:root {
  --bg-dark: #0f172a;
  --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
  --surface-glass: rgba(255, 255, 255, 0.03);
  --surface-border: rgba(255, 255, 255, 0.08);
  --text-main: #f8fafc;
  --text-muted: #64748b;
  --danger: #ef4444;

  /* Radii & Shadows */
  --radius-xl: 24px;
  --radius-lg: 16px;
  --radius-pill: 9999px;
  --shadow-glass: 0 8px 32px 0 rgba(0, 0, 0, 0.3);
}

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

body {
  font-family:
    "Inter",
    -apple-system,
    sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-main);
  display: grid;
  place-items: center;
  min-height: 100vh;
  padding: 1rem;
  overflow: hidden;
  position: relative;
}

/* --- Splash Screen --- */
.splash-screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: var(--bg-dark);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition:
    opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1),
    visibility 0.6s;
}

/* trigger this class with JavaScript when the app is ready */
.splash-screen.hidden {
  opacity: 0;
  visibility: hidden;
}

/*  gradient spinner */
.loader {
  margin-top: 2.5rem;
  width: 36px;
  height: 36px;
  border: 4px solid rgba(255, 255, 255, 0.05);
  border-left-color: #a855f7;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* Ambient Background Glow */
.bg-shape {
  position: absolute;
  width: 50vw;
  height: 50vw;
  background: var(--accent-gradient);
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.15;
  top: -10%;
  left: -10%;
  z-index: -1;
  animation: pulse 10s ease-in-out infinite alternate;
}

@keyframes pulse {
  0% {
    transform: scale(1) translate(0, 0);
  }
  100% {
    transform: scale(1.1) translate(5%, 5%);
  }
}

.app-container {
  background: var(--surface-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  width: 100%;
  max-width: 480px;
  padding: 2.5rem;
  border-radius: var(--radius-xl);
  border: 1px solid var(--surface-border);
  box-shadow: var(--shadow-glass);
  z-index: 1;
}

header h1 {
  font-size: 1.75rem;
  font-weight: 600;
  margin-bottom: 2rem;
  text-align: center;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.02em;
}

/* Integrated Input Group */
.input-group {
  display: flex;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-pill);
  padding: 0.35rem;
  margin-bottom: 2.5rem;
  transition:
    border-color 0.3s ease,
    box-shadow 0.3s ease;
}

.input-group:focus-within {
  border-color: #6366f1;
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

#todo-input {
  flex: 1;
  background: transparent;
  border: none;
  padding: 0.75rem 1.25rem;
  color: var(--text-main);
  font-size: 1rem;
  outline: none;
  font-family: inherit;
}

#todo-input::placeholder {
  color: var(--text-muted);
}

/* Motivational Note */
.motivational-note-container {
  background: rgba(255, 255, 255, 0.03);
  border-left: 3px solid #a855f7;
  padding: 0.85rem 1.25rem;
  border-radius: var(--radius-lg);
  margin-bottom: 2rem;
  transition: all 0.3s ease;
  position: relative;
}

.motivational-note-container:hover,
.motivational-note-container:focus-within {
  background: rgba(255, 255, 255, 0.06);
  transform: translateX(4px);
}

#motivational-note {
  font-size: 0.95rem;
  color: var(--text-muted);
  font-style: italic;
  outline: none;
  line-height: 1.5;
  transition: color 0.3s ease;
}

#motivational-note:empty::before {
  content: "Write a note to keep yourself going...";
  color: rgba(100, 116, 139, 0.5); /* Faded muted text */
}

#motivational-note:focus {
  color: var(--text-main);
  font-style: normal;
}

.btn-primary {
  background: var(--accent-gradient);
  color: white;
  border: none;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  cursor: pointer;
  transition:
    transform 0.2s ease,
    box-shadow 0.2s ease;
}

.btn-primary:hover {
  transform: scale(1.05);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.btn-primary:active {
  transform: scale(0.95);
}

/* List Styling */
.todo-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.todo-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid transparent;
  border-radius: var(--radius-lg);
  transition: all 0.3s ease;
}

.todo-item:hover {
  background: rgba(255, 255, 255, 0.04);
  border-color: var(--surface-border);
  transform: translateY(-2px);
}

.todo-content {
  display: flex;
  align-items: center;
  gap: 1rem;
  cursor: pointer;
  font-weight: 400;
  color: var(--text-main);
  transition: color 0.3s ease;
  width: 100%; /* Ensures the clickable area spans across */
}

/* Custom Checkbox mimicking */
.todo-content::before {
  content: "";
  display: inline-block;
  min-width: 20px;
  height: 20px;
  border: 2px solid var(--text-muted);
  border-radius: 6px;
  transition: all 0.2s ease;
}

/* Completed State */
.todo-item.completed .todo-content {
  color: var(--text-muted);
  text-decoration: line-through;
}

.todo-item.completed .todo-content::before {
  background: var(--accent-gradient);
  border-color: transparent;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='20 6 9 17 4 12'%3E%3C/polyline%3E%3C/svg%3E");
  background-size: 12px;
  background-position: center;
  background-repeat: no-repeat;
}

.delete-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1.5rem;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  transition: all 0.2s ease;
  opacity: 0;
  margin-left: 0.5rem;
}

.todo-item:hover .delete-btn {
  opacity: 1;
}

.delete-btn:hover {
  color: var(--danger);
  background: rgba(239, 68, 68, 0.1);
}

/* --- Mobile Responsiveness --- */
@media (max-width: 600px) {
  /* Reduce container padding to maximize screen space */
  .app-container {
    padding: 1.5rem;
    border-radius: var(--radius-lg);
  }

  /* Slightly scale down the header */
  header h1 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
  }

  /* Adjust the motivational note padding */
  .motivational-note-container {
    padding: 0.75rem 1rem;
    margin-bottom: 1.5rem;
  }

  #motivational-note {
    font-size: 0.9rem;
  }

  /* CRITICAL: Make delete buttons always visible on mobile */
  /* Touch devices don't have hover, so users need to see the button */
  .delete-btn {
    opacity: 1;
    background: rgba(239, 68, 68, 0.05); /* Very subtle red background */
  }

  /* Make the ambient background shape larger for portrait screens */
  .bg-shape {
    width: 80vw;
    height: 80vw;
    top: -5%;
    left: -15%;
  }

  /* Scale down the splash screen logo slightly */
  .splash-screen svg {
    width: 60px;
    height: 60px;
  }
}