:root {
  --primary: #7C3AED;
  --primary-soft: #A78BFA;
  --ok: #10b981;
  --warn: #f59e0b;
  --bad: #ef4444;
  --bg: #f8f7ff;
  --card: #ffffff;
  --ink: #1f2430;
  --muted: #5b6172;
  --subtle: #8b90a0;
  --border: #e5e4f0;
  --shadow: 0 10px 40px rgba(60, 40, 120, 0.08);
  --nav-bg: rgba(255, 255, 255, 0.8);
  --wk: 44px;   /* white key width  */
  --bk: 26px;   /* black key width  */
}

[data-theme="dark"] {
  --primary: #A78BFA;
  --primary-soft: #7C3AED;
  --ok: #34d399;
  --bad: #f87171;
  --bg: #14121f;
  --card: #1e1b2e;
  --ink: #ECEAF6;
  --muted: #a9a6c0;
  --subtle: #6f6b85;
  --border: #2c2840;
  --shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
  --nav-bg: rgba(20, 18, 31, 0.82);
}

* { box-sizing: border-box; margin: 0; }
html { -webkit-text-size-adjust: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  transition: background .3s ease, color .3s ease;
}
.wrap { max-width: 820px; margin: 0 auto; padding: 24px 16px 64px; }

/* ===== Top navigation ===== */
.navbar {
  position: sticky; top: 0; z-index: 50;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: 1080px; margin: 0 auto; padding: 0 16px;
  display: flex; align-items: center; gap: 18px; height: 58px;
}
.nav-brand {
  display: flex; align-items: center; gap: 8px;
  font-weight: 800; font-size: 18px; color: var(--ink); text-decoration: none;
  letter-spacing: -.3px; white-space: nowrap;
}
.nav-brand .logo { font-size: 20px; }
.nav-links {
  display: flex; align-items: center; gap: 4px; flex: 1;
}
.nav-group { position: relative; }
.nav-group-btn {
  display: flex; align-items: center; gap: 4px;
  background: transparent; border: 0; color: var(--muted); cursor: pointer;
  font-size: 14px; font-weight: 500; padding: 7px 11px; border-radius: 9px;
  transition: all .15s ease; font-family: inherit;
}
.nav-group-btn svg { transition: transform .2s ease; }
.nav-group-btn:hover { color: var(--ink); background: color-mix(in srgb, var(--primary) 8%, transparent); }
.nav-group.group-active .nav-group-btn { color: var(--primary); }
.nav-dropdown {
  position: absolute; top: calc(100% + 4px); left: 0;
  min-width: 200px; background: var(--card); border: 1px solid var(--border);
  border-radius: 12px; box-shadow: var(--shadow);
  padding: 6px; opacity: 0; visibility: hidden; transform: translateY(-6px);
  transition: all .18s ease; z-index: 60;
}
.nav-group:hover .nav-dropdown,
.nav-group.open .nav-dropdown { opacity: 1; visibility: visible; transform: translateY(0); }
.nav-group:hover .nav-group-btn svg,
.nav-group.open .nav-group-btn svg { transform: rotate(180deg); }
.nav-dropdown a {
  display: block; color: var(--muted); text-decoration: none; font-size: 14px; font-weight: 500;
  padding: 9px 12px; border-radius: 8px; white-space: nowrap; transition: all .12s ease;
}
.nav-dropdown a:hover { color: var(--ink); background: color-mix(in srgb, var(--primary) 10%, transparent); }
.nav-dropdown a.active { color: var(--primary); background: color-mix(in srgb, var(--primary) 12%, transparent); font-weight: 600; }
.nav-right { display: flex; align-items: center; gap: 8px; margin-left: auto; }
#themeBtn {
  background: var(--card); border: 1px solid var(--border); color: var(--ink);
  border-radius: 999px; width: 36px; height: 36px; cursor: pointer; font-size: 15px;
  transition: transform .2s ease, background .3s ease;
}
#themeBtn:hover { transform: scale(1.08); }
.nav-toggle {
  display: none; background: var(--card); border: 1px solid var(--border); color: var(--ink);
  border-radius: 10px; width: 38px; height: 36px; cursor: pointer; font-size: 18px;
}
@media (max-width: 860px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: absolute; top: 58px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--card); border-bottom: 1px solid var(--border);
    padding: 8px 14px 14px; max-height: 0; overflow: hidden;
    transition: max-height .3s ease, padding .3s ease;
    box-shadow: var(--shadow);
  }
  .nav-links.open { max-height: 500px; padding: 8px 14px 14px; overflow-y: auto; }
  .nav-group { width: 100%; }
  .nav-group-btn { width: 100%; justify-content: space-between; padding: 11px 12px; font-size: 15px; }
  .nav-dropdown {
    position: static; opacity: 1; visibility: visible; transform: none;
    box-shadow: none; border: 0; padding: 0 0 4px 12px;
    max-height: 0; overflow: hidden; transition: max-height .25s ease;
  }
  .nav-group.open .nav-dropdown { max-height: 300px; }
  .nav-dropdown a { padding: 10px 12px; font-size: 14px; }
}

.hero { text-align: center; padding: 20px 0 8px; }
h1 { font-size: clamp(28px, 5vw, 44px); letter-spacing: -.5px; line-height: 1.1; }
.subtitle { color: var(--muted); font-size: 18px; margin: 10px 0 18px; }

.tags { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; margin-bottom: 8px; }
.tags span {
  background: var(--card); border: 1px solid var(--border); border-radius: 999px;
  padding: 6px 14px; font-size: 13px; color: var(--ink);
}

/* Tool card */
.tool {
  background: var(--card); border-radius: 20px; box-shadow: var(--shadow);
  padding: 28px; margin-top: 16px; transition: background .3s ease;
}
.settings { display: flex; flex-wrap: wrap; gap: 20px; justify-content: center; margin-bottom: 18px; }
.group { text-align: left; font-size: 13px; }
.group b { display: block; margin-bottom: 8px; color: var(--muted); font-weight: 600; }
.btns { display: flex; flex-wrap: wrap; gap: 6px; }
.btns button {
  border: 1px solid var(--border); background: transparent; color: var(--ink);
  border-radius: 10px; padding: 6px 12px; cursor: pointer; font-size: 13px;
  transition: all .15s ease;
}
.btns button:hover { border-color: var(--primary-soft); }
.btns button.active { background: var(--primary); border-color: var(--primary); color: #fff; }
select {
  padding: 6px 10px; border: 1px solid var(--border); border-radius: 10px;
  background: var(--card); color: var(--ink); font-size: 14px;
}

#startBtn {
  display: block; margin: 10px auto 20px; background: var(--primary); color: #fff;
  border: 0; border-radius: 14px; padding: 14px 40px; font-size: 18px; font-weight: 600;
  cursor: pointer; transition: transform .15s ease, background .2s ease;
}
#startBtn:hover { transform: translateY(-2px); }
#startBtn.recording { background: #ef4444; }

.result { text-align: center; min-height: 130px; }
.note-name { font-size: 72px; font-weight: 800; letter-spacing: -2px; line-height: 1; }
.frequency { color: var(--muted); font-size: 18px; margin-top: 4px; }

.cents-wrap {
  position: relative; height: 36px; border-radius: 999px; margin: 18px 0 8px;
  background: linear-gradient(90deg, var(--warn), #fff 50%, var(--warn));
  overflow: hidden;
}
[data-theme="dark"] .cents-wrap { background: linear-gradient(90deg, var(--warn), #2a2640 50%, var(--warn)); }
.cents-center {
  position: absolute; top: 0; bottom: 0; left: 50%; width: 2px; background: rgba(0,0,0,.12);
  transform: translateX(-50%);
}
#centsMark {
  position: absolute; top: -4px; width: 4px; height: 44px; background: var(--ok);
  left: 50%; border-radius: 2px; transform: translateX(-50%);
  transition: left .08s linear; box-shadow: 0 0 8px var(--ok);
}
.status { min-height: 24px; font-size: 15px; color: var(--muted); font-weight: 600; }
.status.in-tune { color: var(--ok); }
.status.sharp { color: var(--bad); }
.status.flat { color: #3b82f6; }

/* Confidence meter */
.confidence { margin: 14px auto 0; max-width: 360px; }
.confidence .label {
  display: flex; justify-content: space-between; font-size: 12px;
  color: var(--subtle); margin-bottom: 5px; font-weight: 600; letter-spacing: .2px;
}
.conf-track {
  height: 8px; border-radius: 999px; background: var(--border); overflow: hidden;
}
#confBar {
  height: 100%; width: 0%; border-radius: 999px;
  background: linear-gradient(90deg, var(--bad), var(--warn), var(--ok));
  transition: width .12s ease;
}

/* Pitch curve */
.curve-wrap { margin-top: 18px; }
.curve-wrap .cap {
  font-size: 12px; color: var(--subtle); font-weight: 600;
  text-transform: uppercase; letter-spacing: .6px; margin-bottom: 6px;
}
#pitchCurve {
  width: 100%; height: 90px; display: block;
  background: color-mix(in srgb, var(--primary) 5%, transparent);
  border: 1px solid var(--border); border-radius: 12px;
}

/* Piano */
.piano-hint {
  text-align: center; font-size: 12px; font-weight: 700; letter-spacing: 1.5px;
  color: var(--primary-soft); text-transform: uppercase; margin: 18px 0 2px;
}
.piano-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; padding: 8px 0 4px; }
.piano { position: relative; height: calc(var(--wk) * 3.6); margin: 12px auto 0; }
.piano .w {
  position: absolute; top: 0; height: 100%; background: #fff; border: 1px solid #c8c6d6;
  border-radius: 0 0 8px 8px; cursor: pointer; transition: background .08s ease, transform .08s ease;
  display: flex; align-items: flex-end; justify-content: center; padding-bottom: 8px;
}
.piano .w:hover { background: #f1ecff; }
.piano .b {
  position: absolute; top: 0; background: #1d1b2a; border-radius: 0 0 5px 5px;
  cursor: pointer; z-index: 2; transition: background .08s ease, transform .08s ease;
  display: flex; align-items: flex-end; justify-content: center; padding-bottom: 6px;
  box-shadow: 0 4px 6px rgba(0,0,0,.25);
}
.piano .b:hover { background: #3a3650; }
.piano .key-label {
  display: flex; flex-direction: column; align-items: center; line-height: 1.1;
  pointer-events: none; user-select: none;
}
.piano .w .kl-letter { font-size: 11px; color: #b9b5cc; font-weight: 600; }
.piano .w .kl-note { font-size: 12px; color: #4a4560; font-weight: 700; margin-top: 2px; }
.piano .b .key-label { color: #c9c5dd; }
.piano .b .kl-letter { font-size: 10px; color: #8a85a0; font-weight: 600; }
.piano .b .kl-note { font-size: 10px; color: #d8d5e8; font-weight: 700; margin-top: 2px; }
.piano .key-active {
  background: var(--primary) !important;
  box-shadow: 0 0 0 2px color-mix(in srgb, var(--primary) 45%, transparent),
              0 0 18px color-mix(in srgb, var(--primary) 60%, transparent) inset;
  transform: translateY(2px);
}
.piano .key-active .kl-note, .piano .key-active .kl-letter { color: #fff !important; }
.piano .b.key-active { background: var(--primary-soft) !important; }
[data-theme="dark"] .piano .w { background: #f3f1fa; border-color: #15121f; }
[data-theme="dark"] .piano .w .kl-note { color: #2a2640; }

/* Sections */
.steps, .faq, .about, .vote { margin-top: 44px; }
h2 { font-size: 24px; margin-bottom: 14px; letter-spacing: -.3px; }
.steps ol { padding-left: 22px; color: var(--ink); }
.steps li { margin: 8px 0; }
.faq details {
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  padding: 14px 18px; margin: 8px 0; transition: background .3s ease;
}
.faq summary { cursor: pointer; font-weight: 600; }
.faq details p { color: var(--muted); margin-top: 8px; }
.about p { color: var(--muted); margin: 10px 0; }

/* Helpful vote */
.vote { text-align: center; background: var(--card); border: 1px solid var(--border);
  border-radius: 16px; padding: 20px; transition: background .3s ease; }
.vote .q { font-weight: 600; margin-bottom: 10px; }
.vote button {
  border: 1px solid var(--border); background: transparent; color: var(--ink);
  border-radius: 12px; padding: 8px 18px; font-size: 20px; cursor: pointer; margin: 0 6px;
  transition: transform .15s ease, border-color .15s ease;
}
.vote button:hover { transform: scale(1.1); border-color: var(--primary-soft); }
#voteThanks { margin-top: 10px; font-size: 14px; color: var(--ok); min-height: 20px; }

footer { text-align: center; color: var(--subtle); font-size: 13px; margin-top: 48px; }
footer a { color: var(--primary); text-decoration: none; }
footer a:hover { text-decoration: underline; }

/* ===== Note frequency table ===== */
.freq-table {
  width: 100%; border-collapse: collapse; margin-top: 12px; font-size: 14px;
}
.freq-table th, .freq-table td {
  padding: 9px 10px; text-align: left;
  border-bottom: 1px solid var(--border);
}
.freq-table th {
  color: var(--muted); font-weight: 600; font-size: 12px;
  text-transform: uppercase; letter-spacing: .3px;
}
.freq-table td { color: var(--ink); }
.freq-table td:last-child { color: var(--muted); font-size: 13px; }
.freq-table tr:hover td { background: color-mix(in srgb, var(--primary) 5%, transparent); }

/* ===== Related tools card grid ===== */
.tools-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px; margin-top: 16px;
}
.tool-card {
  display: flex; flex-direction: column; gap: 6px; text-decoration: none;
  background: var(--card); border: 1px solid var(--border); border-radius: 14px;
  padding: 16px; transition: all .2s ease;
}
.tool-card:hover {
  border-color: var(--primary-soft); transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(124, 58, 237, 0.1);
}
.tool-card .tc-icon { font-size: 28px; line-height: 1; }
.tool-card .tc-name { font-weight: 700; font-size: 15px; color: var(--ink); }
.tool-card .tc-desc { font-size: 12px; color: var(--muted); line-height: 1.4; }

/* Responsive */
@media (max-width: 680px) {
  :root { --wk: 30px; --bk: 18px; }
  .tool { padding: 18px; }
  .note-name { font-size: 56px; }
  h1 { font-size: clamp(26px, 7vw, 36px); }
  .tools-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 420px) {
  :root { --wk: 24px; --bk: 14px; }
  .settings { gap: 12px; }
}