/* ===== CSS CUSTOM PROPERTIES ===== */
:root {
  --bg-primary: #0a0e1a;
  --bg-secondary: #111827;
  --bg-card: rgba(17, 24, 39, 0.7);
  --bg-card-hover: rgba(17, 24, 39, 0.85);
  --glass-border: rgba(99, 102, 241, 0.2);
  --glass-border-hover: rgba(99, 102, 241, 0.4);

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --accent-primary: #6366f1;
  --accent-secondary: #8b5cf6;
  --accent-tertiary: #06b6d4;
  --accent-glow: rgba(99, 102, 241, 0.3);

  --gradient-primary: linear-gradient(135deg, #6366f1, #8b5cf6);
  --gradient-hero: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #06b6d4 100%);
  --gradient-bg: linear-gradient(135deg, #0a0e1a 0%, #1a1040 25%, #0a0e1a 50%, #0d1f2d 75%, #0a0e1a 100%);

  --shadow-glow: 0 0 30px rgba(99, 102, 241, 0.15);
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-button: 0 4px 15px rgba(99, 102, 241, 0.4);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;

  --font-body: 'Inter', sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background: var(--gradient-bg);
  background-size: 400% 400%;
  animation: gradientShift 15s ease infinite;
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  position: relative;
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(99, 102, 241, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 20%, rgba(139, 92, 246, 0.06) 0%, transparent 50%),
    radial-gradient(ellipse at 50% 80%, rgba(6, 182, 212, 0.05) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

@keyframes gradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

/* ===== NAVBAR ===== */
.navbar-custom {
  background: rgba(10, 14, 26, 0.85) !important;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  padding: 0.75rem 0;
  z-index: 1000;
  transition: var(--transition-normal);
}

.navbar-custom .navbar-brand {
  font-weight: 700;
  font-size: 1.3rem;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 0.5px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.navbar-custom .navbar-brand i {
  -webkit-text-fill-color: var(--accent-primary);
  font-size: 1.4rem;
}

.navbar-custom .nav-link {
  color: var(--text-secondary) !important;
  font-weight: 500;
  padding: 0.5rem 1rem !important;
  border-radius: var(--radius-sm);
  transition: var(--transition-fast);
  position: relative;
}

.navbar-custom .nav-link:hover,
.navbar-custom .nav-link.active {
  color: var(--text-primary) !important;
  background: rgba(99, 102, 241, 0.1);
}

.navbar-custom .nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: var(--gradient-primary);
  border-radius: 1px;
}

.navbar-custom .dropdown-menu {
  background: rgba(17, 24, 39, 0.95);
  backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 0.5rem;
  margin-top: 0.5rem;
  box-shadow: var(--shadow-card);
}

.navbar-custom .dropdown-item {
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  padding: 0.5rem 1rem;
  transition: var(--transition-fast);
}

.navbar-custom .dropdown-item:hover {
  color: var(--text-primary);
  background: rgba(99, 102, 241, 0.15);
}

.navbar-toggler {
  border-color: var(--glass-border) !important;
}

.navbar-toggler-icon {
  filter: invert(0.7);
}

/* ===== MAIN CONTENT ===== */
.main-content {
  position: relative;
  z-index: 1;
  min-height: calc(100vh - 72px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem 1rem;
}

/* ===== GLASS CARD ===== */
.glass-card {
  background: var(--bg-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-xl);
  padding: 2.5rem;
  box-shadow: var(--shadow-card);
  transition: var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.glass-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(99, 102, 241, 0.5), transparent);
}

.glass-card:hover {
  border-color: var(--glass-border-hover);
  box-shadow: var(--shadow-glow), var(--shadow-card);
  transform: translateY(-2px);
}

/* ===== HERO SECTION ===== */
.hero-section {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero-icon {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.5rem;
  font-size: 2rem;
  color: white;
  box-shadow: var(--shadow-button);
  animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(99, 102, 241, 0.4); }
  50% { box-shadow: 0 0 0 15px rgba(99, 102, 241, 0); }
}

.hero-title {
  font-size: 2.5rem;
  font-weight: 800;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1rem;
  line-height: 1.2;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
  line-height: 1.6;
}

/* ===== FEATURE CARDS ===== */
.feature-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: 1rem;
}

.feature-card {
  background: rgba(17, 24, 39, 0.5);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  text-align: center;
  transition: var(--transition-normal);
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  display: block;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(99, 102, 241, 0.05), transparent);
  transition: var(--transition-slow);
}

.feature-card:hover::before {
  left: 100%;
}

.feature-card:hover {
  border-color: var(--glass-border-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
  color: inherit;
  text-decoration: none;
}

.feature-card-icon {
  width: 60px;
  height: 60px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1.25rem;
  font-size: 1.5rem;
  color: white;
}

.feature-card-icon.encrypt {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
}

.feature-card-icon.decrypt {
  background: linear-gradient(135deg, #06b6d4, #0ea5e9);
}

.feature-card-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.feature-card-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ===== PAGE CARD (encrypt/decrypt) ===== */
.page-card {
  max-width: 560px;
  width: 100%;
  margin: 0 auto;
}

.page-card-header {
  text-align: center;
  margin-bottom: 2rem;
}

.page-icon {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 1rem;
  font-size: 1.5rem;
  color: white;
  box-shadow: var(--shadow-button);
}

.page-icon.encrypt-icon {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
}

.page-icon.decrypt-icon {
  background: linear-gradient(135deg, #06b6d4, #0ea5e9);
}

.page-title {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.page-subtitle {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* ===== FILE UPLOAD AREA ===== */
.file-upload-area {
  border: 2px dashed var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  text-align: center;
  transition: var(--transition-normal);
  cursor: pointer;
  background: rgba(99, 102, 241, 0.03);
  margin-bottom: 1.5rem;
}

.file-upload-area:hover {
  border-color: var(--accent-primary);
  background: rgba(99, 102, 241, 0.08);
}

.file-upload-area i {
  font-size: 2.5rem;
  color: var(--accent-primary);
  margin-bottom: 0.75rem;
  display: block;
}

.file-upload-area p {
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

.file-upload-area .file-types {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.file-upload-area input[type="file"] {
  display: none;
}

.file-name-display {
  margin-top: 0.75rem;
  padding: 0.5rem 1rem;
  background: rgba(99, 102, 241, 0.1);
  border-radius: var(--radius-sm);
  color: var(--accent-primary);
  font-size: 0.85rem;
  display: none;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.file-name-display.active {
  display: flex;
}

/* ===== FORM ELEMENTS ===== */
.form-group {
  margin-bottom: 1.5rem;
}

.form-label-custom {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.form-input {
  width: 100%;
  padding: 0.85rem 1rem;
  background: rgba(17, 24, 39, 0.6);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 0.95rem;
  transition: var(--transition-normal);
  outline: none;
}

.form-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-glow);
  background: rgba(17, 24, 39, 0.8);
}

.form-input::placeholder {
  color: var(--text-muted);
}

/* ===== BUTTONS ===== */
.btn-gradient {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 2rem;
  background: var(--gradient-primary);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-normal);
  box-shadow: var(--shadow-button);
  width: 100%;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.btn-gradient:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

.btn-gradient:active {
  transform: translateY(0);
}

.btn-gradient.decrypt-btn {
  background: linear-gradient(135deg, #06b6d4, #0ea5e9);
  box-shadow: 0 4px 15px rgba(6, 182, 212, 0.4);
}

.btn-gradient.decrypt-btn:hover {
  box-shadow: 0 6px 20px rgba(6, 182, 212, 0.5);
}

/* ===== ALERT ===== */
.alert-custom {
  background: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.3);
  border-radius: var(--radius-md);
  color: #fca5a5;
  padding: 0.75rem 1rem;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  animation: slideIn 0.3s ease;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.alert-custom i {
  font-size: 1.1rem;
  color: #ef4444;
}

.alert-custom .btn-close {
  filter: invert(0.7);
  margin-left: auto;
}

/* ===== ABOUT PAGE ===== */
.about-section {
  max-width: 800px;
  width: 100%;
  margin: 0 auto;
}

.about-header {
  text-align: center;
  margin-bottom: 2rem;
}

.about-title {
  font-size: 2rem;
  font-weight: 800;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.about-subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Custom Accordion */
.accordion-custom .accordion-item {
  background: rgba(17, 24, 39, 0.5);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md) !important;
  margin-bottom: 0.75rem;
  overflow: hidden;
}

.accordion-custom .accordion-button {
  background: transparent;
  color: var(--text-primary);
  font-weight: 600;
  font-size: 1rem;
  padding: 1.25rem 1.5rem;
  border: none;
  box-shadow: none !important;
  transition: var(--transition-normal);
}

.accordion-custom .accordion-button:not(.collapsed) {
  background: rgba(99, 102, 241, 0.08);
  color: var(--accent-primary);
}

.accordion-custom .accordion-button::after {
  filter: invert(0.6) sepia(1) hue-rotate(200deg);
}

.accordion-custom .accordion-body {
  background: transparent;
  color: var(--text-secondary);
  padding: 0 1.5rem 1.5rem;
  line-height: 1.7;
  font-size: 0.95rem;
}

.accordion-custom .accordion-body strong {
  color: var(--text-primary);
}

/* ===== FOOTER ===== */
.footer-custom {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 1.5rem;
  border-top: 1px solid var(--glass-border);
  color: var(--text-muted);
  font-size: 0.85rem;
  background: rgba(10, 14, 26, 0.5);
  backdrop-filter: blur(10px);
}

.footer-custom a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: var(--transition-fast);
}

.footer-custom a:hover {
  color: var(--accent-secondary);
}

/* ===== ANIMATIONS ===== */
.fade-in {
  animation: fadeIn 0.6s ease forwards;
}

.fade-in-up {
  animation: fadeInUp 0.6s ease forwards;
}

.fade-in-up-delay {
  animation: fadeInUp 0.6s ease 0.15s forwards;
  opacity: 0;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .hero-title {
    font-size: 1.75rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .glass-card {
    padding: 1.75rem;
  }

  .feature-cards {
    grid-template-columns: 1fr;
  }

  .main-content {
    padding: 1.5rem 1rem;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.5rem;
  }

  .glass-card {
    padding: 1.25rem;
    border-radius: var(--radius-lg);
  }
}