:root {
  --bg: #0b1020;
  --panel: rgba(255, 255, 255, 0.05);
  --panel-hover: rgba(255, 255, 255, 0.08);
  --border: rgba(255, 255, 255, 0.1);
  --text-main: #e5e7eb;
  --text-muted: #9ca3af;
  --accent: #38bdf8;       /* Sky Blue */
  --accent-hover: #0ea5e9;
  --danger: #ef4444;       /* Red */
  --font-stack: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
}

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

body {
  background-color: var(--bg);
  background-image: 
    radial-gradient(at 0% 0%, rgba(56, 189, 248, 0.15) 0px, transparent 50%),
    radial-gradient(at 100% 100%, rgba(167, 139, 250, 0.15) 0px, transparent 50%);
  color: var(--text-main);
  font-family: var(--font-stack);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

main {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1 {
  margin-bottom: 24px;
  font-weight: 800;
  letter-spacing: -0.5px;
  background: linear-gradient(to right, #38bdf8, #a78bfa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* --- Card Container --- */
.todo-app {
  background-color: var(--panel);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  width: min(480px, 92vw);
  height: 600px;
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 24px;
  position: relative;
  display: flex;
  flex-direction: column;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
  overflow: hidden;
}

/* --- Buttons --- */
.btn {
  cursor: pointer;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s ease;
  padding: 10px 20px;
}

.primary-btn {
  background-color: var(--accent);
  color: #0f172a;
  width: 100%;
}

.primary-btn:hover {
  background-color: var(--accent-hover);
  transform: translateY(-1px);
}

.secondary-btn {
  background-color: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.secondary-btn:hover {
  color: var(--text-main);
  border-color: var(--text-main);
}

.danger-btn {
  background-color: rgba(239, 68, 68, 0.15);
  color: var(--danger);
  border: 1px solid rgba(239, 68, 68, 0.3);
}

.danger-btn:hover {
  background-color: rgba(239, 68, 68, 0.25);
}

/* --- Modal Form --- */
.task-form {
  position: absolute;
  inset: 0;
  background-color: #0f172a; /* Solid dark color to cover list */
  padding: 30px;
  display: flex;
  flex-direction: column;
  z-index: 10;
  animation: slideUp 0.3s ease-out;
}

@keyframes slideUp {
  from { transform: translateY(100%); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

.task-form-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
}

.form-title {
  font-size: 1.5rem;
  margin: 0;
}

.close-task-form-btn {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-muted);
  padding: 4px;
}

.close-task-form-btn:hover {
  color: var(--danger);
}

.task-form-body {
  flex: 1;
}

.task-form-label {
  display: block;
  margin-bottom: 8px;
  color: var(--accent);
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.form-control {
  width: 100%;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border);
  color: white;
  padding: 12px;
  border-radius: 8px;
  margin-bottom: 24px;
  font-family: inherit;
  font-size: 1rem;
}

.form-control:focus {
  outline: none;
  border-color: var(--accent);
  background: rgba(255, 255, 255, 0.1);
}

/* --- Dialog --- */
dialog {
  background: #1e293b;
  color: white;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  margin: auto;
}

dialog::backdrop {
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
}

/* --- Task List --- */
#tasks-container {
  flex: 1;
  overflow-y: auto;
  margin-top: 20px;
  padding-right: 5px;
}

/* Custom Scrollbar */
#tasks-container::-webkit-scrollbar {
  width: 6px;
}
#tasks-container::-webkit-scrollbar-thumb {
  background-color: var(--border);
  border-radius: 10px;
}

.task {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
  transition: background 0.2s;
}

.task:hover {
  background: var(--panel-hover);
  border-color: rgba(56, 189, 248, 0.3);
}

.task h3 {
  font-size: 1.1rem;
  margin-bottom: 4px;
}

.task-date {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 12px;
  display: block;
}

.task-desc {
  font-size: 0.95rem;
  line-height: 1.4;
  margin-bottom: 16px;
  color: #d1d5db;
}

.task-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
}

.task-btn {
  padding: 6px 12px;
  font-size: 0.8rem;
}

.hidden {
  display: none;
}