/* ========== Reset & Base ========== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Neumorphism Palette — soft, monochromatic */
  --bg: #eaeaea;
  --bg-light: #f5f5f5;
  --card-bg: #ececec;
  --accent: #6c5ce7;
  --accent-light: #a29bfe;
  --text: #2d3436;
  --text-muted: #999999;
  --text-light: #b0b0b0;
  --success: #00b894;
  --danger: #e17055;
  --radius: 16px;

  /* Neumorphism shadows */
  --shadow-out: 8px 8px 16px rgba(0,0,0,0.08),
                -8px -8px 16px rgba(255,255,255,0.9);
  --shadow-out-sm: 4px 4px 8px rgba(0,0,0,0.06),
                   -4px -4px 8px rgba(255,255,255,0.85);
  --shadow-in: inset 3px 3px 7px rgba(0,0,0,0.06),
               inset -3px -3px 7px rgba(255,255,255,0.85);
  --shadow-in-strong: inset 4px 4px 10px rgba(0,0,0,0.1),
                      inset -4px -4px 10px rgba(255,255,255,0.9);

  --font-sans: 'Inter', 'Helvetica Neue', Arial, sans-serif;
  --card-font-size: 22px;
  --transition: 0.2s ease;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ========== Material Symbols ========== */
.material-symbols-outlined {
  font-variation-settings: 'FILL' 0, 'wght' 300, 'GRAD' 0, 'opsz' 24;
  vertical-align: middle;
  line-height: 1;
}

/* ========== Header ========== */
.header {
  background: var(--card-bg);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-out-sm);
}

.header-inner {
  max-width: 100%;
  margin: 0 auto;
  padding: 16px 40px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.header-left, .header-center, .header-right {
  display: flex;
  align-items: center;
  gap: 16px;
}
.header-left { flex: 0 0 auto; }
.header-center { flex: 1; justify-content: center; }
.header-right { flex: 0 0 auto; }

.logo {
  font-family: var(--font-sans);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text);
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 8px;
}
.logo-icon { font-size: 1.3rem; color: var(--accent); }

/* Date nav */
.date-nav { display: flex; align-items: center; gap: 6px; }

.date-btn {
  background: var(--card-bg);
  border: none;
  border-radius: var(--radius);
  padding: 8px 14px;
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: var(--text);
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-out-sm);
}
.date-btn:hover { box-shadow: var(--shadow-in); color: var(--accent); }
.date-btn:active { box-shadow: var(--shadow-in-strong); }

.today-btn {
  background: var(--accent);
  color: white;
  font-weight: 600;
  font-size: 0.8rem;
  box-shadow: 4px 4px 8px rgba(108,92,231,0.25),
              -4px -4px 8px rgba(255,255,255,0.8);
}
.today-btn:hover { background: var(--accent-light); box-shadow: var(--shadow-in); }

.date-display { display: flex; align-items: center; gap: 8px; }

#datePicker {
  background: var(--card-bg);
  border: none;
  border-radius: var(--radius);
  padding: 8px 12px;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: var(--text);
  cursor: pointer;
  box-shadow: var(--shadow-in);
}

#dateLabel {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}

/* Font size control */
.font-size-control {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 6px 14px;
  box-shadow: var(--shadow-out-sm);
}

.fs-icon { font-size: 1rem; color: var(--text-muted); }

#fontSizeSlider {
  width: 72px;
  height: 6px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--bg);
  border-radius: 3px;
  outline: none;
  cursor: pointer;
  box-shadow: var(--shadow-in);
}
#fontSizeSlider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: none;
  box-shadow: var(--shadow-out-sm);
}
#fontSizeSlider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: none;
}

#fontSizeLabel {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  min-width: 22px;
  text-align: center;
}

/* Layout controls */
.layout-controls {
  display: flex;
  gap: 4px;
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 4px;
  box-shadow: var(--shadow-out-sm);
}

.layout-btn {
  background: none;
  border: none;
  border-radius: 12px;
  padding: 6px 10px;
  cursor: pointer;
  color: var(--text-muted);
  transition: var(--transition);
  display: flex;
  align-items: center;
  font-size: 0.95rem;
}
.layout-btn:hover { color: var(--text); }
.layout-btn.active {
  background: var(--card-bg);
  color: var(--accent);
  box-shadow: var(--shadow-in);
}

/* Fullscreen button */
.fullscreen-btn {
  background: var(--accent);
  color: white;
  border: none;
  border-radius: var(--radius);
  width: 40px;
  height: 40px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  box-shadow: var(--shadow-out-sm);
}
.fullscreen-btn:hover {
  box-shadow: var(--shadow-in);
  transform: scale(1.05);
}
.fullscreen-btn .material-symbols-outlined {
  font-size: 1.4rem;
}

/* Dark mode button */
.darkmode-btn {
  background: var(--card-bg);
  color: var(--text-muted);
  border: none;
  border-radius: var(--radius);
  width: 40px;
  height: 40px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  box-shadow: var(--shadow-out-sm);
}
.darkmode-btn:hover {
  box-shadow: var(--shadow-in);
  color: var(--accent);
}
.darkmode-btn.active {
  color: var(--accent);
  box-shadow: var(--shadow-in);
}

/* Batch edit button */
.batch-edit-btn.hidden { display: none; }

/* Selection bar */
.selection-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  margin-bottom: 12px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-out-sm);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--text);
}
.selection-bar.hidden { display: none; }

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

.clear-selection-btn {
  background: none;
  border: 1px solid var(--text-muted);
  border-radius: 8px;
  padding: 4px 14px;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  cursor: pointer;
  color: var(--text-muted);
  transition: var(--transition);
}
.clear-selection-btn:hover {
  border-color: var(--danger);
  color: var(--danger);
}

/* Card selection checkbox - only visible in select mode */
.card-select {
  position: absolute;
  top: 10px;
  left: 10px;
  width: 28px;
  height: 28px;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 3;
  color: var(--text-light);
  transition: var(--transition);
}
.select-mode .card-select {
  display: flex;
}
.card-select .select-icon {
  font-size: 1.6rem;
  font-variation-settings: 'FILL' 0;
}
.card-select:hover .select-icon {
  color: var(--accent);
}
.homework-card.selected {
  box-shadow: 0 0 0 2px var(--accent), var(--shadow-out);
}
.homework-card.selected .card-select .select-icon {
  color: var(--accent);
  font-variation-settings: 'FILL' 1;
}

/* ========== Display Mode (全屏大字显示) ========== */
.display-mode {
  background: var(--bg);
  min-height: 100vh;
}
.display-mode .header {
  display: none;
}
.display-mode .font-size-control,
.display-mode .layout-controls,
.display-mode .toolbar-btn,
.display-mode .selection-bar {
  display: none !important;
}
.display-mode .header-inner {
  padding: 12px 40px;
}
.display-mode .main {
  background: var(--bg);
  min-height: 100vh;
  padding: 16px 24px 24px;
}
.display-mode .card-wall {
  gap: 14px;
  height: calc(100vh - 80px);
  grid-auto-rows: 1fr;
}
.display-mode .logo {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: 0.02em;
}
.display-mode .homework-card {
  padding: 12px 20px;
  background: var(--card-bg);
  box-shadow: var(--shadow-out);
  margin-bottom: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.display-mode .card-top {
  display: none;
}
.display-mode .card-subject {
  font-weight: 800;
  letter-spacing: 0.02em;
  margin-bottom: 0;
}
.display-mode .card-content {
  font-weight: 500;
}
.display-mode .card-note {
  display: block;
}
.display-mode .card-drag-handle {
  display: none;
}
.display-mode .card-actions {
  opacity: 1;
}
.display-mode .card-select {
  display: none !important;
}
.display-mode .card-action-btn {
  width: 40px;
  height: 40px;
  font-size: 1.1rem;
}
.display-mode .fullscreen-btn {
  width: 44px;
  height: 44px;
  box-shadow: 0 0 0 2px white, var(--shadow-out);
}
.display-mode .empty-icon {
  font-size: 5rem;
}
.display-mode .empty-text {
  font-size: 1.8rem;
}

/* ========== Main Layout ========== */
.main {
  max-width: 100%;
  margin: 0 auto;
  padding: 32px 40px 80px;
}

/* Toolbar */
.toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 28px;
}

.toolbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

/* Batch import button */
.batch-import-btn {
  font-family: var(--font-sans);
  background: var(--success);
  color: white;
  border: none;
  border-radius: var(--radius);
  padding: 10px 18px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 6px;
  box-shadow: var(--shadow-out-sm);
}
.batch-import-btn:hover {
  box-shadow: var(--shadow-in);
  filter: brightness(1.05);
}

.modal-wide {
  max-width: 640px;
}

.batch-hint {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 12px;
  padding: 0 28px;
}

#batchInput {
  width: calc(100% - 56px);
  margin: 0 28px;
  padding: 14px;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--card-bg);
  resize: vertical;
  box-shadow: var(--shadow-in);
  transition: var(--transition);
  line-height: 1.7;
}
#batchInput:focus {
  outline: none;
  box-shadow: var(--shadow-in-strong);
}

.modal-body {
  padding: 20px 0 28px;
}
.modal-body .form-group {
  padding: 0 28px;
}
.modal-body .form-actions {
  padding: 0 28px;
}

.homework-count {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
}

/* Unified toolbar buttons */
.toolbar-btn {
  font-family: var(--font-sans);
  background: var(--card-bg);
  color: var(--text);
  border: none;
  border-radius: var(--radius);
  padding: 10px 18px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 6px;
  box-shadow: var(--shadow-out-sm);
}
.toolbar-btn:hover {
  box-shadow: var(--shadow-in);
  color: var(--accent);
}
.toolbar-btn.hidden { display: none; }
.toolbar-btn.active {
  background: var(--accent);
  color: white;
  box-shadow: var(--shadow-in);
}

.toolbar-btn-primary {
  background: var(--accent);
  color: white;
  box-shadow: var(--shadow-out-sm);
}
.toolbar-btn-primary:hover {
  background: var(--accent-light);
  box-shadow: var(--shadow-in);
  color: white;
}

/* ========== Card Wall ========== */
.card-wall {
  display: grid;
  gap: 20px;
  min-height: 200px;
}
.card-wall[data-layout="1"] { grid-template-columns: 1fr; }
.card-wall[data-layout="2"] { grid-template-columns: repeat(2, 1fr); }
.card-wall[data-layout="3"] { grid-template-columns: repeat(3, 1fr); }

/* ========== Neumorphism Card ========== */
.homework-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 28px 32px 36px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  animation: cardIn 0.25s ease;
  position: relative;
  transition: var(--transition);
  box-shadow: var(--shadow-out);
}

.homework-card:hover {
  box-shadow: var(--shadow-out);
}

/* Card completed state */
.homework-card.completed {
  opacity: 0.5;
  text-decoration: line-through;
}

/* Drag handle */
.card-drag-handle {
  position: absolute;
  bottom: 8px;
  right: 10px;
  color: var(--text-light);
  cursor: grab;
  font-size: 1.1rem;
  padding: 6px;
  border-radius: 8px;
  transition: var(--transition);
  user-select: none;
  -webkit-user-select: none;
  z-index: 1;
}
.card-drag-handle:hover { color: var(--accent); }
.homework-card:active .card-drag-handle { cursor: grabbing; }

/* Card top row */
.card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 8px;
}

/* Card actions - absolute top-right */
.card-actions {
  position: absolute;
  top: 8px;
  right: 8px;
  display: flex;
  gap: 4px;
  opacity: 0;
  transition: var(--transition);
  z-index: 2;
}
.homework-card:hover .card-actions { opacity: 1; }

.card-action-btn {
  background: var(--card-bg);
  border: none;
  border-radius: 10px;
  width: 34px;
  height: 34px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  color: var(--text-muted);
  font-size: 0.9rem;
  box-shadow: var(--shadow-out-sm);
}
.card-action-btn:hover { box-shadow: var(--shadow-in); color: var(--text); }
.card-action-btn.delete:hover { color: var(--danger); }

/* Card subject */
.card-subject {
  font-family: var(--font-sans);
  display: block;
  font-size: calc(var(--card-font-size) * 1.15);
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 0;
}

/* Card content */
.card-content {
  font-family: var(--font-sans);
  font-size: var(--card-font-size);
  font-weight: 400;
  color: var(--text);
  word-break: break-word;
  white-space: pre-wrap;
  line-height: 1.5;
  flex: 1;
}

.card-note {
  font-family: var(--font-sans);
  font-size: calc(var(--card-font-size) * 0.65);
  font-weight: 400;
  color: var(--text-muted);
  margin-top: 2px;
}

/* Drag state */
.homework-card.dragging {
  opacity: 0.4;
  box-shadow: var(--shadow-in);
}

.card-wall.drag-over .homework-card.drag-target {
  box-shadow: 0 0 0 2px var(--accent);
}

@keyframes cardIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ========== Empty State ========== */
.empty-state {
  grid-column: 1 / -1;
  text-align: center;
  padding: 100px 20px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-out);
}

.empty-icon {
  font-size: 3.5rem;
  margin-bottom: 16px;
  color: var(--text-light);
}

.empty-text {
  font-family: var(--font-sans);
  font-size: 1.1rem;
  font-weight: 400;
  color: var(--text-muted);
  line-height: 1.8;
}

/* ========== Modal ========== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.25);
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
  animation: fadeIn 0.15s ease;
}
.modal-overlay.hidden { display: none; }

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

.modal {
  background: var(--card-bg);
  border-radius: var(--radius);
  width: 100%;
  max-width: 500px;
  box-shadow: var(--shadow-out);
  animation: modalSlide 0.2s ease;
}

@keyframes modalSlide {
  from { transform: translateY(12px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px 28px 0;
}
.modal-header h2 {
  font-family: var(--font-sans);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text);
}

.modal-close {
  background: var(--card-bg);
  border: none;
  border-radius: 10px;
  font-size: 1.4rem;
  cursor: pointer;
  color: var(--text-muted);
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  box-shadow: var(--shadow-out-sm);
}
.modal-close:hover { box-shadow: var(--shadow-in); color: var(--text); }

#homeworkForm { padding: 20px 28px 28px; }

.form-group { margin-bottom: 18px; }

.form-group label {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.form-group select,
.form-group textarea,
.form-group input {
  width: 100%;
  padding: 12px 14px;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  color: var(--text);
  background: var(--card-bg);
  transition: var(--transition);
  box-shadow: var(--shadow-in);
}
.form-group select:focus,
.form-group textarea:focus,
.form-group input:focus {
  outline: none;
  box-shadow: var(--shadow-in-strong);
}
.form-group textarea { resize: vertical; min-height: 80px; }

.form-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  margin-top: 24px;
}

.btn-cancel, .btn-submit {
  padding: 12px 28px;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.btn-cancel {
  background: var(--card-bg);
  color: var(--text-muted);
  box-shadow: var(--shadow-out-sm);
}
.btn-cancel:hover { box-shadow: var(--shadow-in); color: var(--text); }

.btn-submit {
  background: var(--accent);
  color: white;
  box-shadow: var(--shadow-out-sm);
}
.btn-submit:hover { box-shadow: var(--shadow-in); }

/* ========== Toast ========== */
.toast-container {
  position: fixed;
  bottom: 32px;
  right: 32px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 2000;
}

.toast {
  background: var(--card-bg);
  color: var(--text);
  padding: 14px 24px;
  border-radius: var(--radius);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  box-shadow: var(--shadow-out);
  animation: toastIn 0.25s ease;
}
.toast.success { color: var(--success); }
.toast.error { color: var(--danger); }

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

/* ========== Responsive ========== */
@media (max-width: 900px) {
  .card-wall[data-layout="2"] { grid-template-columns: 1fr 1fr; }
  .card-wall[data-layout="3"] { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  .header-inner { padding: 12px 16px; flex-direction: column; gap: 8px; }
  .header-left, .header-center, .header-right { width: 100%; justify-content: center; }
  .header-right { flex-wrap: wrap; }
  .logo { font-size: 1rem; }
  #dateLabel { font-size: 0.85rem; }
  #fontSizeSlider { width: 50px; }
  .main { padding: 20px 16px 80px; }
  .card-wall[data-layout="2"],
  .card-wall[data-layout="3"] { grid-template-columns: 1fr; }
  .card-actions { opacity: 1; }
  .homework-card { padding: 20px 20px 32px; }
}

/* ========== Touch Device ========== */
@media (hover: none) {
  .card-actions { opacity: 1; }
  .card-action-btn { width: 40px; height: 40px; }
  .card-drag-handle { padding: 10px; }
}

/* ========== Dark Mode ========== */
body.dark-mode {
  --bg: #1a1a2e;
  --bg-light: #22223a;
  --card-bg: #25253e;
  --accent: #a29bfe;
  --accent-light: #bdb2ff;
  --text: #e8e8f0;
  --text-muted: #8888aa;
  --text-light: #666688;
  --success: #00d2a0;
  --danger: #ff6b6b;

  --shadow-out: 8px 8px 16px rgba(0,0,0,0.35),
                -8px -8px 16px rgba(255,255,255,0.04);
  --shadow-out-sm: 4px 4px 8px rgba(0,0,0,0.3),
                   -4px -4px 8px rgba(255,255,255,0.03);
  --shadow-in: inset 3px 3px 7px rgba(0,0,0,0.35),
               inset -3px -3px 7px rgba(255,255,255,0.04);
  --shadow-in-strong: inset 4px 4px 10px rgba(0,0,0,0.4),
                      inset -4px -4px 10px rgba(255,255,255,0.05);
}

/* Follow system preference */
@media (prefers-color-scheme: dark) {
  body:not(.light-mode) {
    --bg: #1a1a2e;
    --bg-light: #22223a;
    --card-bg: #25253e;
    --accent: #a29bfe;
    --accent-light: #bdb2ff;
    --text: #e8e8f0;
    --text-muted: #8888aa;
    --text-light: #666688;
    --success: #00d2a0;
    --danger: #ff6b6b;

    --shadow-out: 8px 8px 16px rgba(0,0,0,0.35),
                  -8px -8px 16px rgba(255,255,255,0.04);
    --shadow-out-sm: 4px 4px 8px rgba(0,0,0,0.3),
                     -4px -4px 8px rgba(255,255,255,0.03);
    --shadow-in: inset 3px 3px 7px rgba(0,0,0,0.35),
                 inset -3px -3px 7px rgba(255,255,255,0.04);
    --shadow-in-strong: inset 4px 4px 10px rgba(0,0,0,0.4),
                        inset -4px -4px 10px rgba(255,255,255,0.05);
  }
}