/* ===== Variables & Reset ===== */
*{margin:0;padding:0;box-sizing:border-box}

:root{
  --bg:#f0f2f5;
  --sidebar-bg:#ffffff;
  --editor-bg:#ffffff;
  --text:#1d1d1f;
  --text-secondary:#6e6e73;
  --border:#e0e0e5;
  --accent:#0071e3;
  --accent-light:#e8f2ff;
  --accent-hover:#0060c0;
  --danger:#ff3b30;
  --tag-bg:#e8e8ed;
  --tag-text:#424245;
  --note-hover:#f5f5fa;
  --note-active:#e8f2ff;
  --pinned-bg:#fff7e6;
  --radius:10px;
  --radius-sm:6px;
  --radius-lg:14px;
  --sidebar-width:300px;
  --transition:.2s ease;
  --shadow-sm:0 1px 3px rgba(0,0,0,0.06);
  --shadow-md:0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg:0 8px 24px rgba(0,0,0,0.12);
}

[data-theme=dark]{
  --bg:#1c1c1e;
  --sidebar-bg:#2c2c2e;
  --editor-bg:#2c2c2e;
  --text:#f5f5f7;
  --text-secondary:#98989d;
  --border:#3a3a3c;
  --accent:#0a84ff;
  --accent-light:#1a3a5c;
  --accent-hover:#409cff;
  --danger:#ff453a;
  --tag-bg:#3a3a3c;
  --tag-text:#d1d1d6;
  --note-hover:#3a3a3c;
  --note-active:#1a3a5c;
  --pinned-bg:#3a3520;
  --shadow-sm:0 1px 3px rgba(0,0,0,0.2);
  --shadow-md:0 4px 12px rgba(0,0,0,0.25);
  --shadow-lg:0 8px 24px rgba(0,0,0,0.3);
}

body{
  font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans SC,sans-serif;
  background:var(--bg);
  color:var(--text);
  height:100vh;
  overflow:hidden;
  -webkit-font-smoothing:antialiased;
}

/* ===== Login Screen ===== */
#app{display:flex;height:100vh}
#app.app-hidden{display:none}

#login-screen{
  position:fixed;inset:0;z-index:9999;
  display:flex;align-items:center;justify-content:center;
  background:var(--bg);
  flex-direction:column
}

#login-form{
  background:var(--sidebar-bg);
  padding:40px;
  border-radius:var(--radius-lg);
  box-shadow:var(--shadow-lg);
  width:380px;
  text-align:center;
  animation:fadeInUp .35s ease
}

#login-form h1{font-size:26px;margin-bottom:4px;letter-spacing:-.5px}
#login-form input{
  width:100%;padding:10px 14px;margin-bottom:12px;
  border:1px solid var(--border);border-radius:var(--radius-sm);
  font-size:14px;background:var(--bg);color:var(--text);outline:none;
  transition:border-color var(--transition),box-shadow var(--transition)
}
#login-form input:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(0,113,227,.15)}
.login-description{margin-bottom:16px;color:var(--text-secondary);font-size:14px}
.token-hint{font-size:12px;color:var(--text-secondary);margin-bottom:12px}
.token-link{color:var(--accent);text-decoration:none}
.token-link:hover{text-decoration:underline}
#login-error{display:none;color:var(--danger);font-size:13px;margin-top:10px}
#login-form button{
  width:100%;padding:10px;
  background:var(--accent);color:#fff;
  border:none;border-radius:var(--radius-sm);
  font-size:15px;font-weight:600;cursor:pointer;
  margin-top:4px;transition:background var(--transition),transform .1s
}
#login-form button:hover{background:var(--accent-hover)}
#login-form button:active{transform:scale(.98)}

/* ===== Sidebar ===== */
#sidebar{
  width:var(--sidebar-width);min-width:var(--sidebar-width);
  background:var(--sidebar-bg);
  border-right:1px solid var(--border);
  display:flex;flex-direction:column
}

.sidebar-header{
  display:flex;align-items:center;justify-content:space-between;
  padding:16px 16px 12px
}
.sidebar-header h1{font-size:18px;font-weight:700;letter-spacing:-.5px}

#new-note-btn{
  width:34px;height:34px;
  background:var(--accent);color:#fff;
  border:none;border-radius:var(--radius-sm);
  cursor:pointer;display:flex;align-items:center;justify-content:center;
  transition:background var(--transition),transform .1s
}
#new-note-btn:hover{background:var(--accent-hover)}
#new-note-btn:active{transform:scale(.92)}

.search-box{
  margin:0 16px 10px;
  display:flex;align-items:center;gap:8px;
  background:var(--bg);
  border:1px solid var(--border);
  border-radius:var(--radius-sm);
  padding:7px 10px;
  transition:border-color var(--transition),box-shadow var(--transition)
}
.search-box:focus-within{border-color:var(--accent);box-shadow:0 0 0 3px rgba(0,113,227,.1)}
.search-box svg{color:var(--text-secondary);flex-shrink:0}
.search-box input{flex:1;border:none;background:transparent;font-size:14px;color:var(--text);outline:none}

.tag-filter{
  display:flex;flex-wrap:wrap;gap:6px;
  padding:0 16px 12px
}
.tag-filter .tag{
  font-size:12px;padding:3px 10px;border-radius:20px;
  background:var(--tag-bg);color:var(--tag-text);
  cursor:pointer;transition:all var(--transition);
  border:1px solid transparent;
  -webkit-user-select:none;
  user-select:none
}
.tag-filter .tag:hover,.tag-filter .tag.active{
  background:var(--accent-light);color:var(--accent);border-color:var(--accent)
}

.note-list{flex:1;overflow-y:auto;padding:0 6px}
.note-list::-webkit-scrollbar{width:5px}
.note-list::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}

.note-item{
  position:relative;
  padding:12px 30px 12px 14px;
  border-radius:var(--radius);
  cursor:pointer;transition:background var(--transition);
  margin-bottom:2px
}
.note-item.dragging{opacity:.4}
.pin-btn{
  position:absolute;top:8px;right:6px;
  width:22px;height:22px;
  background:transparent;color:var(--text-secondary);
  border:none;border-radius:4px;font-size:13px;cursor:pointer;
  display:flex;align-items:center;justify-content:center;
  padding:0;opacity:0;pointer-events:none
}
.note-item:hover .pin-btn{opacity:1}
.pin-btn.pinned{opacity:1}
.pin-btn:hover{color:var(--accent)}

.drop-indicator{height:2px;background:var(--accent);border-radius:1px;margin:0 8px;pointer-events:none;display:none}

/* ===== Pinned section ===== */
.pinned-section{position:sticky;top:0;background:var(--sidebar-bg);z-index:2}
.pinned-section .note-item{background:var(--pinned-bg);border-radius:var(--radius)}
.pinned-section .note-item:first-child{margin-top:2px}
.pinned-divider{height:1px;background:var(--border);margin:2px 8px 4px}
.note-item:hover{background:var(--note-hover)}
.note-item.active{background:var(--note-active)}
.note-item-title{font-size:14px;font-weight:600;margin-bottom:4px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.note-item-preview{font-size:12px;color:var(--text-secondary);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.note-item-meta{display:flex;justify-content:space-between;align-items:center;margin-top:6px;font-size:11px;color:var(--text-secondary)}
.note-item-tags{display:flex;gap:4px}
.note-item-tags span{font-size:10px;padding:1px 6px;border-radius:8px;background:var(--tag-bg);color:var(--tag-text)}

.sidebar-footer{
  display:flex;align-items:center;justify-content:space-between;
  padding:12px 16px;border-top:1px solid var(--border);
  margin-top:auto
}
.sidebar-footer .note-count{font-size:12px;color:var(--text-secondary)}
#logout-btn{
  background:none;border:none;color:var(--text-secondary);
  cursor:pointer;font-size:12px;transition:color var(--transition)
}
#logout-btn:hover{color:var(--accent);text-decoration:underline}

/* ===== Editor Area ===== */
#editor-area{flex:1;display:flex;flex-direction:column;background:var(--editor-bg);overflow:hidden}

.empty-state{
  flex:1;display:flex;flex-direction:column;
  align-items:center;justify-content:center;color:var(--text-secondary)
}
.empty-icon{font-size:72px;margin-bottom:16px;opacity:.6}
.empty-state h2{font-size:22px;margin-bottom:8px;color:var(--text);font-weight:600}
.empty-state p{font-size:14px;margin-bottom:4px}
.shortcut-hint{margin-top:16px;font-size:12px}
kbd{background:var(--tag-bg);padding:2px 7px;border-radius:4px;font-size:11px;font-family:inherit;border:1px solid var(--border)}

#editor-view{flex:1;display:flex;flex-direction:column;overflow:hidden}

.editor-toolbar{
  display:flex;align-items:center;justify-content:space-between;
  padding:12px 24px;
  border-bottom:1px solid var(--border);
  gap:12px
}
#note-title{
  flex:1;font-size:20px;font-weight:700;
  border:none;background:transparent;color:var(--text);
  outline:none;letter-spacing:-.3px
}
#note-title::placeholder{color:var(--text-secondary)}

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

.tag-input-wrapper{
  display:flex;align-items:center;gap:6px;
  background:var(--bg);border:1px solid var(--border);
  border-radius:var(--radius-sm);padding:4px 8px;
  transition:border-color var(--transition)
}
.tag-input-wrapper:focus-within{border-color:var(--accent)}
.tag-input-wrapper svg{color:var(--text-secondary);flex-shrink:0}
#tag-input{border:none;background:transparent;font-size:13px;color:var(--text);outline:none;width:140px}

.icon-btn{
  width:34px;height:34px;
  background:none;border:1px solid var(--border);
  border-radius:var(--radius-sm);
  cursor:pointer;color:var(--text-secondary);
  display:flex;align-items:center;justify-content:center;
  transition:all var(--transition)
}
.icon-btn:hover{background:var(--note-hover);color:var(--text);border-color:var(--text-secondary)}
.icon-btn.danger:hover{background:#fff0f0;color:var(--danger);border-color:var(--danger)}
[data-theme=dark] .icon-btn.danger:hover{background:#3a1c1c}

.tag-bar{
  display:flex;flex-wrap:wrap;gap:6px;
  padding:0 24px 8px;min-height:0
}
.tag-bar:empty{display:none;padding:0}
.tag-bar .tag{
  display:flex;align-items:center;gap:4px;
  font-size:12px;padding:2px 10px;
  border-radius:20px;
  background:var(--accent-light);color:var(--accent);
  font-weight:500
}
.tag-bar .tag button{
  background:none;border:none;color:inherit;
  cursor:pointer;font-size:14px;line-height:1;
  padding:0 2px;opacity:.6;transition:opacity var(--transition)
}
.tag-bar .tag button:hover{opacity:1}

#note-content{
  flex:1;padding:16px 24px;
  border:none;background:transparent;
  color:var(--text);font-size:15px;line-height:1.8;
  resize:none;outline:none;
  font-family:SF Mono,Fira Code,Consolas,monospace
}
#note-content::placeholder{color:var(--text-secondary)}

.preview-content{
  flex:1;padding:16px 24px;overflow-y:auto;
  font-size:15px;line-height:1.8
}
.preview-content h1,.preview-content h2,.preview-content h3{margin:20px 0 10px;font-weight:700;line-height:1.3}
.preview-content h1{font-size:26px}.preview-content h2{font-size:21px}.preview-content h3{font-size:18px}
.preview-content p{margin-bottom:12px;color:var(--text)}
.preview-content code{
  background:var(--tag-bg);padding:2px 7px;border-radius:4px;
  font-size:13px;font-family:SF Mono,Fira Code,Consolas,monospace
}
.preview-content pre{
  background:var(--bg);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:14px 18px;overflow-x:auto;margin-bottom:16px
}
.preview-content pre code{background:none;padding:0}
.preview-content blockquote{
  border-left:3px solid var(--accent);padding-left:14px;
  color:var(--text-secondary);margin-bottom:12px;
  font-style:italic
}
.preview-content ul,.preview-content ol{padding-left:24px;margin-bottom:12px}
.preview-content li{margin-bottom:4px}
.preview-content a{color:var(--accent);text-decoration:none;font-weight:500}
.preview-content a:hover{text-decoration:underline}
.preview-content hr{border:none;border-top:1px solid var(--border);margin:20px 0}
.preview-content table{border-collapse:collapse;width:100%;margin:16px 0;font-size:14px;border-radius:var(--radius-sm);overflow:hidden}
.preview-content th,.preview-content td{border:1px solid var(--border);padding:10px 14px;text-align:left}
.preview-content th{background:var(--tag-bg);font-weight:600}
.preview-content tr:nth-child(even){background:var(--note-hover)}
.preview-content .katex-display{margin:16px 0;overflow-x:auto;overflow-y:hidden}
.preview-content .katex{font-size:1.1em}
.preview-content pre code.hljs{padding:0}
.preview-content .mindmap-container{
  width:100%;min-height:400px;
  margin:16px 0;padding:8px;
  border:1px solid var(--border);
  border-radius:var(--radius);
  background:var(--bg);overflow:hidden
}
.preview-content .mindmap-container svg{width:100%;height:100%;min-height:380px}

.editor-footer{
  display:flex;justify-content:space-between;
  padding:8px 24px;
  border-top:1px solid var(--border);
  font-size:12px;color:var(--text-secondary)
}

::-webkit-scrollbar{width:6px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}
::-webkit-scrollbar-thumb:hover{background:var(--text-secondary)}

/* ===== Drag-and-drop overlay ===== */
.drop-overlay{
  position:fixed;inset:0;
  background:rgba(0,0,0,0.45);
  z-index:1000;
  display:flex;align-items:center;justify-content:center;
  pointer-events:none;
  backdrop-filter:blur(4px);
  -webkit-backdrop-filter:blur(4px)
}
.drop-overlay-inner{
  background:var(--sidebar-bg);
  border:2px dashed var(--accent);
  border-radius:var(--radius-lg);
  padding:48px 64px;
  text-align:center;
  color:var(--text-primary);
  font-size:16px;
  animation:fadeInUp .2s ease
}
.drop-overlay-inner svg{margin-bottom:12px}

/* ===== Mobile ===== */
@media (max-width: 768px) {
  body{overflow:hidden}
  #login-form{width:calc(100vw - 32px);padding:28px 20px;border-radius:var(--radius)}
  #sidebar{position:fixed;inset:0;z-index:100;width:100vw;min-width:0;transition:transform var(--transition)}
  #sidebar.hidden{transform:translateX(-100%)}
  #editor-area{width:100vw}
  .mobile-topbar{
    display:flex;align-items:center;gap:8px;
    padding:10px 12px;
    border-bottom:1px solid var(--border);
    background:var(--editor-bg)
  }
  .mobile-topbar .back-btn{
    width:34px;height:34px;
    background:none;border:1px solid var(--border);border-radius:var(--radius-sm);
    cursor:pointer;color:var(--text-secondary);
    display:flex;align-items:center;justify-content:center;flex-shrink:0;
    transition:all var(--transition)
  }
  .mobile-topbar .back-btn:hover{background:var(--note-hover);color:var(--text)}
  .mobile-topbar .topbar-title{flex:1;font-size:15px;font-weight:600;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--text)}
  .mobile-topbar .topbar-actions{display:flex;gap:6px}
  .editor-toolbar{flex-wrap:wrap;padding:10px 14px;gap:8px}
  #note-title{font-size:17px;order:-1;flex-basis:100%}
  .toolbar-actions{gap:6px}
  .tag-input-wrapper{display:none}
  .tag-bar{padding:0 14px 6px}
  .mobile-tag-add{
    display:inline-flex;align-items:center;gap:3px;
    font-size:12px;padding:2px 10px;border-radius:20px;
    background:var(--tag-bg);color:var(--text-secondary);
    cursor:pointer;border:1px dashed var(--border);
    transition:all var(--transition)
  }
  .mobile-tag-add:hover{border-color:var(--accent);color:var(--accent)}
  .pin-btn{visibility:visible;opacity:1}
  #note-content,.preview-content{padding:12px 14px;font-size:15px}
  .editor-footer{padding:6px 14px}
  .empty-icon{font-size:48px;margin-bottom:12px}
  .empty-state h2{font-size:18px}
  .shortcut-hint{display:none}
  #sync-status{bottom:12px;right:12px;left:12px;text-align:center}
}

@media (min-width: 769px){
  .mobile-topbar{display:none}
  .mobile-tag-add{display:none}
}

/* ===== Utility ===== */
.hidden-input{display:none}

/* ===== Sync Status ===== */
.sync-status{
  display:none;
  position:fixed;bottom:20px;right:20px;
  background:var(--sidebar-bg);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:10px 18px;
  font-size:13px;
  font-weight:500;
  box-shadow:var(--shadow-md);
  z-index:999;
  animation:fadeInUp .2s ease
}

/* ===== Attachments ===== */
.attachment-bar{
  display:flex;flex-wrap:wrap;gap:8px;
  padding:0 24px 8px;min-height:0
}
.attachment-bar:empty{display:none;padding:0}
.attachment-item{
  display:flex;align-items:center;gap:8px;
  padding:6px 10px;
  background:var(--bg);
  border:1px solid var(--border);
  border-radius:var(--radius-sm);
  font-size:12px;max-width:240px;cursor:default;
  transition:border-color var(--transition),box-shadow var(--transition)
}
.attachment-item:hover{border-color:var(--accent);box-shadow:0 0 0 2px rgba(0,113,227,.08)}
.attachment-thumb{width:32px;height:32px;border-radius:4px;object-fit:cover;flex-shrink:0;cursor:pointer}
.attachment-icon{width:32px;height:32px;display:flex;align-items:center;justify-content:center;flex-shrink:0;color:var(--text-secondary);font-size:18px}
.attachment-info{flex:1;min-width:0}
.attachment-name{white-space:nowrap;overflow:hidden;text-overflow:ellipsis;color:var(--text);font-weight:500}
.attachment-size{color:var(--text-secondary);font-size:11px}
.attachment-del{background:none;border:none;color:var(--text-secondary);cursor:pointer;font-size:16px;line-height:1;padding:2px;opacity:.5;flex-shrink:0;transition:opacity var(--transition)}
.attachment-del:hover{opacity:1;color:var(--danger)}
.attachment-upload-hint{
  display:flex;align-items:center;gap:6px;
  padding:6px 14px;
  background:var(--bg);
  border:1px dashed var(--border);
  border-radius:var(--radius-sm);
  font-size:12px;color:var(--text-secondary);
  cursor:pointer;transition:all var(--transition)
}
.attachment-upload-hint:hover{border-color:var(--accent);color:var(--accent);box-shadow:0 0 0 2px rgba(0,113,227,.06)}
.attachment-progress{font-size:11px;color:var(--accent);padding:4px 24px}

/* ===== Sidebar footer actions ===== */
.footer-actions{display:flex;align-items:center;gap:8px}
.icon-btn-sm{
  width:26px;height:26px;
  background:none;border:none;
  cursor:pointer;color:var(--text-secondary);
  display:flex;align-items:center;justify-content:center;
  border-radius:4px;transition:all var(--transition)
}
.icon-btn-sm:hover{background:var(--note-hover);color:var(--text)}

/* ===== Modal ===== */
.modal-overlay{
  position:fixed;inset:0;
  background:rgba(0,0,0,0.45);
  z-index:10000;
  display:flex;align-items:center;justify-content:center;
  backdrop-filter:blur(4px);
  -webkit-backdrop-filter:blur(4px)
}
.modal-box{
  background:var(--sidebar-bg);
  border-radius:var(--radius-lg);
  padding:28px 32px;
  width:420px;
  max-width:calc(100vw - 32px);
  box-shadow:var(--shadow-lg);
  animation:fadeInUp .2s ease
}
.modal-box h3{font-size:18px;margin-bottom:8px;font-weight:700}
.modal-desc{font-size:13px;color:var(--text-secondary);margin-bottom:16px;line-height:1.5}
.modal-box input{
  width:100%;padding:10px 14px;
  border:1px solid var(--border);border-radius:var(--radius-sm);
  font-size:14px;background:var(--bg);color:var(--text);
  outline:none;margin-bottom:16px;
  transition:border-color var(--transition),box-shadow var(--transition)
}
.modal-box input:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(0,113,227,.1)}
.modal-actions{display:flex;justify-content:flex-end;gap:8px}
.btn-secondary{
  padding:8px 18px;
  border:1px solid var(--border);border-radius:var(--radius-sm);
  background:transparent;color:var(--text);
  font-size:13px;cursor:pointer;
  transition:all var(--transition)
}
.btn-secondary:hover{background:var(--note-hover)}
.btn-primary{
  padding:8px 18px;
  border:none;border-radius:var(--radius-sm);
  background:var(--accent);color:#fff;
  font-size:13px;font-weight:600;cursor:pointer;
  transition:background var(--transition),transform .1s
}
.btn-primary:hover{background:var(--accent-hover)}
.btn-primary:active{transform:scale(.97)}
.modal-hint{font-size:12px;color:var(--text-secondary);margin-top:-8px;margin-bottom:12px;line-height:1.5}
.modal-hint a{color:var(--accent);text-decoration:none}
.modal-hint a:hover{text-decoration:underline}

/* ===== Image preview ===== */
.image-preview-box{position:relative;max-width:90vw;max-height:90vh;animation:scaleIn .2s ease}
.image-preview-box img{max-width:90vw;max-height:90vh;object-fit:contain;border-radius:var(--radius);box-shadow:var(--shadow-lg)}
.image-preview-close{
  position:absolute;top:-40px;right:-4px;
  background:none;border:none;
  color:#fff;font-size:32px;cursor:pointer;line-height:1;
  opacity:.7;transition:opacity var(--transition)
}
.image-preview-close:hover{opacity:1}

/* ===== Animations ===== */
@keyframes fadeInUp{
  from{opacity:0;transform:translateY(12px)}
  to{opacity:1;transform:translateY(0)}
}
@keyframes scaleIn{
  from{opacity:0;transform:scale(.92)}
  to{opacity:1;transform:scale(1)}
}

/* ===== Mobile attachment ===== */
@media (max-width: 768px) {
  .attachment-bar{padding:0 14px 6px;gap:6px}
  .attachment-item{max-width:100%}
  .modal-box{padding:20px}
}