:root {
  --bg-color: #ffffff;
  --bg-secondary: #f7f7f7;
  --text-main: #222222;
  --text-secondary: #717171;
  --border-color: #ebebeb;
  --border-dark: #b0b0b0;
  --black: #000000;
  --white: #ffffff;
  --hover-bg: #f7f7f7;
  --radius-sm: 8px;
  --radius-md: 16px;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --nav-width: 80px;
}

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

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  font-family: var(--font-sans);
  line-height: 1.5;
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

#app-layout {
  display: flex;
  height: 100dvh;
  width: 100%;
}

/* Sidebar Nav - Desktop (Left Side) */
#nav {
  width: var(--nav-width);
  background-color: var(--bg-color);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 2rem 0;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
}

#nav.hidden {
  display: none !important;
}

/* Nav Link Hover */
.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  text-decoration: none;
  margin: 1rem 0;
  font-size: 0.75rem;
  font-weight: 500;
  transition: color 0.2s ease;
  gap: 0.1rem;
}

.nav-item:hover {
  color: var(--text-main);
}

.nav-item.active {
  color: var(--black);
}

.nav-item svg {
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  box-sizing: content-box;
  transition: background-color 0.2s ease;
}

.nav-item:hover svg, .nav-item.active svg {
  background-color: var(--hover-bg);
}

.mt-auto {
  margin-top: auto;
}

/* Main Content Area */
#app-content {
  flex: 1;
  padding: 3rem;
  display: flex;
  flex-direction: column;
}

.page-container {
  max-width: 650px;
  width: 100%;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
}

#mobile-header {
  display: none;
  margin-bottom: 2rem;
}

#mobile-header h1 {
  border-bottom: none;
  margin-bottom: 0;
  padding-bottom: 0;
}

h1, h2, h3 {
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 1.5rem;
}

h2 {
  font-size: 2rem;
  border-bottom: none;
  padding-bottom: 0;
}

h3 {
  font-size: 1.25rem;
}

/* Forms & Inputs */
.form-group {
  display: flex;
  flex-direction: column;
  max-width: 480px;
}

label {
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-main);
}

input:not([type="checkbox"]), select, textarea {
  font-family: var(--font-sans);
  background: var(--bg-color);
  border: 1px solid var(--border-dark);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  padding: 0.75rem 1rem;
  font-size: 1rem;
  margin-bottom: 1.5rem;
  transition: border-color 0.2s ease;
}

input:not([type="checkbox"]):focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--black);
  box-shadow: 0 0 0 1px var(--black);
}

textarea {
  resize: vertical;
}

/* Buttons */
button {
  cursor: pointer;
  background-color: var(--black);
  color: var(--white);
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-sans);
  transition: transform 0.1s ease, background-color 0.2s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

button:hover {
  background-color: #222222;
}

button:active {
  transform: scale(0.98);
}

button.secondary {
  background-color: transparent;
  color: var(--text-main);
  border: 1px solid var(--border-dark);
}

button.secondary:hover {
  background-color: var(--bg-secondary);
  border-color: var(--text-main);
}

button.danger {
  background-color: #dc2626;
  color: white;
}

button.danger:hover {
  background-color: #b91c1c;
}

/* Icon Buttons */
button.icon-btn {
  padding: 0.6rem;
  background: var(--bg-secondary);
  border: none;
  color: var(--text-main);
  border-radius: 50%;
}

button.icon-btn:hover {
  background: #ebebeb;
}

button.icon-btn.danger {
  color: #dc2626;
  background: #fee2e2;
}

button.icon-btn.danger:hover {
  background: #fca5a5;
  color: #991b1b;
}

/* Dense Tasks */
.task-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0;
  border-top: 1px solid var(--border-color);
}

.task-item {
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0.5rem;
  background-color: transparent;
  display: flex;
  flex-direction: row;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  transition: background-color 0.2s ease;
}

.task-item:hover {
  background-color: var(--hover-bg);
}

.task-item-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  cursor: pointer;
}

.task-item-header {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.task-item.completed {
  opacity: 0.6;
}

.task-item.completed strong {
  text-decoration: line-through;
}

.task-meta {
  font-size: 0.8rem;
  color: var(--text-secondary);
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.task-actions {
  display: flex;
  gap: 0.25rem;
  flex-shrink: 0;
}

.hidden {
  display: none !important;
}

.badge {
  display: inline-block;
  padding: 0.25rem 0.6rem;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--bg-secondary);
  color: var(--text-main);
  border-radius: var(--radius-sm);
  vertical-align: middle;
}

/* Responsive Desktop vs Mobile */
@media (min-width: 768px) {
  #app-content {
    margin-left: var(--nav-width); 
  }
}

@media (max-width: 767px) {
  #app-layout {
    flex-direction: column;
  }

  #app-content {
    padding: 1rem;
    margin-left: 0;
  }

  /* Nav shifts to bottom bar */
  #nav {
    flex-direction: row;
    width: 100%;
    height: 75px;
    top: auto;
    bottom: 0;
    border-right: none;
    border-top: 1px solid var(--border-color);
    justify-content: space-around;
    padding: 0;
  }
  
  .nav-item {
    padding: 0.5rem 1rem;
    margin: 0;
  }
}