/* ============================================================
   RESET Y BASE
   ============================================================ */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  /* Paleta de colores fríos/azules */
  --color-bg:           #0d1117;
  --color-surface:      #161b27;
  --color-surface-alt:  #1e2636;
  --color-border:       #2a3550;
  --color-primary:      #4f8ef7;
  --color-primary-dark: #3a6fd8;
  --color-primary-glow: rgba(79, 142, 247, 0.18);
  --color-accent:       #60c4f8;
  --color-success:      #34d399;
  --color-danger:       #f87171;
  --color-text:         #e2e8f4;
  --color-text-muted:   #7b91b8;
  --color-text-dim:     #4a5e80;

  /* Tipografía */
  --font-family: 'Inter', 'Segoe UI', system-ui, sans-serif;

  /* Espaciado */
  --radius-sm:  0.6rem;
  --radius-md:  1rem;
  --radius-lg:  1.6rem;
  --radius-xl:  2.4rem;

  /* Sombras */
  --shadow-card: 0 0.4rem 3.2rem rgba(0, 0, 0, 0.45);
  --shadow-btn:  0 0.2rem 1.2rem rgba(79, 142, 247, 0.3);

  /* Transiciones */
  --transition: 0.22s ease;
}

html {
  font-size: 10px; /* Base = 10px → 1rem = 10px */
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: 1.6rem;
  background-color: var(--color-bg);
  color: var(--color-text);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2.4rem 1.6rem;
  line-height: 1.5;
}

/* ============================================================
   LAYOUT PRINCIPAL
   ============================================================ */
.app {
  width: 100%;
  max-width: 52rem;
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* ============================================================
   HEADER
   ============================================================ */
.app__header {
  text-align: center;
  margin-bottom: 3.2rem;
}

.app__logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 6.4rem;
  height: 6.4rem;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-lg);
  margin-bottom: 1.6rem;
  box-shadow: 0 0.4rem 2rem rgba(79, 142, 247, 0.4);
}

.app__logo svg {
  width: 3.2rem;
  height: 3.2rem;
  fill: none;
  stroke: #fff;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.app__title {
  font-size: 2.8rem;
  font-weight: 700;
  letter-spacing: -0.04em;
  background: linear-gradient(120deg, #e2e8f4 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.6rem;
}

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

/* ============================================================
   CARD
   ============================================================ */
.card {
  background: var(--color-surface);
  border: 0.1rem solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: 3.2rem;
  box-shadow: var(--shadow-card);
}

/* ============================================================
   RESULTADO / CONTRASEÑA
   ============================================================ */
.result {
  margin-bottom: 2.4rem;
}

.result__label {
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: 0.8rem;
  display: block;
}

.result__box {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  background: var(--color-bg);
  border: 0.1rem solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.4rem 1.6rem;
  transition: border-color var(--transition);
}

.result__box:focus-within {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 0.3rem var(--color-primary-glow);
}

.result__password {
  flex: 1;
  font-family: 'Courier New', 'Consolas', monospace;
  font-size: 1.8rem;
  font-weight: 600;
  color: var(--color-text);
  background: transparent;
  border: none;
  outline: none;
  letter-spacing: 0.08em;
  word-break: break-all;
  min-height: 2.6rem;
  cursor: default;
  user-select: none;
  /* Estado vacío */
  color: var(--color-text-dim);
}

.result__password.has-value {
  color: var(--color-text);
}

/* Contraseña oculta */
.result__password.is-hidden {
  -webkit-text-security: disc;
  font-size: 2rem;
  letter-spacing: 0.18em;
}

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

/* ============================================================
   BOTONES ICONO (Copiar / Mostrar)
   ============================================================ */
.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 4rem;
  height: 4rem;
  border-radius: var(--radius-sm);
  border: 0.1rem solid var(--color-border);
  background: var(--color-surface-alt);
  color: var(--color-text-muted);
  cursor: pointer;
  transition: background var(--transition), color var(--transition),
              border-color var(--transition), transform var(--transition);
  position: relative;
}

.btn-icon:hover {
  background: var(--color-primary-glow);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: scale(1.08);
}

.btn-icon:active {
  transform: scale(0.96);
}

/* Variante con emoji en lugar de SVG */
.btn-icon--emoji {
  font-size: 1.8rem;
  line-height: 1;
}

.btn-icon svg {
  width: 1.8rem;
  height: 1.8rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  pointer-events: none;
}

/* Tooltip de feedback */
.btn-icon__tooltip {
  position: absolute;
  bottom: calc(100% + 0.8rem);
  left: 50%;
  transform: translateX(-50%) translateY(0.4rem);
  background: var(--color-success);
  color: #fff;
  font-size: 1.1rem;
  font-weight: 600;
  padding: 0.4rem 0.8rem;
  border-radius: var(--radius-sm);
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition), transform var(--transition);
}

.btn-icon__tooltip.is-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ============================================================
   INDICADOR DE FORTALEZA
   ============================================================ */
.strength {
  margin-bottom: 2.4rem;
}

.strength__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.8rem;
}

.strength__label {
  font-size: 1.2rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.strength__text {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-text-dim);
  transition: color var(--transition);
}

.strength__bar-track {
  height: 0.6rem;
  background: var(--color-bg);
  border-radius: 99rem;
  overflow: hidden;
  border: 0.1rem solid var(--color-border);
}

.strength__bar-fill {
  height: 100%;
  border-radius: 99rem;
  width: 0%;
  transition: width 0.35s ease, background-color 0.35s ease;
  background-color: var(--color-text-dim);
}

/* Niveles de fortaleza */
.strength__bar-fill[data-level="1"] { width: 25%; background-color: var(--color-danger); }
.strength__bar-fill[data-level="2"] { width: 50%; background-color: #f59e0b; }
.strength__bar-fill[data-level="3"] { width: 75%; background-color: #60c4f8; }
.strength__bar-fill[data-level="4"] { width: 100%; background-color: var(--color-success); }

.strength__text[data-level="1"] { color: var(--color-danger); }
.strength__text[data-level="2"] { color: #f59e0b; }
.strength__text[data-level="3"] { color: #60c4f8; }
.strength__text[data-level="4"] { color: var(--color-success); }

/* ============================================================
   SEPARADOR
   ============================================================ */
.divider {
  height: 0.1rem;
  background: var(--color-border);
  margin: 2.4rem 0;
}

/* ============================================================
   LONGITUD (SLIDER)
   ============================================================ */
.length-control {
  margin-bottom: 2.4rem;
}

.length-control__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.2rem;
}

.length-control__label {
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--color-text);
}

.length-control__value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
  min-width: 3rem;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* Slider personalizado */
.slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 0.6rem;
  border-radius: 99rem;
  background: linear-gradient(
    to right,
    var(--color-primary) 0%,
    var(--color-primary) var(--slider-percent, 53%),
    var(--color-bg) var(--slider-percent, 53%),
    var(--color-bg) 100%
  );
  outline: none;
  cursor: pointer;
  border: 0.1rem solid var(--color-border);
  transition: background var(--transition);
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--color-primary);
  border: 0.2rem solid #fff;
  box-shadow: 0 0 0.6rem rgba(79, 142, 247, 0.5), var(--shadow-btn);
  transition: transform var(--transition), box-shadow var(--transition);
  cursor: pointer;
}

.slider::-moz-range-thumb {
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--color-primary);
  border: 0.2rem solid #fff;
  box-shadow: 0 0 0.6rem rgba(79, 142, 247, 0.5), var(--shadow-btn);
  cursor: pointer;
}

.slider:hover::-webkit-slider-thumb {
  transform: scale(1.15);
  box-shadow: 0 0 1.2rem rgba(79, 142, 247, 0.7), var(--shadow-btn);
}

.slider:hover::-moz-range-thumb {
  transform: scale(1.15);
}

/* ============================================================
   OPCIONES (CHECKBOXES)
   ============================================================ */
.options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
  margin-bottom: 2.8rem;
}

.option {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  padding: 1.2rem 1.4rem;
  background: var(--color-bg);
  border: 0.1rem solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition),
              transform var(--transition);
  user-select: none;
}

.option:hover {
  background: var(--color-primary-glow);
  border-color: var(--color-primary);
  transform: translateY(-0.1rem);
}

.option input[type="checkbox"] {
  display: none;
}

.option__check {
  width: 2rem;
  height: 2rem;
  border-radius: 0.5rem;
  border: 0.2rem solid var(--color-border);
  background: var(--color-surface);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background var(--transition), border-color var(--transition);
}

.option__check svg {
  width: 1.2rem;
  height: 1.2rem;
  stroke: #fff;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
  fill: none;
  opacity: 0;
  transform: scale(0.5);
  transition: opacity var(--transition), transform var(--transition);
}

.option input[type="checkbox"]:checked + .option__check {
  background: var(--color-primary);
  border-color: var(--color-primary);
}

.option input[type="checkbox"]:checked + .option__check svg {
  opacity: 1;
  transform: scale(1);
}

.option__text {
  font-size: 1.4rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--transition);
}

.option:has(input[type="checkbox"]:checked) .option__text {
  color: var(--color-text);
}

.option:has(input[type="checkbox"]:checked) {
  border-color: var(--color-primary);
  background: var(--color-primary-glow);
}

/* ============================================================
   ACCIONES DEL FORMULARIO (fila de botones)
   ============================================================ */
.form-actions {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1.2rem;
}

/* ============================================================
   BOTÓN COPIAR (secundario)
   ============================================================ */
.btn-copy {
  padding: 1.6rem 2rem;
  border: 0.15rem solid var(--color-primary);
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--color-primary);
  font-family: var(--font-family);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  white-space: nowrap;
  position: relative;
  overflow: visible;
  transition: background var(--transition), color var(--transition),
              border-color var(--transition), transform var(--transition),
              box-shadow var(--transition);
}

/* Estado "copiado": borde y texto verde */
.btn-copy.is-copied {
  border-color: var(--color-success);
  color: var(--color-success);
}

.btn-copy:hover {
  background: var(--color-primary-glow);
  transform: translateY(-0.2rem);
  box-shadow: 0 0.4rem 1.4rem rgba(79, 142, 247, 0.25);
}

.btn-copy:active {
  transform: translateY(0);
  box-shadow: none;
}

.btn-copy svg {
  width: 1.8rem;
  height: 1.8rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  pointer-events: none;
  flex-shrink: 0;
}

/* ============================================================
   BOTÓN GENERAR (primario)
   ============================================================ */
.btn-generate {
  padding: 1.6rem;
  border: none;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  color: #fff;
  font-family: var(--font-family);
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  box-shadow: var(--shadow-btn);
  transition: opacity var(--transition), transform var(--transition),
              box-shadow var(--transition);
}

.btn-generate:hover {
  opacity: 0.92;
  transform: translateY(-0.2rem);
  box-shadow: 0 0.6rem 2rem rgba(79, 142, 247, 0.45);
}

.btn-generate:active {
  transform: translateY(0);
  box-shadow: var(--shadow-btn);
}

.btn-generate svg {
  width: 2rem;
  height: 2rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.2;
  stroke-linecap: round;
  stroke-linejoin: round;
  pointer-events: none;
}

/* Animación de rotación al generar */
.btn-generate.is-generating svg {
  animation: spin 0.5s linear;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ============================================================
   ALERTA DE ERROR
   ============================================================ */
.alert {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.2rem 1.6rem;
  background: rgba(248, 113, 113, 0.12);
  border: 0.1rem solid rgba(248, 113, 113, 0.4);
  border-radius: var(--radius-md);
  margin-bottom: 2rem;
  color: var(--color-danger);
  font-size: 1.4rem;
  font-weight: 500;
}

.alert svg {
  width: 1.8rem;
  height: 1.8rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex-shrink: 0;
}

.alert[hidden] {
  display: none;
}

/* ============================================================
   FOOTER
   ============================================================ */
.app__footer {
  text-align: center;
  margin-top: 2.4rem;
  font-size: 1.2rem;
  color: var(--color-text-dim);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 480px) {
  .card {
    padding: 2.4rem 2rem;
  }

  .app__title {
    font-size: 2.2rem;
  }

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

  .result__password {
    font-size: 1.5rem;
  }

  /* Botones en columna en móvil */
  .form-actions {
    grid-template-columns: 1fr;
  }

  .btn-copy {
    justify-content: center;
  }
}

@media (max-width: 360px) {
  html {
    font-size: 9px;
  }
}