/* =========================================================
   ROOT VARIABLES
========================================================= */

:root {
  --bg: #0f172a;
  --panel: #111827;
  --accent: #22c55e;
  --accent-2: #38bdf8;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --danger: #ef4444;
  --warn: #f59e0b;
  --border: rgba(255, 255, 255, 0.08);
  --soft-bg: rgba(255, 255, 255, 0.03);
}

/* =========================================================
   GLOBAL RESET
========================================================= */

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

/* =========================================================
   BODY
========================================================= */

body {
  margin: 0;
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    Segoe UI,
    Roboto,
    Ubuntu,
    Cantarell,
    Noto Sans,
    Arial,
    "Apple Color Emoji",
    "Segoe UI Emoji";
  background:
    radial-gradient(1200px 600px at 60% -20%, #172554 0%, #0b1029 60%, #050816 100%),
    var(--bg);
  color: var(--text);
  min-height: 100vh;
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding: 24px;
}

/* =========================================================
   MAIN CARD
========================================================= */

.card {
  width: 100%;
  max-width: 920px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.03), rgba(255, 255, 255, 0.02));
  border: 1px solid var(--border);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
}

/* =========================================================
   HEADER
========================================================= */

header {
  padding: 20px 24px;
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}

header h1 {
  margin: 0;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.3px;
  color: #f8fbff;
}

header .sub {
  font-size: 13px;
  color: var(--muted);
}

/* =========================================================
   MAIN GRID
========================================================= */

.grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 20px;
  padding: 20px;
}

/* =========================================================
   PANELS
========================================================= */

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
}

/* =========================================================
   METRICS GRID
========================================================= */

.metrics {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin-top: 12px;
}

/* =========================================================
   METRIC CARD
========================================================= */

.metric {
  background: var(--soft-bg);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 12px;
  padding: 14px;
  transition:
    transform 0.2s ease,
    border-color 0.2s ease,
    background 0.2s ease;
  will-change: transform;
}

.metric:hover {
  transform: translateY(-2px);
  border-color: rgba(255, 255, 255, 0.12);
  background: rgba(255, 255, 255, 0.05);
}

.metric .label {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.4px;
}

.metric .value {
  font-size: clamp(20px, 3vw, 28px);
  font-weight: 700;
  line-height: 1.1;
  color: #f8fafc;
}

.metric.live .value {
  color: #67e8f9;
  text-shadow: 0 0 14px rgba(103, 232, 249, 0.35);
}

.metric.peak .value {
  color: #86efac;
}

/* =========================================================
   CONTROLS
========================================================= */

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

/* =========================================================
   BUTTONS + SELECT
========================================================= */

button,
select {
  appearance: none;
  border: none;
  outline: none;
  border-radius: 12px;
  padding: 10px 16px;
  font-weight: 700;
  cursor: pointer;
  transition:
    transform 0.08s ease,
    box-shadow 0.2s ease,
    opacity 0.2s ease,
    filter 0.2s ease;
}

button {
  color: #051018;
}

select {
  background: rgba(255, 255, 255, 0.08);
  color: #e2e8f0;
  border: 1px solid rgba(255, 255, 255, 0.12);
}

button:hover:not(:disabled),
select:hover {
  filter: brightness(1.05);
}

button:active:not(:disabled) {
  transform: scale(0.98);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

button:focus-visible,
select:focus-visible {
  outline: 2px solid var(--accent-2);
  outline-offset: 2px;
}

/* =========================================================
   BUTTON VARIANTS
========================================================= */

.btn-start {
  background: linear-gradient(135deg, #22c55e, #16a34a);
  box-shadow: 0 6px 20px rgba(34, 197, 94, 0.35);
}

.btn-start:hover:not(:disabled) {
  background: linear-gradient(135deg, #4ade80, #22c55e);
}

.btn-stop {
  background: linear-gradient(135deg, #fb7185, #ef4444);
  box-shadow: 0 6px 20px rgba(239, 68, 68, 0.35);
}

.btn-stop:hover:not(:disabled) {
  background: linear-gradient(135deg, #fda4af, #fb7185);
}

.btn-reset {
  background: linear-gradient(135deg, #93c5fd, #60a5fa);
  box-shadow: 0 6px 20px rgba(96, 165, 250, 0.35);
}

.btn-reset:hover:not(:disabled) {
  background: linear-gradient(135deg, #bfdbfe, #93c5fd);
}

#resetBestBtn {
  background: linear-gradient(135deg, #f59e0b, #d97706);
  color: #1f1300;
  box-shadow: 0 6px 20px rgba(245, 158, 11, 0.35);
}

#resetBestBtn:hover:not(:disabled) {
  background: linear-gradient(135deg, #fbbf24, #f59e0b);
}

/* =========================================================
   MAIN CLICK BUTTON
========================================================= */

.btn-click {
  width: 100%;
  margin-top: 16px;
  padding: 18px 16px;
  font-size: 20px;
  background: linear-gradient(135deg, #38bdf8, #06b6d4);
  color: #001219;
  box-shadow: 0 12px 30px rgba(56, 189, 248, 0.35);
  will-change: transform;
}

.btn-click:hover:not(:disabled) {
  background: linear-gradient(135deg, #67e8f9, #22d3ee);
}

/* =========================================================
   INTERACTION POLISH
========================================================= */

button,
.btn-click,
canvas {
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

/* =========================================================
   HINT TEXT
========================================================= */

.hint {
  margin-top: 10px;
  font-size: 12px;
  color: var(--muted);
  line-height: 1.5;
}

/* =========================================================
   CHART AREA
========================================================= */

.chart-wrap {
  position: relative;
  height: 320px;
  display: grid;
  grid-template-rows: auto 1fr;
  gap: 10px;
}

/* =========================================================
   CHART HEADER
========================================================= */

.chart-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
}

.chart-title {
  font-weight: 700;
  letter-spacing: 0.3px;
}

/* =========================================================
   LEGEND
========================================================= */

.legend {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  font-size: 12px;
  color: var(--muted);
}

.legend .swatch {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  display: inline-block;
  margin-right: 6px;
}

/* =========================================================
   CANVAS
========================================================= */

canvas {
  width: 100%;
  height: 100%;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.02), rgba(255, 255, 255, 0.01));
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 12px;
}

/* =========================================================
   FOOTER
========================================================= */

footer {
  padding: 14px 20px;
  border-top: 1px solid var(--border);
  font-size: 12px;
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

/* =========================================================
   KEYBOARD KEY STYLE
========================================================= */

code.kb {
  background: rgba(255, 255, 255, 0.08);
  padding: 2px 6px;
  border-radius: 6px;
  color: #e2e8f0;
  font-weight: 700;
}

/* =========================================================
   TABLET RESPONSIVE
========================================================= */

@media (max-width: 860px) {
  .grid {
    grid-template-columns: 1fr;
  }

  .chart-wrap {
    height: 300px;
  }
}

/* =========================================================
   MOBILE RESPONSIVE
========================================================= */

@media (max-width: 640px) {
  body {
    padding: 14px;
  }

  .card {
    border-radius: 14px;
  }

  header {
    flex-direction: column;
    align-items: flex-start;
    padding: 18px;
  }

  header h1 {
    font-size: 18px;
  }

  .grid {
    padding: 14px;
    gap: 14px;
  }

  .panel {
    padding: 14px;
  }

  .metrics {
    grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
    gap: 10px;
  }

  .metric {
    padding: 12px;
  }

  .metric .value {
    font-size: 22px;
  }

  .controls {
    flex-direction: column;
  }

  .controls button,
  .controls select {
    width: 100%;
  }

  .btn-click {
    padding: 16px;
    font-size: 18px;
  }

  .chart-wrap {
    height: 260px;
  }

  footer {
    flex-direction: column;
    align-items: flex-start;
    padding: 12px 16px;
  }
}

/* =========================================================
   SMALL PHONE OPTIMIZATION
========================================================= */

@media (max-width: 420px) {
  .metrics {
    grid-template-columns: 1fr 1fr;
  }

  .metric .label {
    font-size: 11px;
  }

  .metric .value {
    font-size: 20px;
  }

  .btn-click {
    font-size: 17px;
  }

  .chart-wrap {
    height: 220px;
  }
}

/* =========================================================
   REDUCED MOTION
========================================================= */

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