:root {
  --ink: #1E293B;
  --ink-soft: #475569;
  --muted: #64748B;
  --accent: #0EA5E9;
  --accent-dark: #0284C7;
  --accent-soft: #E0F2FE;
  --bg: #F8FAFC;
  --card: #FFFFFF;
  --border: #E2E8F0;
  --radius: 14px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}

.container { max-width: 880px; margin: 0 auto; padding: 0 20px; }
.muted { color: var(--muted); }
.small { font-size: 13px; }

/* ---------- header ---------- */
.site-header {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 60px; gap: 12px;
}
.logo {
  font-size: 20px; font-weight: 800; color: var(--ink); text-decoration: none; letter-spacing: -0.02em;
}
.logo span { color: var(--accent); font-weight: 600; }
.logo .dot { color: var(--muted); font-weight: 500; font-size: 15px; }
.badge-free {
  font-size: 12px; font-weight: 600; color: var(--accent-dark);
  background: var(--accent-soft); border: 1px solid #BAE6FD;
  padding: 5px 12px; border-radius: 999px; white-space: nowrap;
}

/* ---------- hero / tool ---------- */
.hero { padding: 48px 0 8px; text-align: center; }
h1 { font-size: clamp(30px, 5vw, 42px); letter-spacing: -0.03em; line-height: 1.15; }
.subtitle { max-width: 620px; margin: 14px auto 30px; color: var(--ink-soft); font-size: 17px; }

.dropzone {
  background: var(--card);
  border: 2px dashed #B6C5D8;
  border-radius: var(--radius);
  padding: 46px 24px;
  cursor: pointer;
  transition: border-color .15s, background .15s;
  color: var(--ink-soft);
}
.dropzone:hover, .dropzone:focus-visible { border-color: var(--accent); background: #F0F9FF; outline: none; }
.dropzone.dragging { border-color: var(--accent); background: var(--accent-soft); }
.icon-upload { color: var(--accent); margin-bottom: 10px; }
.dz-title { font-size: 19px; font-weight: 700; color: var(--ink); }
.dz-sub { font-size: 14px; margin-top: 4px; }
.link-like { color: var(--accent-dark); font-weight: 600; text-decoration: underline; }

/* ---------- controls ---------- */
.controls { margin-top: 20px; text-align: left; }
.file-chip {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--card); border: 1px solid var(--border); border-radius: 10px;
  padding: 9px 14px; font-size: 14px; max-width: 100%;
}
.file-chip span:first-of-type { font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; max-width: 320px; }
.chip-x {
  border: none; background: none; font-size: 18px; color: var(--muted); cursor: pointer; line-height: 1;
}
.chip-x:hover { color: var(--ink); }
.quality-row {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 14px;
}
.quality-row label { font-size: 14px; font-weight: 600; color: var(--ink-soft); }
.quality-row select {
  font-size: 14px; padding: 9px 12px; border: 1px solid var(--border); border-radius: 10px;
  background: var(--card); color: var(--ink); cursor: pointer;
}

.btn-primary {
  display: inline-block; border: none; cursor: pointer;
  background: var(--accent); color: #fff; font-weight: 700; font-size: 15px;
  padding: 11px 26px; border-radius: 10px; text-decoration: none;
  transition: background .15s;
}
.btn-primary:hover { background: var(--accent-dark); }
.btn-primary:disabled { background: #94A3B8; cursor: not-allowed; }
.btn-ghost {
  border: 1px solid var(--border); background: var(--card); color: var(--ink-soft);
  font-size: 15px; font-weight: 600; padding: 11px 20px; border-radius: 10px; cursor: pointer;
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent-dark); }

/* ---------- progress ---------- */
.progress-wrap { margin-top: 22px; text-align: left; }
.progress-bar {
  height: 10px; background: #E2E8F0; border-radius: 999px; overflow: hidden; margin-top: 8px;
}
.progress-fill { height: 100%; width: 0%; background: var(--accent); border-radius: 999px; transition: width .2s; }

/* ---------- result ---------- */
.result {
  margin-top: 24px; background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; text-align: center;
}
.result-title { font-size: 19px; font-weight: 800; color: #059669; margin-bottom: 4px; }
.result audio { width: 100%; max-width: 480px; margin: 16px 0; }
.result-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

.error {
  margin-top: 18px; color: #B91C1C; background: #FEF2F2; border: 1px solid #FECACA;
  border-radius: 10px; padding: 12px 16px; font-size: 14px; text-align: left;
}

/* ---------- sections ---------- */
.section { padding: 40px 0 4px; }
.section h2 { font-size: 24px; letter-spacing: -0.02em; margin-bottom: 18px; }
.steps { padding-left: 22px; display: grid; gap: 10px; color: var(--ink-soft); }
.steps strong { color: var(--ink); }

.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.feature-card, .guide-card {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px;
}
.feature-card h3, .guide-card h3 { font-size: 15.5px; margin-bottom: 6px; }
.feature-card p, .guide-card p { font-size: 14px; color: var(--ink-soft); }

.guide-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }

.prose p { color: var(--ink-soft); margin-bottom: 12px; max-width: 760px; }

.faq-item {
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  padding: 14px 18px; margin-bottom: 10px;
}
.faq-item summary { font-weight: 600; cursor: pointer; list-style-position: outside; }
.faq-item p { margin-top: 8px; font-size: 14.5px; color: var(--ink-soft); }

/* ---------- footer ---------- */
.site-footer {
  margin-top: 56px; border-top: 1px solid var(--border); background: var(--card);
  padding: 26px 0; text-align: center;
}
.footer-line { font-size: 14px; color: var(--ink-soft); margin-bottom: 6px; }

@media (max-width: 720px) {
  .feature-grid { grid-template-columns: 1fr 1fr; }
  .guide-grid { grid-template-columns: 1fr; }
  .quality-row { flex-direction: column; align-items: stretch; }
  .btn-primary { width: 100%; text-align: center; }
  .badge-free { display: none; }
}
@media (max-width: 460px) {
  .feature-grid { grid-template-columns: 1fr; }
}