/* ========== Design Tokens & Global Reset ========== */
:root {
  /* Colors */
  --c-bg: hsl(240, 10%, 12%);
  --c-bg-alt: hsl(240, 10%, 15%);
  --c-primary: hsl(195, 100%, 50%);
  --c-secondary: hsl(340, 100%, 65%);
  --c-accent: hsl(45, 100%, 50%);
  --c-text: hsl(0, 0%, 98%);
  --c-text-alt: hsl(0, 0%, 80%);

  /* Gradients */
  --g-bg: linear-gradient(145deg, var(--c-bg-alt), var(--c-bg));
  --g-btn-primary: linear-gradient(145deg, var(--c-primary), var(--c-secondary));
  --g-btn-hover: linear-gradient(145deg, var(--c-secondary), var(--c-primary));

  /* Typography */
  --fs-xl: clamp(2rem, 5vw, 3.5rem);
  --fs-lg: clamp(1.25rem, 3vw, 2rem);
  --fs-md: clamp(1rem, 2.5vw, 1.25rem);
  --fs-sm: clamp(0.875rem, 2vw, 1rem);
  --fw-regular: 400;
  --fw-bold: 600;

  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;

  /* Effects */
  --radius: 1.5rem;
  --shadow-light: 0 8px 20px rgba(0,0,0,0.2);
  --shadow-deep: 0 20px 50px rgba(0,0,0,0.4);
  --transition: all 0.3s var(--ease);
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
}
*, *::before, *::after {
  margin: 0; padding: 0; box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
}
body {
  font-family: 'Poppins', sans-serif;
  background: var(--g-bg);
  color: var(--c-text);
  min-height: 100vh;
  display: flex; align-items: center; justify-content: center;
  overflow: hidden;
  transition: background var(--transition), color var(--transition);
}
@media (prefers-color-scheme: light) {
  :root {
    --c-bg: hsl(0, 0%, 98%);
    --c-bg-alt: hsl(0, 0%, 95%);
    --c-text: hsl(240, 10%, 12%);
    --g-bg: linear-gradient(145deg, var(--c-bg-alt), var(--c-bg));
  }
}

/* ========== Utility Classes ========== */
.hidden { display: none !important; }
.flex { display: flex; }
.center { justify-content: center; align-items: center; }
.transition { transition: var(--transition); }

/* ======= Preloader ======= */
.preloader {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: #1f1c2c;
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  transition: opacity 0.6s ease;
}

.loader {
  width: 80px;
  height: 80px;
  border: 6px solid rgba(255, 255, 255, 0.3);
  border-top-color: #00c6ff;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

/* Spin Animation */
@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}


/* ========== Main Container ========== */
.main-container {
  width: min(90%, 600px);
  padding: var(--space-xl);
  background: var(--g-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-deep);
  text-align: center;
  transition: transform var(--transition), box-shadow var(--transition);
}
.main-container:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-deep), inset 0 0 30px rgba(0,0,0,0.2);
}

/* ========== Header ========== */
.header h1 {
  font-size: var(--fs-xl);
  font-weight: var(--fw-bold);
  margin-bottom: var(--space-md);
  background: linear-gradient(90deg, var(--c-text), var(--c-accent));
  -webkit-background-clip: text;
  color: transparent;
  letter-spacing: 1px;
  text-shadow: 0 2px 8px rgba(0,0,0,0.3);
}
.header p {
  font-size: var(--fs-md);
  color: var(--c-text-alt);
  margin-bottom: var(--space-lg);
  line-height: 1.4;
}

/* ========== Tabs ========== */
.tabs {
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  margin-top: var(--space-lg);
}
.tab-button {
  padding: var(--space-sm) var(--space-lg);
  font-size: var(--fs-sm);
  font-weight: var(--fw-bold);
  border: none;
  border-radius: 2rem;
  background: var(--g-btn-primary);
  color: #fff;
  cursor: pointer;
  box-shadow: var(--shadow-light);
  transition: var(--transition);
  position: relative;
}
.tab-button::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  box-shadow: 0 0 0 0 rgba(255,255,255,0.3);
  transition: box-shadow var(--transition);
}
.tab-button:hover {
  background: var(--g-btn-hover);
}
.tab-button:hover::after {
  box-shadow: 0 0 10px 2px rgba(255,255,255,0.3);
}
.tab-button.active {
  background: #fff;
  color: var(--c-primary);
  box-shadow: inset 0 0 0 2px var(--c-primary);
}

/* ========== Tab Content ========== */
.tab-content {
  display: none;
  margin-top: var(--space-lg);
  padding: var(--space-lg);
  backdrop-filter: blur(12px);
  background: rgba(255,255,255,0.05);
  border-radius: var(--radius);
  animation: fadeInUp 0.5s var(--ease) both;
}
.tab-content.active { display: block; }
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ========== Password Box ========== */
.password-box {
  margin-top: var(--space-lg);
}
.password-output {
  width: 100%;
  padding: var(--space-md);
  background: #fafafa;
  border: 2px solid var(--c-secondary);
  border-radius: var(--radius);
  font-size: var(--fs-md);
  font-weight: var(--fw-bold);
  color: #333;
  word-break: break-word;
  box-shadow: inset 0 5px 15px rgba(0,0,0,0.1);
  transition: background var(--transition), transform var(--transition);
}
.password-output:focus {
  outline: none;
  background: #fff;
  transform: scale(1.02);
}

/* ========== Generate Button ========== */
.generate-btn {
  width: 100%;
  margin-top: var(--space-lg);
  padding: var(--space-md);
  font-size: var(--fs-md);
  font-weight: var(--fw-bold);
  border: none;
  border-radius: 3rem;
  background: var(--g-btn-primary);
  color: #fff;
  cursor: pointer;
  box-shadow: var(--shadow-deep);
  transition: var(--transition);
}
.generate-btn:hover {
  background: var(--g-btn-hover);
  transform: translateY(-3px) scale(1.02);
  box-shadow: 0 25px 60px rgba(0,0,0,0.4);
}
.generate-btn:active {
  transform: translateY(0) scale(0.98);
}

/* ========== Settings ========== */
.settings {
  margin-top: var(--space-lg);
  font-size: var(--fs-sm);
  color: var(--c-text-alt);
  text-align: left;
}
.settings label {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}
.settings input[type="number"],
.settings input[type="checkbox"] {
  accent-color: var(--c-primary);
  cursor: pointer;
}

/* ========== Footer ========== */
.footer {
  margin-top: var(--space-xl);
  font-size: var(--fs-sm);
  color: var(--c-text-alt);
}
.footer a {
  color: var(--c-primary);
  text-decoration: none;
  font-weight: var(--fw-bold);
  transition: color var(--transition);
}
.footer a:hover {
  color: var(--c-secondary);
  text-decoration: underline;
}

/* ========== Responsive ========== */
@media (max-width: 480px) {
  .header h1 { font-size: clamp(1.75rem, 6vw, 2.5rem); }
  .main-container { padding: var(--space-lg); }
  .tabs { flex-wrap: wrap; gap: var(--space-sm); }
  .tab-button { padding: var(--space-sm) var(--space-md); font-size: var(--fs-sm); }
  .password-output { font-size: var(--fs-sm); }
}