/* ==========================================================================
   FileClip — design tokens
   Concept: "Filed & Stamped" — cool steel-cabinet paper, an official
   stamp-ink indigo, a folder-tab signature divider and a circular
   stamp badge motif. Serif display (letterhead feel) + clean sans body.
   Distinct from CalcMate, CopyKit, and PixelPress.
   ========================================================================== */

:root {
  --paper: #EEF0F3;
  --paper-card: #FFFFFF;
  --grid-line: rgba(29, 34, 51, 0.05);

  --ink: #1D2233;
  --ink-soft: #5A5F6E;
  --ink-faint: #8B90A0;

  --indigo: #3D4F8A;
  --indigo-dark: #2E3D6B;
  --indigo-tint: #E4E7F2;

  --teal: #2E8074;
  --teal-tint: #E1EEEC;
  --gold: #B8863D;
  --gold-tint: #F2E9D8;

  --border: #DCDFE6;
  --alert: #B23A34;

  --font-display: 'Source Serif 4', Georgia, serif;
  --font-body: 'Public Sans', -apple-system, sans-serif;
  --font-mono: 'Source Code Pro', 'Courier New', monospace;

  --radius: 6px;
  --shadow-card: 0 1px 2px rgba(29,34,51,0.06), 0 1px 12px rgba(29,34,51,0.06);
  --shadow-lift: 0 10px 26px rgba(29,34,51,0.12);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink);
  background:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px),
    var(--paper);
  background-size: 26px 26px, 26px 26px, 100% 100%;
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink);
  line-height: 1.2;
  margin: 0 0 0.5em 0;
  font-weight: 700;
  letter-spacing: -0.005em;
}
h1 { font-size: clamp(1.95rem, 3.9vw, 2.7rem); font-weight: 800; }
h2 { font-size: clamp(1.35rem, 2.5vw, 1.75rem); }
h3 { font-size: 1.1rem; }
p { margin: 0 0 1em 0; color: var(--ink); }
a { color: var(--indigo); text-decoration: none; }
a:hover { text-decoration: underline; }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible {
  outline: 2px solid var(--indigo);
  outline-offset: 2px;
}

.wrap { max-width: 1060px; margin: 0 auto; padding: 0 24px; }
.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--indigo-dark);
  font-weight: 600;
}

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(238,240,243,0.9);
  backdrop-filter: blur(6px);
  position: sticky; top: 0; z-index: 40;
}
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { display: flex; align-items: center; gap: 8px; font-family: var(--font-display); font-weight: 800; font-size: 1.15rem; color: var(--ink); }
.logo .mark { color: var(--indigo); }
.site-nav { display: flex; gap: 26px; font-size: 0.94rem; font-weight: 500; }
.site-nav a { color: var(--ink-soft); }
.site-nav a.active, .site-nav a:hover { color: var(--ink); text-decoration: none; }

/* ---------- Folder-tab signature divider ---------- */
.tabstrip { width: 100%; height: 26px; display: block; color: var(--indigo); margin: 0; }
.ruler-section { margin: 60px 0; }

/* ---------- Stamp badge (decorative, used sparingly) ---------- */
.stamp-badge {
  display: inline-flex; align-items: center; justify-content: center;
  width: 74px; height: 74px; border-radius: 50%;
  border: 2.5px solid var(--indigo); color: var(--indigo);
  font-family: var(--font-mono); font-size: 0.62rem; font-weight: 700;
  letter-spacing: 0.05em; text-transform: uppercase; text-align: center;
  transform: rotate(-8deg); opacity: 0.85;
}

/* ---------- Header / Tool ---------- */
.hero { padding: 48px 0 8px; }
.hero-head { max-width: 640px; margin-bottom: 30px; }
.hero-head h1 { margin-bottom: 14px; }
.hero-head p { color: var(--ink-soft); font-size: 1.05rem; }

.tool-card {
  background: var(--paper-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  overflow: hidden;
}
.tabs { display: flex; border-bottom: 1px solid var(--border); background: #F7F8FA; }
.tab-btn {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.02em;
  font-weight: 600;
  color: var(--ink-soft);
  background: none;
  border: none;
  padding: 16px 20px;
  cursor: pointer;
  border-bottom: 3px solid transparent;
  display: flex; align-items: center; gap: 8px;
}
.tab-btn:hover { color: var(--ink); }
.tab-btn[aria-selected="true"] { color: var(--ink); }
.tab-btn[data-tab="merge"][aria-selected="true"] { border-color: var(--indigo); }
.tab-btn[data-tab="split"][aria-selected="true"] { border-color: var(--teal); }
.tab-btn[data-tab="organize"][aria-selected="true"] { border-color: var(--gold); }
.tab-dot { width: 7px; height: 7px; border-radius: 50%; }
.tab-btn[data-tab="merge"] .tab-dot { background: var(--indigo); }
.tab-btn[data-tab="split"] .tab-dot { background: var(--teal); }
.tab-btn[data-tab="organize"] .tab-dot { background: var(--gold); }

.tab-panel { display: none; padding: 30px; }
.tab-panel.active { display: block; }

.drop-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 30px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.drop-zone:hover, .drop-zone.dragover { border-color: var(--indigo); background: var(--indigo-tint); }
.drop-zone p { margin: 0; color: var(--ink-soft); font-size: 0.94rem; }
.drop-zone .drop-icon { color: var(--indigo); margin-bottom: 8px; }

.file-list { margin-top: 16px; display: flex; flex-direction: column; gap: 8px; }
.file-row {
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
  padding: 10px 14px; background: #F7F8FA; border: 1px solid var(--border); border-radius: 4px;
  font-family: var(--font-mono); font-size: 0.85rem;
}
.file-row .fname { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.file-row .fmeta { color: var(--ink-faint); flex-shrink: 0; }
.file-row button { background: none; border: none; color: var(--ink-faint); cursor: pointer; font-size: 1rem; padding: 0 4px; }
.file-row button:hover { color: var(--alert); }
.move-btns { display: flex; gap: 4px; }
.move-btns button { background: none; border: 1px solid var(--border); border-radius: 3px; cursor: pointer; color: var(--ink-soft); padding: 2px 6px; }

.field { display: flex; flex-direction: column; gap: 6px; margin-bottom: 14px; }
.field label { font-size: 0.8rem; font-weight: 600; color: var(--ink-soft); }
.field input[type="text"], .field input[type="number"], .field select {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #FCFCFB;
  color: var(--ink);
}
.field input:focus, .field select:focus { border-color: var(--indigo); }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.field-hint { font-size: 0.8rem; color: var(--ink-faint); margin-top: -8px; }

.status-box {
  margin-top: 16px; padding: 14px 16px; border-radius: 4px;
  background: var(--indigo-tint); border: 1px solid var(--border);
  font-size: 0.9rem; color: var(--ink-soft);
}
.status-box.ready { color: var(--ink); font-weight: 500; }

/* ---------- Buttons ---------- */
.btn {
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.95rem;
  padding: 11px 22px;
  border-radius: 4px;
  border: 1px solid var(--indigo);
  background: var(--indigo);
  color: #FDFDFE;
  cursor: pointer;
  display: inline-flex; align-items: center; gap: 8px;
}
.btn:hover { background: var(--indigo-dark); border-color: var(--indigo-dark); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--ink-soft); background: transparent; }
.toolbar { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 18px; }

/* ---------- Sections / Article grid ---------- */
.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 24px; flex-wrap: wrap; gap: 8px; }
.section-head h2 { margin-bottom: 0; }
.see-all { font-family: var(--font-mono); font-size: 0.85rem; font-weight: 600; }

.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }

.article-card {
  background: var(--paper-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex; flex-direction: column;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  position: relative;
}
.article-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lift); }
.article-card .thumb { width: 100%; aspect-ratio: 16/9; display: block; background: var(--paper); }
.article-card .thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.card-tab {
  position: absolute; top: 0; left: 20px;
  font-family: var(--font-mono); font-size: 0.66rem; letter-spacing: 0.05em; text-transform: uppercase;
  font-weight: 700; color: #fff;
  padding: 4px 10px 5px;
  border-radius: 0 0 4px 4px;
}
.card-tab.merge { background: var(--indigo); }
.card-tab.split { background: var(--teal); }
.card-tab.organize { background: var(--gold); }
.article-card .body { padding: 18px 20px 20px; display: flex; flex-direction: column; gap: 8px; flex: 1; }
.article-card h3 { font-size: 1.02rem; margin-bottom: 0; font-family: var(--font-body); font-weight: 700; }
.article-card h3 a { color: var(--ink); }
.article-card h3 a:hover { color: var(--indigo); text-decoration: none; }
.article-card p { color: var(--ink-soft); font-size: 0.92rem; margin: 0; flex: 1; }
.read-more { font-family: var(--font-mono); font-size: 0.78rem; font-weight: 600; color: var(--indigo-dark); }

.filter-row { display: flex; gap: 10px; margin-bottom: 28px; flex-wrap: wrap; }
.filter-chip {
  font-family: var(--font-mono); font-size: 0.8rem; font-weight: 600;
  padding: 8px 16px; border-radius: 20px; border: 1px solid var(--border);
  background: var(--paper-card); color: var(--ink-soft); cursor: pointer;
}
.filter-chip.active { background: var(--indigo); color: #fff; border-color: var(--indigo); }

/* ---------- Why / features ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feature .num { font-family: var(--font-mono); color: var(--indigo); font-size: 0.82rem; font-weight: 700; }
.feature h3 { margin: 6px 0 6px; font-size: 1.02rem; font-family: var(--font-body); }
.feature p { color: var(--ink-soft); font-size: 0.93rem; margin: 0; }

/* ---------- Footer ---------- */
.site-footer { border-top: 1px solid var(--border); padding: 40px 0; margin-top: 40px; }
.site-footer .wrap { display: flex; justify-content: space-between; align-items: flex-start; flex-wrap: wrap; gap: 24px; }
.footer-cols { display: flex; gap: 60px; flex-wrap: wrap; }
.footer-col h4 { font-family: var(--font-mono); font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--ink-faint); margin-bottom: 10px; }
.footer-col a { display: block; color: var(--ink-soft); font-size: 0.9rem; margin-bottom: 8px; font-family: var(--font-body); }
.footer-col a:hover { color: var(--ink); }
.footer-note { color: var(--ink-faint); font-size: 0.82rem; margin-top: 26px; font-family: var(--font-body); }

/* ---------- Article page ---------- */
.article-header { padding: 42px 0 0; }
.breadcrumb { font-family: var(--font-mono); font-size: 0.76rem; color: var(--ink-faint); margin-bottom: 18px; }
.breadcrumb a { color: var(--ink-faint); }
.article-header .cat-label { font-family: var(--font-mono); font-size: 0.72rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; padding: 4px 10px; border-radius: 3px; display: inline-block; margin-bottom: 14px; color: #fff; }
.cat-label.merge { background: var(--indigo); }
.cat-label.split { background: var(--teal); }
.cat-label.organize { background: var(--gold); }
.article-header h1 { max-width: 760px; }
.article-meta { color: var(--ink-faint); font-size: 0.85rem; font-family: var(--font-mono); margin-bottom: 24px; }
.article-hero-img { width: 100%; max-width: 900px; border-radius: var(--radius); overflow: hidden; margin: 8px 0 34px; box-shadow: var(--shadow-card); }
.article-hero-img img { width: 100%; display: block; }

.article-body { max-width: 720px; }
.article-body h2 { margin-top: 1.6em; font-size: 1.35rem; }
.article-body p { color: var(--ink); font-size: 1.02rem; }
.article-body ul, .article-body ol { color: var(--ink); padding-left: 1.3em; margin-bottom: 1.2em; }
.article-body li { margin-bottom: 0.4em; }
.article-body strong { color: var(--ink); }
.article-body .formula-box {
  font-family: var(--font-mono);
  background: var(--paper-card);
  border: 1px solid var(--border);
  border-left: 3px solid var(--indigo);
  padding: 14px 18px;
  border-radius: 4px;
  margin: 1.4em 0;
  font-size: 0.92rem;
  overflow-x: auto;
}

.tool-cta {
  margin: 2.2em 0;
  padding: 22px 24px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--paper-card);
  display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap;
}
.tool-cta p { margin: 0; font-weight: 500; }

.faq { margin-top: 2.4em; }
.faq-item { border-top: 1px solid var(--border); padding: 18px 0; }
.faq-item h3 { font-size: 1.02rem; margin-bottom: 8px; }
.faq-item p { color: var(--ink-soft); margin: 0; }

/* ---------- Responsive ---------- */
@media (max-width: 880px) {
  .card-grid { grid-template-columns: repeat(2, 1fr); }
  .feature-grid { grid-template-columns: 1fr; gap: 20px; }
  .field-row { grid-template-columns: 1fr; }
}
@media (max-width: 600px) {
  .card-grid { grid-template-columns: 1fr; }
  .tabs { overflow-x: auto; }
  .tab-btn { padding: 14px 14px; white-space: nowrap; }
  .tab-panel { padding: 22px 18px; }
  .site-footer .wrap { flex-direction: column; }
  .footer-cols { gap: 32px; }
}