* Reset and Box Sizing */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* CSS Variables - Light Mode */
:root {
  --bg-gradient-start: #667eea;
  --bg-gradient-end: #4facfe;
  --card-bg: #ffffff;
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-tertiary: #9ca3af;
  --border-color: #e5e7eb;
  --input-border: #e5e7eb;
  --input-focus: #6366f1;
  --item-bg: #f9fafb;
  --completed-bg: #d1fae5;
  --btn-primary: #6366f1;
  --btn-secondary: #8b5cf6;
  --edit-btn-bg: #dbeafe;
  --edit-btn-color: #2563eb;
  --delete-btn-bg: #fecaca;
  --delete-btn-color: #dc2626;
  --modal-overlay: rgba(0,0,0,0.5);
  --shadow: rgba(0,0,0,0.2);
}

/* CSS Variables - Dark Mode */
body.dark-mode {
  --bg-gradient-start: #1e293b;
  --bg-gradient-end: #0f172a;
  --card-bg: #1e293b;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-tertiary: #94a3b8;
  --border-color: #334155;
  --input-border: #334155;
  --input-focus: #818cf8;
  --item-bg: #0f172a;
  --completed-bg: #064e3b;
  --btn-primary: #6366f1;
  --btn-secondary: #8b5cf6;
  --edit-btn-bg: #1e3a8a;
  --edit-btn-color: #60a5fa;
  --delete-btn-bg: #7f1d1d;
  --delete-btn-color: #f87171;
  --modal-overlay: rgba(0,0,0,0.8);
  --shadow: rgba(0,0,0,0.5);
}

/* Body and Container */
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
  min-height: 100vh;
  padding: 20px;
  padding-bottom: 80px;
  transition: background 0.3s ease;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

/* Header */
header {
  text-align: center;
  color: white;
  margin-bottom: 30px;
  position: relative;
}

h1 {
  font-size: 32px;
  margin-bottom: 5px;
}

.tagline {
  opacity: 0.9;
  font-size: 14px;
}

.dark-mode-toggle {
  position: absolute;
  top: 0;
  right: 0;
  background: rgba(255,255,255,0.2);
  border: none;
  color: white;
  padding: 8px 16px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 20px;
  transition: background 0.3s;
}

.dark-mode-toggle:hover {
  background: rgba(255,255,255,0.3);
}

/* Authentication */
.auth-container {
  max-width: 400px;
  margin: 100px auto;
  text-align: center;
}

.auth-card {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 40px;
  box-shadow: 0 10px 30px var(--shadow);
}

.auth-title {
  font-size: 24px;
  margin-bottom: 10px;
  color: var(--text-primary);
}

.auth-subtitle {
  color: var(--text-secondary);
  margin-bottom: 30px;
}

/* User Info */
.user-info {
  display: flex;
  align-items: center;
  gap: 15px;
  background: rgba(255,255,255,0.2);
  padding: 12px 16px;
  border-radius: 8px;
  color: white;
  margin-bottom: 20px;
}

.user-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 2px solid white;
}

.user-details {
  flex: 1;
  text-align: left;
}

.user-name {
  font-weight: 600;
  font-size: 14px;
}

.user-email {
  font-size: 12px;
  opacity: 0.9;
}

.sign-out-btn {
  background: rgba(255,255,255,0.2);
  color: white;
  border: 1px solid rgba(255,255,255,0.3);
  padding: 8px 16px;
  border-radius: 6px;
  font-size: 14px;
  cursor: pointer;
}

/* Cards */
.card {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: 0 10px 30px var(--shadow);
}

.section-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 15px;
  color: var(--text-primary);
}

/* Collapsible Forms */
.collapsible-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  margin-bottom: 0;
}

.collapsible-header:hover {
  opacity: 0.8;
}

.collapsible-header .section-title {
  margin-bottom: 0;
}

.collapse-icon {
  font-size: 14px;
  color: var(--text-secondary);
  transition: transform 0.3s ease;
  font-weight: bold;
}

.collapse-icon.collapsed {
  transform: rotate(-90deg);
}

.collapsible-content {
  max-height: 500px;
  overflow: hidden;
  transition: max-height 0.3s ease, opacity 0.3s ease, margin-top 0.3s ease;
  opacity: 1;
  margin-top: 15px;
}

.collapsible-content.collapsed {
  max-height: 0;
  opacity: 0;
  margin-top: 0;
}

/* Forms */
.add-habit-form, .add-task-form, .add-blog-form, .add-bookmark-form {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 20px;
}

input[type="text"], input[type="date"], input[type="url"], textarea, select {
  padding: 12px;
  border: 2px solid var(--input-border);
  border-radius: 8px;
  font-size: 16px;
  outline: none;
  transition: border-color 0.3s;
  font-family: inherit;
  background: var(--card-bg);
  color: var(--text-primary);
}

input[type="text"]:focus, input[type="date"]:focus, input[type="url"]:focus, textarea:focus, select:focus {
  border-color: var(--input-focus);
}

textarea {
  resize: vertical;
  min-height: 60px;
}

.char-counter {
  font-size: 12px;
  color: var(--text-secondary);
  text-align: right;
  margin-top: -5px;
}

.char-counter.warning {
  color: #dc2626;
}

.form-row {
  display: flex;
  gap: 10px;
}

/* Buttons */
.btn {
  padding: 12px 24px;
  background: var(--btn-primary);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.btn:active {
  background: #4f46e5;
}

.btn-google {
  background: white;
  color: #1f2937;
  border: 2px solid var(--border-color);
  width: 100%;
  justify-content: center;
}

.btn-google:hover {
  background: #f9fafb;
}

.btn-cancel {
  background: var(--item-bg);
  color: var(--text-primary);
}

/* Lists */
.habit-list, .task-list, .blog-list, .bookmark-list {
  list-style: none;
}

.habit-item, .task-item, .bookmark-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 15px;
  background: var(--item-bg);
  border-radius: 8px;
  margin-bottom: 10px;
  transition: background 0.3s;
}

.habit-item.completed, .task-item.completed {
  background: var(--completed-bg);
}

.task-item.completed .task-name {
  text-decoration: line-through;
  opacity: 0.6;
}

.habit-info, .task-info, .bookmark-info {
  flex: 1;
  cursor: pointer;
}

.habit-name, .task-name, .bookmark-name {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.bookmark-name {
  text-decoration: none;
  color: var(--btn-primary);
  display: inline-block;
}

.bookmark-name:hover {
  text-decoration: underline;
}

.bookmark-type {
  font-size: 12px;
  color: var(--text-secondary);
  margin-top: 4px;
  display: inline-block;
  padding: 2px 8px;
  background: var(--completed-bg);
  border-radius: 4px;
}

.bookmark-url {
  font-size: 11px;
  color: var(--text-tertiary);
  margin-top: 3px;
  word-break: break-all;
}

.task-description {
  font-size: 14px;
  color: var(--text-secondary);
  margin-top: 5px;
}

.task-original-date {
  font-size: 11px;
  color: var(--text-tertiary);
  margin-top: 3px;
  font-style: italic;
}

.habit-streak {
  font-size: 12px;
  color: var(--text-secondary);
}

.habit-actions, .task-actions, .bookmark-actions {
  display: flex;
  gap: 8px;
}

.checkbox-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 2px solid var(--btn-primary);
  background: var(--card-bg);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  transition: all 0.3s;
}

.checkbox-btn.checked {
  background: var(--btn-primary);
  color: white;
}

.edit-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: none;
  background: var(--edit-btn-bg);
  color: var(--edit-btn-color);
  cursor: pointer;
  font-size: 18px;
}

.delete-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: none;
  background: var(--delete-btn-bg);
  color: var(--delete-btn-color);
  cursor: pointer;
  font-size: 18px;
}

/* Blog Posts */
.blog-post {
  background: var(--item-bg);
  border-radius: 8px;
  padding: 15px;
  margin-bottom: 15px;
  border-left: 4px solid var(--btn-primary);
}

.blog-content {
  color: var(--text-primary);
  line-height: 1.6;
  margin-bottom: 10px;
}

.blog-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 12px;
  color: var(--text-secondary);
}

.blog-location {
  display: flex;
  align-items: center;
  gap: 5px;
}

.blog-actions {
  display: flex;
  gap: 8px;
}

.blog-edit-btn, .blog-delete-btn {
  background: none;
  border: none;
  color: var(--edit-btn-color);
  cursor: pointer;
  padding: 4px 8px;
  font-size: 12px;
}

.blog-delete-btn {
  color: var(--delete-btn-color);
}

/* Filters */
.date-filter-container {
  display: flex;
  gap: 10px;
  align-items: center;
  margin-bottom: 15px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 8px 16px;
  background: var(--item-bg);
  color: var(--text-primary);
  border: 2px solid var(--border-color);
  border-radius: 8px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  transition: all 0.3s;
}

.filter-btn.active {
  background: var(--btn-primary);
  color: white;
  border-color: var(--btn-primary);
}

/* Tabs */
.tabs {
  display: flex;
  gap: 10px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.tab {
  flex: 1;
  min-width: 80px;
  padding: 12px;
  background: rgba(255,255,255,0.2);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s;
}

.tab.active {
  background: white;
  color: var(--btn-primary);
}

body.dark-mode .tab.active {
  background: var(--card-bg);
  color: var(--btn-primary);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

/* News Grid */
.news-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

@media (min-width: 768px) {
  .news-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.news-item {
  padding: 15px 0;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  gap: 15px;
  align-items: flex-start;
}

.news-item:last-child {
  border-bottom: none;
}

.news-image {
  width: 120px;
  height: 80px;
  object-fit: cover;
  border-radius: 8px;
  flex-shrink: 0;
  background: var(--item-bg);
}

.news-content {
  flex: 1;
  min-width: 0;
}

.news-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 5px;
  line-height: 1.4;
}

.news-link {
  color: var(--btn-primary);
  text-decoration: none;
  font-size: 14px;
}

.news-date {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 5px;
}

.loading {
  text-align: center;
  color: var(--text-secondary);
  padding: 20px;
}

.empty-state {
  text-align: center;
  color: var(--text-tertiary);
  padding: 30px 0;
}

.news-error {
  color: #ef4444;
  font-style: italic;
  padding: 20px;
  text-align: center;
  font-size: 14px;
}

/* Modals */
.modal {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: var(--modal-overlay);
}

.modal.show {
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-content {
  background: var(--card-bg);
  padding: 30px;
  border-radius: 16px;
  max-width: 500px;
  width: 90%;
  box-shadow: 0 20px 60px var(--shadow);
}

.modal-title {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 20px;
  color: var(--text-primary);
}

.modal-buttons {
  display: flex;
  gap: 10px;
  margin-top: 20px;
  justify-content: flex-end;
}

.hidden {
  display: none !important;
}

/* Habit Calendar Modal */
.habit-calendar-modal {
  display: none;
  position: fixed;
  z-index: 1001;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: var(--modal-overlay);
}

.habit-calendar-modal.show {
  display: flex;
  align-items: center;
  justify-content: center;
  animation: fadeIn 0.3s ease;
}

.habit-calendar-content {
  background: var(--card-bg);
  padding: 30px;
  border-radius: 16px;
  max-width: 500px;
  width: 90%;
  box-shadow: 0 20px 60px var(--shadow);
  animation: slideUp 0.3s ease;
}

.habit-calendar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.habit-calendar-title {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
}

.calendar-nav {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: center;
  margin-bottom: 15px;
}

.calendar-nav-btn {
  background: var(--item-bg);
  border: none;
  color: var(--text-primary);
  padding: 8px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  transition: background 0.3s;
}

.calendar-nav-btn:hover {
  background: var(--btn-primary);
  color: white;
}

.calendar-month-year {
  font-weight: 600;
  color: var(--text-primary);
  min-width: 140px;
  text-align: center;
}

.calendar-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 8px;
  margin-top: 15px;
}

.calendar-day-header {
  text-align: center;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 8px 0;
}

.calendar-day {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  font-size: 14px;
  color: var(--text-primary);
  background: var(--item-bg);
  cursor: default;
  position: relative;
  transition: all 0.3s ease;
}

.calendar-day.empty {
  background: transparent;
}

.calendar-day.completed {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  color: white;
  font-weight: 600;
  animation: popIn 0.3s ease;
  box-shadow: 0 4px 12px rgba(16, 185, 129, 0.4);
}

.calendar-day.today {
  border: 2px solid var(--btn-primary);
  font-weight: 600;
}

.calendar-day.completed.today {
  border: 2px solid #fff;
}

.calendar-stats {
  margin-top: 20px;
  padding: 15px;
  background: var(--item-bg);
  border-radius: 8px;
  display: flex;
  justify-content: space-around;
  gap: 15px;
}

.calendar-stat {
  text-align: center;
}

.calendar-stat-value {
  font-size: 24px;
  font-weight: 700;
  color: var(--btn-primary);
}

.calendar-stat-label {
  font-size: 12px;
  color: var(--text-secondary);
  margin-top: 4px;
}

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

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

@keyframes popIn {
  0% {
    transform: scale(0.8);
    opacity: 0;
  }
  50% {
    transform: scale(1.1);
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}