@import url('https://fonts.googleapis.com/css2?family=Open+Sans:wght@300;400;500;600;700&family=Poppins:wght@400;500;600;700&display=swap');

:root {
    --bg-color: #f8fafc;
    --sidebar-bg: #ffffff;
    --main-bg: #ffffff;
    --primary: #3b82f6;
    --primary-light: #60a5fa;
    --cta: #f97316;
    --text-main: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --success: #22c55e;
    --danger: #ef4444;
    --warning: #f59e0b;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --modal-bg: rgba(255, 255, 255, 0.95);
}

[data-theme="dark"] {
    --bg-color: #0f172a;
    --sidebar-bg: #1e293b;
    --main-bg: #1e293b;
    --text-main: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --modal-bg: rgba(30, 41, 59, 0.95);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Open Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3,
.sidebar-header h2,
.list-header h1 {
    font-family: 'Poppins', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

.app-container {
    width: 100vw;
    height: 100vh;
    display: flex;
    background: var(--main-bg);
    overflow: hidden;
    position: relative;
    border: none;
}

/* Sidebar Styling */
.sidebar {
    width: 280px;
    padding: 30px 20px;
    background: var(--sidebar-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    z-index: 50;
    transition: transform 0.3s ease;
}

.sidebar-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 30px;
    padding-left: 10px;
}

.sidebar-header h2 {
    font-size: 22px;
    font-weight: 700;
    color: var(--primary);
}

.categories {
    flex: 1;
    overflow-y: auto;
}

.section-label {
    font-size: 11px;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    margin: 20px 0 10px 10px;
    letter-spacing: 1px;
}

.category-item {
    padding: 10px 16px;
    margin-bottom: 4px;
    border-radius: 10px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 12px;
}

.category-item:hover {
    background: rgba(59, 130, 246, 0.05);
    color: var(--primary);
}

.category-item.active {
    background: #eff6ff;
    color: var(--primary);
    font-weight: 600;
}

[data-theme="dark"] .category-item.active {
    background: rgba(59, 130, 246, 0.2);
}

.cat-delete-btn {
    margin-left: auto;
    opacity: 0;
    color: var(--text-secondary);
    background: none;
    border: none;
    cursor: pointer;
    transition: opacity 0.2s;
    padding: 4px;
    display: flex;
    align-items: center;
}

.category-item:hover .cat-delete-btn {
    opacity: 0.5;
}

.cat-delete-btn:hover {
    opacity: 1 !important;
    color: var(--danger);
}

.add-category-btn {
    margin-top: 10px;
    padding: 8px 16px;
    font-size: 13px;
    color: var(--primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
}

.sidebar-footer {
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

/* Main Content */
.main-content {
    flex: 1;
    padding: 60px 80px;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    background: var(--main-bg);
}

.list-header {
    margin-bottom: 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.menu-trigger {
    display: none;
    background: none;
    border: none;
    color: var(--text-main);
    cursor: pointer;
}

.list-header h1 {
    font-size: 36px;
    font-weight: 800;
    color: var(--text-main);
    letter-spacing: -1px;
}

.theme-toggle-btn {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    width: 48px;
    height: 48px;
    border-radius: 14px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.theme-toggle-btn:hover {
    color: var(--primary);
    border-color: var(--primary);
}

.theme-label {
    font-size: 8px;
    font-weight: 800;
    margin-top: -2px;
    text-transform: uppercase;
}

/* Add Task */
.add-task-container {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    padding: 24px;
    margin-bottom: 40px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

#new-task-input {
    flex: 1;
    padding: 14px 20px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background: var(--main-bg);
    font-size: 16px;
    outline: none;
    color: var(--text-main);
}

.options-group {
    display: flex;
    gap: 12px;
    align-items: center;
    flex-wrap: wrap;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 6px;
    background: var(--main-bg);
    padding: 8px 14px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    font-size: 14px;
    flex: 1;
    min-width: 150px;
}

.option-item select,
.option-item input {
    border: none;
    background: transparent;
    font-size: 14px;
    color: var(--text-main);
    outline: none;
    width: 100%;
}

#add-task-btn {
    padding: 0 24px;
    height: 42px;
    border: none;
    border-radius: 10px;
    background: var(--primary);
    color: white;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
}

/* Todo List */
.todo-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    overflow-x: hidden;
    /* 防止横向滚动条 */
}

.todo-item {
    position: relative;
    border-radius: 16px;
    border: 1px solid var(--border-color);
    background: var(--danger);
    /* 露出底色为红色，适配滑动 */
    padding: 0;
    /* Removing padding from container */
    overflow: hidden;
    display: flex;
    align-items: stretch;
}

.todo-main-view {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 18px 24px;
    background: var(--main-bg);
    position: relative;
    z-index: 2;
    width: 100%;
    transition: transform 0.2s cubic-bezier(0.2, 0.8, 0.2, 1);
    cursor: pointer;
}

.todo-item.swiped .todo-main-view {
    transform: translateX(-70px);
    border-radius: 16px 0 0 16px;
    /* 视觉优化 */
}

/* Empty State Fix */
.todo-item.empty {
    background: var(--main-bg) !important;
    /* 强制覆盖红色背景 */
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px !important;
    /* 恢复内边距 */
    gap: 16px;
    color: var(--text-secondary);
    border: 2px dashed var(--border-color);
    /* 使用虚线边框 */
    box-shadow: none;
    cursor: default;
}

.todo-item.empty:hover {
    box-shadow: none;
    border-color: var(--border-color);
}

.todo-item.empty p {
    font-size: 14px;
    font-weight: 500;
}

/* PC Hover Effect */
@media (min-width: 851px) {
    .todo-main-view:hover {
        border-color: var(--primary-light);
        /* box-shadow 移到 inner view? 不，shadow 应该在 item 上 */
    }

    .todo-item:hover {
        box-shadow: var(--shadow-md);
        border-color: var(--primary-light);
    }
}

.todo-content {
    flex: 1;
    overflow: hidden;
}

.todo-title {
    font-size: 16px;
    font-weight: 500;
    display: block;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.todo-meta {
    display: flex;
    gap: 12px;
    margin-top: 6px;
}

.priority-badge {
    font-size: 10px;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 6px;
}

.priority-高 {
    color: var(--danger);
    background: rgba(239, 68, 68, 0.15);
}

.priority-中 {
    color: var(--warning);
    background: rgba(245, 158, 11, 0.15);
}

.priority-低 {
    color: var(--success);
    background: rgba(34, 197, 94, 0.15);
}

.tag-category {
    font-size: 11px;
    color: var(--primary);
    background: rgba(59, 130, 246, 0.1);
    padding: 2px 10px;
    border-radius: 6px;
}

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

.delete-btn {
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    transition: all 0.2s;
}

/* Desktop Styles */
@media (min-width: 851px) {
    .todo-item {
        background: var(--main-bg);
        /* PC不需要红色底 */
    }

    .delete-btn {
        width: 50px;
        color: var(--text-secondary);
        opacity: 0;
        z-index: 3;
        background: var(--main-bg);
    }

    .todo-item:hover .delete-btn {
        opacity: 1;
        color: var(--danger);
    }
}

/* Mobile Swipe Styles */
@media (max-width: 850px) {
    .delete-btn {
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;
        width: 70px;
        background: var(--danger);
        color: white;
        z-index: 1;
        opacity: 1;
    }

    .todo-item {
        /* Mobile specific adjustments if needed */
    }
}

/* Modals - HIGH END REFINEMENT */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(12px);
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.modal-content {
    background: var(--modal-bg);
    padding: 36px;
    border-radius: 28px;
    width: 100%;
    max-width: 500px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    border: 1px solid var(--border-color);
    animation: modalIn 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes modalIn {
    from {
        opacity: 0;
        transform: scale(0.9) translateY(20px);
    }

    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.modal-header {
    margin-bottom: 28px;
}

.modal-header h2 {
    font-size: 24px;
    font-weight: 700;
    color: var(--text-main);
}

.form-field {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 24px;
}

.form-field label {
    font-size: 13px;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.form-field input,
.form-field select {
    padding: 14px 18px;
    border: 1px solid var(--border-color);
    border-radius: 14px;
    background: var(--bg-color);
    color: var(--text-main);
    font-size: 16px;
    transition: all 0.2s;
}

.form-field input:focus,
.form-field select:focus {
    border-color: var(--primary);
    background: var(--main-bg);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.1);
    outline: none;
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 16px;
    margin-top: 40px;
}

.btn-primary {
    padding: 14px 28px;
    background: var(--primary);
    color: white;
    border-radius: 14px;
    border: none;
    cursor: pointer;
    font-weight: 700;
    font-size: 15px;
    transition: all 0.2s;
}

.btn-primary:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(59, 130, 246, 0.3);
}

.btn-secondary {
    padding: 14px 28px;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 14px;
    cursor: pointer;
    color: var(--text-main);
    font-weight: 700;
    font-size: 15px;
    transition: all 0.2s;
}

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

.btn-danger {
    background: var(--danger);
    color: white;
}

.btn-danger:hover {
    background: #ff4d4d;
    box-shadow: 0 10px 15px -3px rgba(239, 68, 68, 0.3);
}

.data-safety-tip {
    background: rgba(34, 197, 94, 0.1);
    border: 1px solid rgba(34, 197, 94, 0.2);
    padding: 16px 20px;
    border-radius: 16px;
    font-size: 13px;
    color: var(--success);
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    line-height: 1.5;
}

/* Responsive */
@media (max-width: 850px) {
    .app-container {
        height: 100vh;
        border-radius: 0;
    }

    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        bottom: 0;
        transform: translateX(-100%);
        transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        box-shadow: 20px 0 50px rgba(0, 0, 0, 0.2);
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .menu-trigger {
        display: block;
    }

    .main-content {
        padding: 24px;
    }


}

@media (max-width: 500px) {
    .options-group {
        flex-direction: column;
        align-items: stretch;
    }

    #add-task-btn {
        width: 100%;
    }

    .modal-content {
        padding: 24px;
        border-radius: 20px;
    }

    .main-content {
        padding: 16px;
    }

    .list-header h1 {
        font-size: 24px;
    }

    .modal-footer {
        flex-direction: column;
    }

    .btn-primary,
    .btn-secondary {
        width: 100%;
    }
}

/* FAB Button Styling */
.fab-btn {
    position: fixed;
    bottom: 40px;
    right: 40px;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background-color: var(--primary);
    color: white;
    border: none;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
    z-index: 100;
}

.fab-btn:hover {
    transform: scale(1.1) rotate(90deg);
    background-color: var(--primary-light);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.5);
}

.fab-btn:active {
    transform: scale(0.95);
}

.fab-btn svg {
    width: 28px;
    height: 28px;
    stroke-width: 2.5;
}

@media (max-width: 500px) {
    .fab-btn {
        bottom: 24px;
        right: 24px;
        width: 56px;
        height: 56px;
    }
}