/* =========================================
   VARIABLES & RESET
   ========================================= */
:root {
  font-size: 10px; /* base 10px → 1rem = 10px */

  /* Paleta fría / azul */
  --clr-bg:           #080e1f;
  --clr-bg-card:      #0d1630;
  --clr-bg-card-2:    #111d3a;
  --clr-border:       rgba(99, 147, 255, 0.15);
  --clr-border-hover: rgba(99, 147, 255, 0.35);

  --clr-primary:      #4f8eff;
  --clr-primary-dark: #2b68e0;
  --clr-primary-glow: rgba(79, 142, 255, 0.35);

  --clr-accent:       #38bfff;

  --clr-text:         #e8eeff;
  --clr-text-muted:   #7a90c0;
  --clr-text-dim:     #4a5a80;

  /* Fortaleza */
  --clr-weak:         #ff4d6d;
  --clr-fair:         #ffa740;
  --clr-good:         #38bfff;
  --clr-strong:       #34d399;

  /* Misc */
  --radius-sm: 0.8rem;
  --radius-md: 1.4rem;
  --radius-lg: 2rem;

  --shadow-card: 0 8px 40px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 60px rgba(79, 142, 255, 0.12);

  --transition-fast: 150ms ease;
  --transition-mid:  250ms ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  font-size: 1.5rem;
  background-color: var(--clr-bg);
  color: var(--clr-text);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 4rem 1.6rem 6rem;
  position: relative;
  overflow-x: hidden;
}

/* =========================================
   BACKGROUND GLOW (decoración)
   ========================================= */
.bg-glow {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background:
    radial-gradient(ellipse 60% 40% at 20% 15%, rgba(79, 142, 255, 0.09) 0%, transparent 70%),
    radial-gradient(ellipse 50% 35% at 80% 75%, rgba(56, 191, 255, 0.07) 0%, transparent 70%);
}

/* =========================================
   ACCESIBILIDAD
   ========================================= */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

/* =========================================
   LAYOUT PRINCIPAL
   ========================================= */
.main {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 52rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* =========================================
   HEADER
   ========================================= */
.header {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.8rem;
  padding-bottom: 0.4rem;
}

.header__icon {
  width: 5.6rem;
  height: 5.6rem;
  background: linear-gradient(135deg, var(--clr-primary-dark), var(--clr-accent));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  box-shadow: 0 4px 20px var(--clr-primary-glow);
  margin-bottom: 0.4rem;
}

.header__title {
  font-size: 2.8rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  background: linear-gradient(120deg, var(--clr-text) 40%, var(--clr-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.header__subtitle {
  font-size: 1.4rem;
  color: var(--clr-text-muted);
}

/* =========================================
   CARD BASE
   ========================================= */
.card {
  background: var(--clr-bg-card);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-lg);
  padding: 2.4rem;
  box-shadow: var(--shadow-card);
  transition: border-color var(--transition-mid);
}

.card:hover {
  border-color: var(--clr-border-hover);
}

/* =========================================
   CARD: CONTRASEÑA
   ========================================= */
.password-display {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  background: var(--clr-bg-card-2);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-md);
  padding: 1.6rem 2rem;
  min-height: 6.4rem;
  transition: border-color var(--transition-mid);
}

.password-display:focus-within {
  border-color: var(--clr-primary);
  box-shadow: 0 0 0 3px var(--clr-primary-glow);
}

.password-display__text {
  flex: 1;
  font-size: 1.8rem;
  font-family: 'Consolas', 'Courier New', monospace;
  font-weight: 500;
  color: var(--clr-text);
  word-break: break-all;
  letter-spacing: 0.06em;
  transition: opacity var(--transition-fast);
  user-select: all;
}

.password-display__text--placeholder {
  color: var(--clr-text-dim);
  font-family: inherit;
  font-size: 1.5rem;
  letter-spacing: 0;
  user-select: none;
}

.password-display__text--hidden {
  letter-spacing: 0.18em;
  filter: blur(6px);
  user-select: none;
}

.password-display__actions {
  display: flex;
  gap: 0.6rem;
  flex-shrink: 0;
}

/* =========================================
   BOTONES ICONO
   ========================================= */
.btn-icon {
  width: 3.8rem;
  height: 3.8rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--clr-border);
  background: transparent;
  color: var(--clr-text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition:
    color var(--transition-fast),
    border-color var(--transition-fast),
    background-color var(--transition-fast),
    transform var(--transition-fast);
  position: relative;
  overflow: hidden;
}

.btn-icon:hover:not(:disabled) {
  color: var(--clr-primary);
  border-color: var(--clr-primary);
  background-color: rgba(79, 142, 255, 0.08);
}

.btn-icon:active:not(:disabled) {
  transform: scale(0.92);
}

.btn-icon:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

/* Estado "copiado" del botón copy */
.btn-icon--copied {
  color: var(--clr-strong) !important;
  border-color: var(--clr-strong) !important;
  background-color: rgba(52, 211, 153, 0.1) !important;
}

/* Iconos dentro del botón */
.icon {
  position: absolute;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

/* Visibilidad btn-toggle */
#btn-toggle-visibility .icon--eye-open  { opacity: 1;  transform: scale(1); }
#btn-toggle-visibility .icon--eye-closed { opacity: 0; transform: scale(0.7); }

#btn-toggle-visibility.is-hidden .icon--eye-open  { opacity: 0; transform: scale(0.7); }
#btn-toggle-visibility.is-hidden .icon--eye-closed { opacity: 1; transform: scale(1); }

/* Copiar btn */
#btn-copy .icon--copy  { opacity: 1;  transform: scale(1); }
#btn-copy .icon--check { opacity: 0;  transform: scale(0.7); }

#btn-copy.btn-icon--copied .icon--copy  { opacity: 0;  transform: scale(0.7); }
#btn-copy.btn-icon--copied .icon--check { opacity: 1;  transform: scale(1); }

/* =========================================
   INDICADOR DE FORTALEZA
   ========================================= */
.strength {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  margin-top: 1.6rem;
}

.strength__bars {
  display: flex;
  gap: 0.5rem;
  flex: 1;
}

.strength__bar {
  flex: 1;
  height: 0.5rem;
  border-radius: 10rem;
  background: var(--clr-bg-card-2);
  border: 1px solid var(--clr-border);
  transition: background-color var(--transition-mid), border-color var(--transition-mid);
}

.strength__bar--weak   { background-color: var(--clr-weak);   border-color: var(--clr-weak); }
.strength__bar--fair   { background-color: var(--clr-fair);   border-color: var(--clr-fair); }
.strength__bar--good   { background-color: var(--clr-good);   border-color: var(--clr-good); }
.strength__bar--strong { background-color: var(--clr-strong); border-color: var(--clr-strong); }

.strength__label {
  font-size: 1.2rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  min-width: 7rem;
  text-align: right;
  color: var(--clr-text-dim);
  transition: color var(--transition-mid);
}

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

/* =========================================
   TOAST
   ========================================= */
.toast {
  position: absolute;
  bottom: -0.4rem;
  left: 50%;
  transform: translateX(-50%) translateY(110%);
  background: var(--clr-strong);
  color: #082a1f;
  font-size: 1.3rem;
  font-weight: 600;
  padding: 0.8rem 1.8rem;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition-mid), transform var(--transition-mid);
  z-index: 10;
}

.toast--visible {
  opacity: 1;
  transform: translateX(-50%) translateY(100%);
}

/* El card de password necesita position relative para el toast */
.password-card {
  position: relative;
  overflow: visible;
}

/* =========================================
   CARD: CONFIGURACIÓN
   ========================================= */
.config-card__title {
  font-size: 1.6rem;
  font-weight: 600;
  color: var(--clr-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 2.4rem;
}

.config-form {
  display: flex;
  flex-direction: column;
  gap: 2.8rem;
}

/* =========================================
   FIELDSET
   ========================================= */
.fieldset {
  border: none;
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.fieldset__legend {
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--clr-text);
  margin-bottom: 0.6rem;
}

/* =========================================
   CONTROL DE LONGITUD
   ========================================= */
.length-control {
  display: flex;
  align-items: center;
  gap: 1.6rem;
}

.length-control__slider {
  flex: 1;
  -webkit-appearance: none;
  appearance: none;
  height: 0.5rem;
  border-radius: 10rem;
  background: var(--clr-bg-card-2);
  border: 1px solid var(--clr-border);
  outline: none;
  cursor: pointer;
  position: relative;
  /* Degradado dinámico se pone via JS en --slider-pct */
  background-image: linear-gradient(
    to right,
    var(--clr-primary) 0%,
    var(--clr-primary) var(--slider-pct, 20%),
    transparent var(--slider-pct, 20%)
  );
  transition: background-image var(--transition-fast);
}

.length-control__slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--clr-primary);
  border: 3px solid var(--clr-bg);
  box-shadow: 0 0 0 2px var(--clr-primary), 0 2px 8px var(--clr-primary-glow);
  cursor: grab;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.length-control__slider::-webkit-slider-thumb:active {
  cursor: grabbing;
  transform: scale(1.2);
  box-shadow: 0 0 0 4px var(--clr-primary-glow), 0 2px 12px var(--clr-primary-glow);
}

.length-control__slider::-moz-range-thumb {
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--clr-primary);
  border: 3px solid var(--clr-bg);
  cursor: grab;
}

.length-control__value {
  font-size: 2rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--clr-primary);
  min-width: 3.2rem;
  text-align: center;
}

.length-control__labels {
  display: flex;
  justify-content: space-between;
  font-size: 1.1rem;
  color: var(--clr-text-dim);
  padding: 0 0.2rem;
}

/* =========================================
   OPCIONES TOGGLE (switches)
   ========================================= */
.options-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}

.option-toggle {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  background: var(--clr-bg-card-2);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-md);
  padding: 1.4rem 1.6rem;
  cursor: pointer;
  transition:
    border-color var(--transition-fast),
    background-color var(--transition-fast);
  user-select: none;
}

.option-toggle:hover {
  border-color: var(--clr-border-hover);
  background: rgba(79, 142, 255, 0.04);
}

.option-toggle:has(.option-toggle__checkbox:checked) {
  border-color: rgba(79, 142, 255, 0.4);
  background: rgba(79, 142, 255, 0.06);
}

.option-toggle__checkbox {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

/* Track del switch */
.option-toggle__track {
  position: relative;
  width: 4rem;
  height: 2.2rem;
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 10rem;
  flex-shrink: 0;
  transition: background-color var(--transition-fast), border-color var(--transition-fast);
}

.option-toggle__track::after {
  content: '';
  position: absolute;
  top: 0.3rem;
  left: 0.3rem;
  width: 1.4rem;
  height: 1.4rem;
  background: var(--clr-text-dim);
  border-radius: 50%;
  transition: transform var(--transition-fast), background-color var(--transition-fast);
}

.option-toggle__checkbox:checked + .option-toggle__track {
  background: var(--clr-primary-dark);
  border-color: var(--clr-primary);
}

.option-toggle__checkbox:checked + .option-toggle__track::after {
  background: #fff;
  transform: translateX(1.8rem);
}

.option-toggle__checkbox:focus-visible + .option-toggle__track {
  outline: 2px solid var(--clr-primary);
  outline-offset: 3px;
}

.option-toggle__content {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.option-toggle__label {
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--clr-text);
}

.option-toggle__example {
  font-size: 1.1rem;
  color: var(--clr-text-dim);
  font-family: 'Consolas', 'Courier New', monospace;
}

/* =========================================
   MENSAJE DE VALIDACIÓN
   ========================================= */
.validation-msg {
  font-size: 1.3rem;
  color: var(--clr-weak);
  min-height: 1.8rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  opacity: 0;
  transform: translateY(-0.4rem);
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}

.validation-msg--visible {
  opacity: 1;
  transform: translateY(0);
}

/* =========================================
   BOTÓN GENERAR
   ========================================= */
.btn-generate {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  width: 100%;
  padding: 1.5rem 2rem;
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: #fff;
  background: linear-gradient(135deg, var(--clr-primary-dark) 0%, var(--clr-primary) 60%, var(--clr-accent) 100%);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  box-shadow: 0 4px 20px var(--clr-primary-glow);
  transition:
    box-shadow var(--transition-fast),
    transform var(--transition-fast),
    filter var(--transition-fast);
}

.btn-generate::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.12), transparent);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.btn-generate:hover {
  box-shadow: 0 6px 28px var(--clr-primary-glow);
  transform: translateY(-1px);
  filter: brightness(1.08);
}

.btn-generate:hover::before {
  opacity: 1;
}

.btn-generate:active {
  transform: translateY(0) scale(0.98);
  box-shadow: 0 2px 10px var(--clr-primary-glow);
}

/* Animación de pulso en el botón */
.btn-generate--pulse {
  animation: pulse-btn 0.3s ease;
}

@keyframes pulse-btn {
  0%   { transform: scale(1); }
  40%  { transform: scale(0.96); }
  100% { transform: scale(1); }
}

/* =========================================
   FOOTER
   ========================================= */
.footer {
  position: relative;
  z-index: 1;
  margin-top: 3rem;
  text-align: center;
}

.footer__text {
  font-size: 1.2rem;
  color: var(--clr-text-dim);
}

/* =========================================
   RESPONSIVE
   ========================================= */
@media (max-width: 520px) {
  body {
    padding: 2.4rem 1.2rem 4rem;
  }

  .header__title {
    font-size: 2.2rem;
  }

  .card {
    padding: 2rem 1.6rem;
  }

  .options-grid {
    grid-template-columns: 1fr;
  }

  .password-display__text {
    font-size: 1.5rem;
  }
}

@media (max-width: 360px) {
  .header__title {
    font-size: 2rem;
  }

  .length-control__value {
    font-size: 1.8rem;
  }
}