/* @budding: 页面框架与布局 */
.phone-screen {
    width: 100%; max-width: 420px; height: 100vh; max-height: 850px;
    background-color: var(--white-color); box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    border-radius: var(--phone-corner-radius); overflow: hidden;
    position: relative; display: flex; flex-direction: column;
}
.screen { display: none; flex-direction: column; width: 100%; height: 100%; animation: fadeIn 0.5s ease; }
.screen.active { display: flex; }
@keyframes fadeIn { from { opacity: 0; transform: scale(0.95); } to { opacity: 1; transform: scale(1); } }
@keyframes slideUp { from { transform: translateY(20px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }

.app-header {
    display: flex; justify-content: space-between; align-items: center;
    padding: 10px 20px; background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(10px); border-bottom: 1px solid #eee;
    flex-shrink: 0; position: relative; z-index: 10;
}
.app-header .back-btn, .app-header .action-btn {
    background: none; border: none; font-size: 24px; font-weight: bold;
    color: var(--secondary-color); cursor: pointer; width: 40px; height: 40px;
    display: flex; align-items: center; justify-content: center; transition: color 0.2s;
}
.app-header .back-btn:hover, .app-header .action-btn:hover { color: var(--primary-color); }
.app-header .title-container { display: flex; flex-direction: column; align-items: center; text-align: center; position: absolute; left: 50%; transform: translateX(-50%); }
.app-header .title { font-size: 18px; font-weight: 600; color: var(--text-color); margin: 0; }
.app-header .subtitle { font-size: 12px; color: #888; display: flex; align-items: center; margin-top: 2px; }
.online-indicator { width: 8px; height: 8px; border-radius: 50%; background-color: var(--online-status-color); margin-right: 5px; }
.app-header .placeholder { width: 40px; }
.content { flex-grow: 1; overflow-y: auto; padding: 20px; position: relative; }
.placeholder-text { text-align: center; color: #aaa; margin-top: 50px; }

/* 弹窗基础 */
.modal-overlay { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.4); z-index: 100; display: none; align-items: center; justify-content: center; animation: fadeIn 0.3s ease; }
.modal-overlay.visible { display: flex; }
.modal-window { background: var(--white-color); padding: 25px; border-radius: var(--border-radius); box-shadow: 0 5px 25px rgba(0, 0, 0, 0.15); width: 85%; max-width: 340px; animation: slideUp 0.4s ease-out; }
.modal-window h3 { margin-top: 0; text-align: center; color: var(--text-color); }
.context-menu { position: fixed; z-index: 1000; background: white; border-radius: 10px; box-shadow: 0 2px 10px rgba(0, 0, 0, 0.15); overflow: hidden; padding: 5px 0; animation: fadeIn 0.1s ease; }
.context-menu-item { padding: 10px 20px; cursor: pointer; }
.context-menu-item:hover { background-color: #f5f5f5; }
.context-menu-item.danger { color: #e53935; }
.action-sheet-overlay { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.4); z-index: 200; display: none; align-items: flex-end; animation: fadeIn 0.3s ease; }
.action-sheet-overlay.visible { display: flex; }
.action-sheet { background: #f7f7f7; width: 100%; border-top-left-radius: 20px; border-top-right-radius: 20px; padding: 10px; padding-bottom: calc(10px + env(safe-area-inset-bottom)); animation: slideUp 0.3s ease-out; }
.action-sheet-button { width: 100%; background: white; border: none; padding: 15px; font-size: 16px; color: var(--accent-color); font-weight: 500; cursor: pointer; border-radius: 10px; margin-bottom: 8px; transition: background-color 0.2s; }
.action-sheet-button:active { background-color: #f0f0f0; }
.action-sheet-button.danger { color: #e53935; }
.action-sheet-button:last-child { margin-bottom: 0; }

/* @budding: 修复顶部动作按钮（如聊天设置）图标变大的问题 */
.app-header .action-btn img {
    width: 28px;
    height: 28px;
}