/* ============================================================
   MarginEasy — shared styles
   Engineered-instrument identity: IBM Plex Sans + Mono, ink
   palette, green/red for direction, amber for the danger number.
   ============================================================ */

:root {
  --font-ui: 'IBM Plex Sans', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, monospace;

  --r: 14px;
  --r-sm: 10px;
  --pad: clamp(18px, 3vw, 30px);
  --gap: 18px;
  --maxw: 1080px;

  --long: #21c08a;
  --short: #f26d78;
  --safe: #21c08a;
  --warn: #f0a93b;
  --crit: #f2545b;
}

:root[data-theme='dark'] {
  --bg: #0e1116;
  --bg-glow: #12161d;
  --surface: #161b23;
  --surface-2: #1c222c;
  --border: #262d38;
  --border-strong: #333c49;
  --text: #e7ebf2;
  --muted: #8a93a3;
  --shadow: 0 24px 60px -30px rgba(0, 0, 0, 0.7);
  --nav-bg: rgba(14, 17, 22, 0.82);
}
:root[data-theme='light'] {
  --bg: #eef1f6;
  --bg-glow: #f6f8fb;
  --surface: #ffffff;
  --surface-2: #f4f6fa;
  --border: #e3e7ee;
  --border-strong: #d3d9e3;
  --text: #171a20;
  --muted: #5a6472;
  --long: #12a575;
  --short: #e0455a;
  --safe: #12a575;
  --warn: #cf8210;
  --crit: #d83a44;
  --shadow: 0 20px 50px -32px rgba(23, 30, 45, 0.4);
  --nav-bg: rgba(255, 255, 255, 0.82);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-ui);
  color: var(--text);
  background:
    radial-gradient(1100px 620px at 82% -10%, var(--bg-glow), transparent 60%),
    var(--bg);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
body[data-dir='long'] { --dir-accent: var(--long); }
body[data-dir='short'] { --dir-accent: var(--short); }
:root { --dir-accent: var(--long); }

a { color: inherit; }
.wrap { width: min(var(--maxw), 100%); margin: 0 auto; padding: 0 clamp(16px, 4vw, 28px); }

/* ---- nav ---- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--nav-bg);
  backdrop-filter: saturate(140%) blur(12px);
  -webkit-backdrop-filter: saturate(140%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  width: min(var(--maxw), 100%);
  margin: 0 auto;
  padding: 12px clamp(16px, 4vw, 28px);
  display: flex;
  align-items: center;
  gap: 16px;
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 700; letter-spacing: -0.02em; font-size: 1.06rem; }
.brand-mark {
  width: 15px; height: 15px; border-radius: 4px;
  background: var(--long);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--long) 18%, transparent);
}
.brand em { font-style: normal; color: var(--muted); font-weight: 500; }
.nav-spacer { flex: 1; }
#navMenu { display: flex; align-items: center; gap: 4px; }
#navMenu a {
  text-decoration: none;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 7px 11px;
  border-radius: 8px;
  white-space: nowrap;
  transition: color .15s, background .15s;
}
#navMenu a:hover { color: var(--text); background: var(--surface-2); }
#navMenu a[aria-current='page'] { color: var(--text); background: var(--surface-2); }
.theme-btn {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 6px 14px;
  cursor: pointer;
  transition: color .15s, border-color .15s;
}
.theme-btn:hover { color: var(--text); border-color: var(--border-strong); }
.nav-toggle {
  display: none;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 10px;
  cursor: pointer;
  color: var(--text);
}

@media (max-width: 860px) {
  .nav-toggle { display: inline-flex; }
  #navMenu {
    display: none;
    position: absolute;
    top: 100%; left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: 10px clamp(16px, 4vw, 28px) 16px;
    background: var(--nav-bg);
    backdrop-filter: saturate(140%) blur(12px);
    -webkit-backdrop-filter: saturate(140%) blur(12px);
    border-bottom: 1px solid var(--border);
  }
  #navMenu.open { display: flex; }
  #navMenu a { padding: 11px 12px; }
}

/* ---- generic section rhythm ---- */
.section { padding: clamp(40px, 7vw, 78px) 0; }
.section-tight { padding: clamp(28px, 5vw, 46px) 0; }
.eyebrow {
  font-size: 0.74rem; font-weight: 600; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--muted); margin: 0 0 12px;
}

/* ---- home hero ---- */
.hero-home { text-align: center; padding: clamp(52px, 8vw, 104px) 0 clamp(30px, 5vw, 54px); }
.hero-home h1 {
  font-size: clamp(2.3rem, 6vw, 3.9rem);
  line-height: 1.02;
  letter-spacing: -0.035em;
  margin: 0 auto 18px;
  max-width: 900px;
  font-weight: 700;
}
.hero-home h1 .accent { color: var(--warn); }
.hero-lead {
  font-size: clamp(1.05rem, 2.4vw, 1.28rem);
  color: var(--muted);
  max-width: 620px;
  margin: 0 auto 30px;
}
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-weight: 600; font-size: 0.96rem;
  padding: 12px 20px; border-radius: var(--r-sm);
  text-decoration: none; cursor: pointer; border: 1px solid transparent;
  transition: transform .12s, background .15s, border-color .15s;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--text); color: var(--bg); }
.btn-primary:hover { background: color-mix(in srgb, var(--text) 88%, var(--warn)); }
.btn-ghost { background: var(--surface); color: var(--text); border-color: var(--border-strong); }
.btn-ghost:hover { border-color: var(--warn); }

/* ---- tool grid ---- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 16px;
}
.tool-card {
  display: block;
  text-decoration: none;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 22px;
  transition: transform .14s, border-color .15s, box-shadow .15s;
}
.tool-card:hover { transform: translateY(-3px); border-color: var(--border-strong); box-shadow: var(--shadow); }
.tool-card .tc-num { font-family: var(--font-mono); font-size: 0.78rem; color: var(--dir-accent, var(--warn)); }
.tool-card h3 { margin: 10px 0 7px; font-size: 1.12rem; letter-spacing: -0.01em; }
.tool-card p { margin: 0; color: var(--muted); font-size: 0.9rem; }
.tool-card .tc-go { margin-top: 14px; font-size: 0.85rem; font-weight: 600; color: var(--text); }
.tool-card:nth-child(1) .tc-num { color: var(--warn); }
.tool-card:nth-child(2) .tc-num { color: var(--long); }
.tool-card:nth-child(3) .tc-num { color: #4cc9f0; }
.tool-card:nth-child(4) .tc-num { color: var(--short); }

/* ---- page header (calculator + content pages) ---- */
.page-head { text-align: center; padding: clamp(34px, 5vw, 58px) 0 clamp(16px, 2vw, 24px); }
.page-head h1 { font-size: clamp(1.9rem, 4.5vw, 2.7rem); letter-spacing: -0.03em; margin: 0 auto 12px; max-width: 22ch; }
.page-head p { color: var(--muted); max-width: 620px; margin: 0 auto; font-size: 1.02rem; }

/* ============================================================
   Calculator card
   ============================================================ */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  box-shadow: var(--shadow);
  overflow: hidden;
}
.mode { display: grid; grid-template-columns: 1fr 1fr; }
.panel { padding: var(--pad); }
.panel-inputs { border-right: 1px solid var(--border); }
.panel-results { display: flex; flex-direction: column; }
.panel-title {
  margin: 0 0 18px; font-size: 0.74rem; font-weight: 600;
  letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted);
}

.dir-toggle {
  display: grid; grid-template-columns: 1fr 1fr; gap: 6px; padding: 5px;
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--r-sm); margin-bottom: var(--gap);
}
.dir-btn {
  font-family: var(--font-ui); font-size: 0.95rem; font-weight: 600;
  padding: 10px; border: 1px solid transparent; border-radius: 7px;
  background: transparent; color: var(--muted); cursor: pointer; transition: all .16s;
}
.dir-long[aria-pressed='true'] { color: #fff; background: var(--long); box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--long) 80%, transparent); }
.dir-short[aria-pressed='true'] { color: #fff; background: var(--short); box-shadow: 0 6px 16px -8px color-mix(in srgb, var(--short) 80%, transparent); }

.field { margin-bottom: var(--gap); }
.field label { display: block; font-size: 0.88rem; font-weight: 500; margin-bottom: 7px; }
.field .hint { font-weight: 400; color: var(--muted); font-size: 0.8rem; }
.field .note {
  margin: 7px 2px 0; font-size: 0.78rem; color: var(--muted); line-height: 1.5;
}
.field .note a { color: var(--dir-accent, var(--warn)); text-decoration: none; border-bottom: 1px dotted currentColor; }
.input-line {
  display: flex; align-items: center;
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--r-sm); padding: 0 12px;
  transition: border-color .15s, box-shadow .15s;
}
.input-line:focus-within {
  border-color: var(--dir-accent, var(--warn));
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--dir-accent, var(--warn)) 16%, transparent);
}
.input-line .prefix, .input-line .suffix { font-family: var(--font-mono); color: var(--muted); font-size: 0.95rem; flex: none; }
.input-line .prefix { margin-right: 4px; }
.input-line .suffix { margin-left: 4px; }
.input-line input {
  flex: 1; width: 100%; border: none; background: transparent; color: var(--text);
  font-family: var(--font-mono); font-size: 1.02rem; padding: 12px 0; outline: none; min-width: 0;
}
.input-line input::placeholder { color: color-mix(in srgb, var(--muted) 70%, transparent); }
input[type='number']::-webkit-outer-spin-button,
input[type='number']::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
input[type='number'] { -moz-appearance: textfield; }
.field:has(input[aria-invalid='true']) .input-line { border-color: var(--crit); }
.err { min-height: 1em; margin: 6px 2px 0; font-size: 0.78rem; color: var(--crit); }

/* results */
.hero { margin-bottom: 20px; }
.hero-price {
  display: flex; align-items: baseline; gap: 4px;
  font-family: var(--font-mono); font-weight: 600; line-height: 1;
  letter-spacing: -0.02em; color: var(--warn);
  font-size: clamp(2.3rem, 7vw, 3.3rem);
}
.hero-cur { font-size: 0.5em; color: color-mix(in srgb, var(--warn) 72%, var(--muted)); }
.hero-price.hero-neutral { color: var(--text); }
.hero-unit { margin-top: 9px; font-size: 0.78rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); }

.gauge { margin-bottom: 22px; }
.gauge-track { height: 12px; border-radius: 999px; background: var(--surface-2); border: 1px solid var(--border); overflow: hidden; }
.gauge-fill { height: 100%; width: 0%; border-radius: 999px; background: var(--safe); transition: width .45s cubic-bezier(.2,.7,.2,1), background .3s; }
.gauge-fill[data-tone='safe'] { background: var(--safe); }
.gauge-fill[data-tone='warn'] { background: var(--warn); }
.gauge-fill[data-tone='crit'] { background: var(--crit); }
.gauge-caption { margin: 10px 2px 0; font-size: 0.82rem; color: var(--muted); }

.stats {
  margin: 0 0 20px; display: grid; gap: 1px;
  background: var(--border); border: 1px solid var(--border);
  border-radius: var(--r-sm); overflow: hidden;
}
.stat { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 12px 14px; background: var(--surface); margin: 0; }
.stat[hidden] { display: none; }
.stat dt { color: var(--muted); font-size: 0.86rem; }
.stat dd { margin: 0; font-family: var(--font-mono); font-size: 0.98rem; font-weight: 500; text-align: right; }
.stat dd[data-sign='pos'] { color: var(--long); }
.stat dd[data-sign='neg'] { color: var(--short); }

.copy-btn {
  margin-top: auto; font-family: var(--font-ui); font-size: 0.92rem; font-weight: 600;
  color: var(--text); background: var(--surface-2); border: 1px solid var(--border-strong);
  border-radius: var(--r-sm); padding: 13px; cursor: pointer; transition: all .15s;
}
.copy-btn:hover { border-color: var(--dir-accent, var(--warn)); }
.copy-btn:active { transform: translateY(1px); }

/* ---- prose content (SEO sections) ---- */
.prose { max-width: 720px; margin-left: auto; margin-right: auto; }
.prose h2 { font-size: clamp(1.4rem, 3vw, 1.9rem); letter-spacing: -0.02em; margin: 40px 0 12px; }
.prose h3 { font-size: 1.12rem; margin: 26px 0 8px; }
.prose p, .prose li { color: var(--text); font-size: 1.0rem; }
.prose p { margin: 0 0 14px; }
.prose ul { padding-left: 20px; margin: 0 0 16px; }
.prose li { margin: 6px 0; }
.prose code {
  font-family: var(--font-mono); font-size: 0.86em; color: var(--text);
  background: var(--surface-2); border: 1px solid var(--border); padding: 1px 6px; border-radius: 5px;
}
.prose a { color: var(--warn); text-decoration: none; border-bottom: 1px solid color-mix(in srgb, var(--warn) 40%, transparent); }
.callout {
  background: var(--surface); border: 1px solid var(--border);
  border-left: 3px solid var(--warn); border-radius: var(--r-sm);
  padding: 16px 18px; margin: 18px 0; color: var(--muted); font-size: 0.94rem;
}

/* ---- FAQ ---- */
.faq { max-width: 720px; margin-left: auto; margin-right: auto; }
.faq details { border-bottom: 1px solid var(--border); }
.faq summary {
  cursor: pointer; list-style: none; padding: 18px 0; font-weight: 600; font-size: 1.02rem;
  display: flex; justify-content: space-between; gap: 16px; align-items: center;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: '+'; font-family: var(--font-mono); color: var(--muted); font-size: 1.2rem; }
.faq details[open] summary::after { content: '\2212'; }
.faq details p { margin: 0 0 18px; color: var(--muted); max-width: 660px; }

/* ---- glossary ---- */
.glossary { display: grid; gap: 12px; max-width: 760px; margin-left: auto; margin-right: auto; }
.term {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r); padding: 18px 20px;
}
.term h3 { margin: 0 0 6px; font-size: 1.06rem; display: flex; align-items: baseline; gap: 10px; }
.term .also { font-size: 0.78rem; color: var(--muted); font-weight: 400; font-family: var(--font-mono); }
.term p { margin: 0; color: var(--muted); font-size: 0.94rem; }
.term code { font-family: var(--font-mono); font-size: 0.85em; background: var(--surface-2); padding: 1px 5px; border-radius: 4px; color: var(--text); }

/* ---- formula reference (details) ---- */
.formula { margin-top: 18px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--r); }
.formula summary { padding: 15px var(--pad); cursor: pointer; font-weight: 500; font-size: 0.92rem; list-style: none; display: flex; gap: 8px; align-items: center; }
.formula summary::-webkit-details-marker { display: none; }
.formula summary::before { content: '+'; font-family: var(--font-mono); color: var(--muted); font-size: 1.1rem; }
.formula[open] summary::before { content: '\2212'; }
.formula-body { padding: 16px var(--pad) var(--pad); color: var(--muted); font-size: 0.9rem; border-top: 1px solid var(--border); }
.formula-body ul { padding-left: 18px; margin: 12px 0; }
.formula-body li { margin: 7px 0; }
.formula-body code { font-family: var(--font-mono); font-size: 0.85em; color: var(--text); background: var(--surface-2); padding: 2px 6px; border-radius: 5px; }

/* ---- footer ---- */
.site-foot { border-top: 1px solid var(--border); margin-top: clamp(40px, 7vw, 80px); }
.foot-inner {
  width: min(var(--maxw), 100%); margin: 0 auto;
  padding: 30px clamp(16px, 4vw, 28px) 40px;
  display: flex; flex-wrap: wrap; gap: 20px 40px; justify-content: space-between;
}
.foot-brand { max-width: 300px; }
.foot-brand p { color: var(--muted); font-size: 0.86rem; margin: 10px 0 0; }
.foot-cols { display: flex; gap: 44px; flex-wrap: wrap; }
.foot-col h4 { font-size: 0.74rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted); margin: 0 0 10px; }
.foot-col a { display: block; text-decoration: none; color: var(--text); font-size: 0.9rem; padding: 4px 0; opacity: 0.85; }
.foot-col a:hover { opacity: 1; color: var(--warn); }
.foot-legal { width: min(var(--maxw), 100%); margin: 0 auto; padding: 0 clamp(16px, 4vw, 28px) 30px; color: var(--muted); font-size: 0.78rem; }

/* ---- responsive ---- */
@media (max-width: 680px) {
  .mode { grid-template-columns: 1fr; }
  .panel-inputs { border-right: none; border-bottom: 1px solid var(--border); }
}

/* ---- a11y ---- */
:focus-visible { outline: 2px solid var(--dir-accent, var(--warn)); outline-offset: 2px; }
@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto; } }