 76px;
}

.mode-switcher {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 6px;
  width: min(100%, 650px);
  margin-bottom: 12px;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.8);
}

.mode-tab {
  min-height: 46px;
  padding: 8px 12px;
  border-radius: 11px;
  color: var(--muted);
  background: transparent;
  font-size: 0.91rem;
  font-weight: 760;
}
.mode-tab:hover { color: var(--ink); background: var(--surface-soft); }
.mode-tab.is-active { color: #fff; background: var(--primary); box-shadow: 0 8px 20px rgba(23, 59, 87, 0.18); }

.calculator-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(310px, 0.75fr);
  gap: 18px;
  align-items: start;
}

.calculator-grid > *,
.mode-panel,
.table-scroll {
  min-width: 0;
}

.input-card,
.result-card {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: rgba(255, 255, 255, 0.96);
  box-shadow: var(--shadow);
}

.input-card { min-height: 580px; padding: clamp(20px, 3vw, 32px); }
.result-card { position: sticky; top: 20px; padding: clamp(22px, 3vw, 30px); }

.mode-panel[hidden] { display: none; }
.panel-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 22px;
}
.panel-heading h2,
.result-card h2,
.target-heading h3 { margin: 0; line-height: 1.2; }
.panel-heading h2 { font-size: clamp(1.35rem, 3vw, 1.8rem); }
.panel-heading p,
.target-heading p { margin: 6px 0 0; color: var(--muted); }

.primary-button,
.secondary-button,
.text-button {
  min-height: 44px;
  border-radius: 11px;
  font-weight: 760;
  transition: transform 150ms ease, box-shadow 150ms ease, border-color 150ms ease;
}
.primary-button { padding: 0 17px; color: #fff; background: var(--primary); }
.primary-button:hover:not(:disabled) { background: var(--primary-strong); box-shadow: 0 8px 20px rgba(23, 59, 87, 0.2); transform: translateY(-1px); }
.secondary-button { padding: 0 15px; border: 1px solid var(--line-strong); color: var(--ink); background: #fff; }
.secondary-button:hover:not(:disabled) { border-color: var(--primary); box-shadow: 0 6px 16px rgba(23, 59, 87, 0.08); }
.text-button { padding: 0 8px; color: var(--muted); background: transparent; }
.text-button:hover { color: var(--danger); }
button:disabled { cursor: not-allowed; opacity: 0.48; }

.table-scroll { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius-md); }
.entry-table { width: 100%; min-width: 550px; border-collapse: collapse; }
.entry-table th {
  padding: 11px 12px;
  color: var(--muted);
  background: var(--surface-soft);
  font-size: 0.76rem;
  letter-spacing: 0.045em;
  text-align: left;
  text-transform: uppercase;
}
.entry-table td { padding: 8px 8px 8px 12px; border-top: 1px solid var(--line); }
.entry-table td:nth-child(1) { width: 42%; }
.entry-table td:nth-child(2),
.entry-table td:nth-child(3) { width: 24%; }
.entry-table td:last-child { width: 46px; padding-left: 2px; }

input,
select {
  width: 100%;
  min-height: 44px;
  padding: 9px 11px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  color: var(--ink);
  background: #fff;
  outline: none;
  transition: border-color 150ms ease, box-shadow 150ms ease;
}
input:focus,
select:focus,
button:focus-visible,
a:focus-visible,
summary:focus-visible {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(23, 59, 87, 0.16);
  outline: none;
}
input[aria-invalid="true"] { border-color: var(--danger); box-shadow: 0 0 0 3px rgba(163, 58, 58, 0.1); }

.icon-button {
  width: 40px;
  min-height: 40px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  color: var(--muted);
  background: transparent;
  font-size: 1.25rem;
}
.icon-button:hover { color: var(--danger); background: #fff0f0; }

.target-box {
  margin-top: 18px;
  padding: 18px;
  border: 1px solid #cbdde5;
  border-radius: var(--radius-md);
  background: var(--surface-accent);
}
.target-heading { margin-bottom: 14px; }
.target-heading h3 { font-size: 1rem; }
.target-heading p { font-size: 0.9rem; }
.field-grid { display: grid; gap: 14px; }
.two-columns { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.full-width { grid-column: 1 / -1; }
.field { display: grid; gap: 7px; color: var(--ink); font-size: 0.88rem; font-weight: 710; }
.input-suffix { display: flex; align-items: center; overflow: hidden; border: 1px solid var(--line-strong); border-radius: var(--radius-sm); background: #fff; }
.input-suffix:focus-within { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(23, 59, 87, 0.16); }
.input-suffix input { border: 0; box-shadow: none; }
.input-suffix span { padding-right: 12px; color: var(--muted); font-weight: 700; }
.cgpa-grid { max-width: 640px; }
.custom-formula { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.custom-formula[hidden] { display: none; }
.formula-preview { margin-top: 18px; padding: 13px 15px; border-radius: 11px; color: var(--primary); background: var(--surface-accent); font-weight: 700; }
.form-error { min-height: 24px; margin: 16px 0 0; color: var(--danger); font-size: 0.9rem; font-weight: 680; }

.result-topline { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.result-label { color: var(--accent); font-size: 0.76rem; font-weight: 820; letter-spacing: 0.1em; text-transform: uppercase; }
.status-dot { display: inline-flex; align-items: center; gap: 7px; color: var(--muted); font-size: 0.8rem; font-weight: 700; }
.status-dot::before { content: ""; width: 8px; height: 8px; border-radius: 50%; background: var(--line-strong); }
.status-dot.is-valid::before { background: var(--success); }
.status-dot.is-error::before { background: var(--danger); }
.result-card h2 { margin-top: 13px; font-size: 1.2rem; }
.percentage-output { display: flex; align-items: flex-end; gap: 5px; margin: 10px 0 18px; font-family: Georgia, "Times New Roman", serif; color: var(--primary); line-height: 0.95; }
.percentage-output span:first-child { font-size: clamp(4rem, 8vw, 6.3rem); letter-spacing: -0.07em; }
.percentage-output span:last-child { padding-bottom: 10px; font-size: 1.8rem; font-weight: 700; }

.classification-card,
.target-result {
  display: grid;
  gap: 4px;
  padding: 14px 15px;
  border-radius: 12px;
}
.classification-card { border: 1px solid #d4e4d8; background: #f0f8f3; }
.classification-card span,
.target-result span { color: var(--muted); font-size: 0.76rem; font-weight: 760; letter-spacing: 0.04em; text-transform: uppercase; }
.classification-card strong,
.target-result strong { line-height: 1.35; }
.result-breakdown { margin: 18px 0; }
.result-breakdown div { display: grid; grid-template-columns: 88px 1fr; gap: 14px; padding: 10px 0; border-bottom: 1px solid var(--line); }
.result-breakdown dt { color: var(--muted); font-size: 0.83rem; }
.result-breakdown dd { margin: 0; overflow-wrap: anywhere; font-size: 0.88rem; font-weight: 650; text-align: right; }
.target-result { min-height: 72px; background: var(--surface-soft); }
.target-result.is-success { color: #174d3a; background: #edf8f2; }
.target-result.is-warning { color: #7c431e; background: #fff3e9; }
.result-actions { display: grid; grid-template-columns: 1fr 1fr; gap: 9px; margin-top: 17px; }
.result-actions .text-button { grid-column: 1 / -1; }
.action-feedback { min-height: 21px; margin: 7px 0 0; color: var(--success); font-size: 0.82rem; text-align: center; }
.noscript-message { padding: 14px; border-radius: 10px; color: var(--danger); background: #fff0f0; }

.content-section { padding-block: 66px; border-top: 1px solid var(--line); }
.section-heading { margin-bottom: 28px; }
.section-heading h2 { font-size: clamp(2rem, 5vw, 3.25rem); }
.feature-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; }
.feature-grid article,
.formula-list article {
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface);
}
.feature-grid h3,
.formula-list h3 { margin: 0 0 8px; font-size: 1.05rem; }
.feature-grid p,
.formula-list p { margin: 0; color: var(--muted); font-size: 0.94rem; }
.formula-list { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; }
.formula-list code { display: block; margin: 11px 0; padding: 12px; border-radius: 9px; color: var(--primary); background: var(--surface-accent); white-space: normal; }
.faq-list { display: grid; gap: 10px; }
.faq-list details { border: 1px solid var(--line); border-radius: 12px; background: #fff; }
.faq-list summary { cursor: pointer; padding: 17px 19px; font-weight: 760; }
.faq-list p { margin: 0; padding: 0 19px 18px; color: var(--muted); }
.references ul { display: grid; gap: 10px; padding-left: 20px; }
.references a { text-underline-offset: 3px; }
.site-footer { padding: 27px 0; border-top: 1px solid var(--line); color: var(--muted); background: #fff; font-size: 0.88rem; text-align: center; }

@media (max-width: 900px) {
  .calculator-grid { grid-template-columns: 1fr; }
  .result-card { position: static; }
  .feature-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 650px) {
  .page-width { width: min(calc(100% - 24px), var(--page)); }
  .header-inner { min-height: 62px; }
  .brand span { display: none; }
  .github-button { min-height: 40px; }
  .hero { padding-block: 40px 23px; }
  .mode-switcher { grid-template-columns: 1fr 1fr; }
  .input-card, .result-card { border-radius: 17px; box-shadow: 0 12px 32px rgba(25, 58, 79, 0.1); }
  .input-card { min-height: 0; padding: 18px 14px; }
  .result-card { padding: 22px 18px; }
  .entry-table { min-width: 0; table-layout: fixed; }
  .entry-table th { padding: 8px 4px; font-size: 0.64rem; }
  .entry-table td { padding: 6px 3px; }
  .entry-table td:nth-child(1) { width: 36%; padding-left: 6px; }
  .entry-table td:nth-child(2),
  .entry-table td:nth-child(3) { width: 27%; }
  .entry-table td:last-child { width: 10%; padding: 2px; }
  .entry-table input { min-height: 40px; padding: 7px 6px; font-size: 0.82rem; }
  .icon-button { width: 34px; min-height: 36px; }
  .panel-heading { align-items: stretch; flex-direction: column; gap: 14px; }
  .panel-heading .add-row { align-self: flex-start; }
  .two-columns, .custom-formula { grid-template-columns: 1fr; }
  .feature-grid, .formula-list { grid-template-columns: 1fr; }
  .content-section { padding-block: 52px; }
  .result-actions { grid-template-columns: 1fr; }
  .result-actions .text-button { grid-column: auto; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}

@media print {
  body { background: #fff; }
  .site-header, .hero, .mode-switcher, .input-card, .content-section, .site-footer, .result-actions, .action-feedback { display: none !important; }
  .calculator { padding: 0; }
  .calculator-grid { display: block; }
  .result-card { position: static; border: 0; box-shadow: none; }
}