:root {
  --bg-gradient-1: #0f172a;
  --bg-gradient-2: #1e1b4b;
  --glass-bg: rgba(255, 255, 255, 0.05);
  --glass-border: rgba(255, 255, 255, 0.1);
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --accent: #818cf8;
  --accent-hover: #6366f1;
  --danger: #fb7185;
  --danger-hover: #e11d48;
  --item-bg: rgba(255, 255, 255, 0.03);
  --item-hover: rgba(255, 255, 255, 0.08);
}

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

body {
  font-family: 'Outfit', sans-serif;
  background: var(--bg-gradient-1);
  color: var(--text-main);
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  position: relative;
}

.background-animation {
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 50% 50%, rgba(99, 102, 241, 0.15), transparent 60%),
              radial-gradient(circle at 80% 20%, rgba(139, 92, 246, 0.15), transparent 50%);
  animation: rotateBg 20s linear infinite;
  z-index: -1;
}

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

.container {
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  padding: 30px;
  width: 100%;
  max-width: 400px;
  border-radius: 24px;
  box-shadow: 0 25px 50px -12px rgba(0,0,0,0.5);
  display: flex;
  flex-direction: column;
  max-height: 85vh;
}

.header {
  margin-bottom: 25px;
}

h2 {
  font-size: 28px;
  font-weight: 600;
  letter-spacing: -0.5px;
}

.subtitle {
  color: var(--text-muted);
  font-size: 14px;
  margin-top: 4px;
}

.input-area {
  display: flex;
  gap: 12px;
  margin-bottom: 25px;
}

input {
  flex: 1;
  padding: 14px 18px;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  color: var(--text-main);
  font-family: inherit;
  font-size: 15px;
  outline: none;
  transition: all 0.3s ease;
}

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

input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(129, 140, 248, 0.15);
}

button#addBtn {
  width: 50px;
  height: 50px;
  border: none;
  background: var(--accent);
  color: white;
  border-radius: 14px;
  cursor: pointer;
  font-size: 18px;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: all 0.3s ease;
  box-shadow: 0 4px 12px rgba(129, 140, 248, 0.3);
}

button#addBtn:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(129, 140, 248, 0.4);
}

button#addBtn:active {
  transform: translateY(0);
}

ul {
  list-style: none;
  overflow-y: auto;
  padding-right: 5px;
}

/* Custom Scrollbar */
ul::-webkit-scrollbar {
  width: 6px;
}
ul::-webkit-scrollbar-track {
  background: transparent;
}
ul::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.1);
  border-radius: 10px;
}
ul::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.2);
}

li {
  padding: 16px;
  margin-bottom: 12px;
  background: var(--item-bg);
  border: 1px solid var(--glass-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-radius: 14px;
  transition: all 0.3s ease;
  animation: slideIn 0.3s ease-out forwards;
}

@keyframes slideIn {
  from { opacity: 0; transform: translateY(15px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideOut {
  from { opacity: 1; transform: translateX(0); }
  to { opacity: 0; transform: translateX(30px); }
}

li:hover {
  background: var(--item-hover);
  transform: translateX(4px);
}

.task-content {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 1;
  word-break: break-word;
  cursor: pointer;
}

.checkbox {
  width: 22px;
  height: 22px;
  border-radius: 6px;
  border: 2px solid var(--text-muted);
  display: flex;
  justify-content: center;
  align-items: center;
  transition: all 0.2s;
  color: transparent;
  font-size: 12px;
}

li.completed .checkbox {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}

li.completed .task-text {
  text-decoration: line-through;
  color: var(--text-muted);
}

.task-text {
  font-size: 15px;
  transition: color 0.3s;
}

.delete-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 16px;
  cursor: pointer;
  padding: 8px;
  border-radius: 8px;
  transition: all 0.2s;
  opacity: 0.5;
}

li:hover .delete-btn {
  opacity: 1;
}

.delete-btn:hover {
  color: var(--danger);
  background: rgba(251, 113, 133, 0.1);
  opacity: 1;
}