/**
 * One light theme, deliberately off-white throughout: no pure #fff to glare
 * back, and no near-black. There is no prefers-color-scheme block — a dark
 * variant is not wanted here, so `color-scheme: light` is declared to stop the
 * browser painting the checkboxes and slider dark when the OS is in dark mode.
 */
:root {
  color-scheme: light;

  --bg: #eaecef;        /* page — the greyer of the two neutrals */
  --panel: #f8f9fa;     /* result box — lifts off the page without hitting white */
  --panel-soft: #dfe7d9;
  --border: #d8dce1;
  --text: #2c3238;      /* dark slate rather than black */
  --muted: #666e77;
  --accent: #c62842;
  --accent-text: #ffffff;
  --track: #7b8288;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06), 0 8px 24px rgba(16, 24, 40, 0.06);

  /* Darkened from their usual bright forms: on a light page the meter label is
     small bold text, and the cheerful versions of these fell under 3:1. */
  --weak: #c0392f;
  --fair: #945c0c;
  --good: #5d6a19;
  --strong: #3c6b34;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 14px;
  line-height: 1.5;
}

/* Layout */
.app {
  margin: 0 auto;
  max-width: 900px;
  padding: 32px 20px 40px;
}

.title {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 16px;
}

/* Result box */
.output {
  align-items: center;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  display: flex;
  gap: 16px;
  padding: 14px 14px 14px 22px;
}

.output__value {
  flex: 1;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 24px;
  font-weight: 600;
  letter-spacing: 0.5px;
  min-width: 0;
  /* 64 characters do not fit on a phone; wrap rather than overflow the box. */
  overflow-wrap: anywhere;
}

.output__actions {
  align-items: center;
  display: flex;
  flex-shrink: 0;
  gap: 12px;
}

/* Buttons */
.btn {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  cursor: pointer;
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  padding: 12px 20px;
  white-space: nowrap;
}

.btn--primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-text);
}

.btn--primary:hover {
  filter: brightness(1.08);
}

.icon-btn {
  background: none;
  border: none;
  border-radius: 8px;
  color: var(--muted);
  cursor: pointer;
  display: flex;
  padding: 8px;
}

.icon-btn:hover {
  color: var(--text);
}

.icon-btn:active svg {
  transform: rotate(-180deg);
}

.icon-btn svg {
  transition: transform 0.3s ease;
}

/* Strength meter */
.strength {
  align-items: center;
  display: flex;
  gap: 16px;
  padding: 14px 2px 0;
}

.meter {
  background: var(--border);
  border-radius: 999px;
  flex: 1;
  height: 7px;
  overflow: hidden;
}

.meter__fill {
  background: var(--strong);
  border-radius: inherit;
  height: 100%;
  transition: width 0.2s ease, background-color 0.2s ease;
  width: 100%;
}

.meter__fill--weak { background: var(--weak); }
.meter__fill--fair { background: var(--fair); }
.meter__fill--good { background: var(--good); }
.meter__fill--strong { background: var(--strong); }

.strength__label {
  align-items: center;
  display: flex;
  font-size: 14px;
  font-weight: 700;
  gap: 6px;
  margin: 0;
  white-space: nowrap;
}

.strength__label--weak { color: var(--weak); }
.strength__label--fair { color: var(--fair); }
.strength__label--good { color: var(--good); }
.strength__label--strong { color: var(--strong); }

/* Options */
.panel {
  background: var(--panel-soft);
  border-radius: var(--radius);
  margin-top: 18px;
  padding: 34px 28px;
  position: relative;
}

/* Ties the panel to the meter it explains. */
.panel::before {
  background: var(--panel-soft);
  content: '';
  height: 18px;
  left: 50%;
  position: absolute;
  top: -8px;
  transform: translateX(-50%) rotate(45deg);
  width: 18px;
}

.field {
  align-items: center;
  display: flex;
  flex-wrap: wrap;
  gap: 12px 32px;
}

.field + .field {
  margin-top: 28px;
}

.field__label {
  flex-shrink: 0;
  font-weight: 700;
  width: 170px;
}

/* Slider — the default control ignores most styling, so both engines are
   given explicit track and thumb rules. */
.slider {
  -webkit-appearance: none;
  appearance: none;
  background: none;
  cursor: pointer;
  flex: 1;
  height: 20px;
  min-width: 180px;
}

.slider:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
}

.slider::-webkit-slider-runnable-track {
  background: var(--track);
  border-radius: 999px;
  height: 6px;
}

.slider::-moz-range-track {
  background: var(--track);
  border-radius: 999px;
  height: 6px;
}

.slider::-moz-range-progress {
  background: var(--text);
  border-radius: 999px;
  height: 6px;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 50%;
  box-shadow: var(--shadow);
  height: 26px;
  margin-top: -10px; /* centres the thumb on a 6px track */
  width: 26px;
}

.slider::-moz-range-thumb {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 50%;
  box-shadow: var(--shadow);
  height: 26px;
  width: 26px;
}

/* Checkboxes */
.checks {
  display: flex;
  flex: 1;
  flex-wrap: wrap;
  gap: 12px 28px;
}

.check {
  align-items: center;
  cursor: pointer;
  display: flex;
  gap: 10px;
  user-select: none;
}

.check input {
  /* Green rather than --text: filled squares are the densest blocks of colour
     on the page, and at slate they read as black against the soft panel. */
  accent-color: var(--strong);
  cursor: pointer;
  height: 20px;
  margin: 0;
  width: 20px;
}

/* Toast */
.toast {
  background: var(--text);
  border-radius: 8px;
  bottom: 24px;
  color: var(--panel);
  font-size: 13px;
  left: 50%;
  opacity: 0;
  padding: 8px 16px;
  pointer-events: none;
  position: fixed;
  transform: translate(-50%, 8px);
  transition: opacity 0.18s ease, transform 0.18s ease;
}

.toast--show {
  opacity: 1;
  transform: translate(-50%, 0);
}

@media (prefers-reduced-motion: reduce) {
  .icon-btn svg,
  .meter__fill,
  .toast {
    transition: none;
  }
}

@media (max-width: 640px) {
  .app {
    padding: 20px 12px 32px;
  }

  .output {
    align-items: stretch;
    flex-direction: column;
    gap: 12px;
    padding: 16px;
  }

  .output__value {
    font-size: 20px;
  }

  .output__actions {
    justify-content: space-between;
  }

  .panel {
    padding: 24px 18px;
  }

  .field__label {
    width: auto;
  }
}