:root[data-theme="dark"] {
    --bg-color: #0d0e15;
    --panel-bg: rgba(255, 255, 255, 0.03);
    --panel-border: rgba(255, 255, 255, 0.08);
    --text-primary: #ffffff;
    --text-secondary: #8b92a5;
    --accent-gradient: linear-gradient(135deg, #00f2fe 0%, #4facfe 100%);
    --accent-color: #00f2fe;
    --accent-glow: rgba(0, 242, 254, 0.3);
    --btn-bg: rgba(255, 255, 255, 0.05);
    --btn-hover: rgba(255, 255, 255, 0.1);
    --task-bg: rgba(255, 255, 255, 0.02);
    --task-completed: rgba(255, 255, 255, 0.01);
    --blob-1: rgba(0, 242, 254, 0.15);
    --blob-2: rgba(142, 45, 226, 0.15);
    --success: #00e676;
    --danger: #ff1744;
}

:root[data-theme="light"] {
    --bg-color: #f0f2f5;
    --panel-bg: rgba(255, 255, 255, 0.7);
    --panel-border: rgba(0, 0, 0, 0.05);
    --text-primary: #1a1b20;
    --text-secondary: #5f6368;
    --accent-gradient: linear-gradient(135deg, #0093E9 0%, #80D0C7 100%);
    --accent-color: #0093E9;
    --accent-glow: rgba(0, 147, 233, 0.3);
    --btn-bg: rgba(0, 0, 0, 0.04);
    --btn-hover: rgba(0, 0, 0, 0.08);
    --task-bg: rgba(255, 255, 255, 0.9);
    --task-completed: rgba(255, 255, 255, 0.5);
    --blob-1: rgba(0, 147, 233, 0.15);
    --blob-2: rgba(255, 117, 140, 0.15);
    --success: #00c853;
    --danger: #d50000;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Plus Jakarta Sans', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    transition: background-color 0.4s ease;
}

/* Ambient Background Blobs */
.ambient-background {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    z-index: -1;
    overflow: hidden;
    pointer-events: none;
}

.blob {
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    animation: drift 20s infinite ease-in-out alternate;
}

.blob-1 {
    width: 600px; height: 600px;
    background: var(--blob-1);
    top: -200px; left: -200px;
}

.blob-2 {
    width: 500px; height: 500px;
    background: var(--blob-2);
    bottom: -100px; right: -100px;
    animation-delay: -5s;
}

@keyframes drift {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(100px, 50px) scale(1.1); }
}

/* Main App Layout */
.app-container {
    width: 100%;
    max-width: 1200px;
    height: 90vh;
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: 30px;
    display: grid;
    grid-template-columns: 320px 1fr;
    overflow: hidden;
    box-shadow: 0 20px 50px rgba(0,0,0,0.2);
}

:root[data-theme="light"] .app-container {
    box-shadow: 0 20px 50px rgba(0,0,0,0.05);
}

/* Dashboard Sidebar */
.dashboard {
    padding: 40px;
    border-right: 1px solid var(--panel-border);
    display: flex;
    flex-direction: column;
    gap: 40px;
}

.profile-section {
    display: flex;
    align-items: center;
    gap: 15px;
}

.avatar {
    width: 50px; height: 50px;
    border-radius: 50%;
    background: var(--accent-gradient);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    color: white;
}

.user-info h2 {
    font-size: 1.2rem;
    font-weight: 700;
}

.user-info p {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.progress-section {
    text-align: center;
}

.progress-section h3 {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    text-align: left;
}

.progress-ring-container {
    position: relative;
    display: inline-flex;
    justify-content: center;
    align-items: center;
}

.progress-ring__circle {
    stroke-dasharray: 326.72; /* 2 * pi * r (r=52) */
    stroke-dashoffset: 326.72;
    transition: stroke-dashoffset 1s ease-out;
}

.progress-text {
    position: absolute;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.progress-text span {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.progress-text small {
    font-size: 0.7rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-top: auto;
}

.stat-card {
    background: var(--btn-bg);
    border: 1px solid var(--panel-border);
    padding: 20px;
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-value {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Task Area */
.task-area {
    padding: 40px 50px;
    display: flex;
    flex-direction: column;
    height: 100%;
}

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

.task-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 5px;
}

.task-header p {
    color: var(--text-secondary);
    font-size: 1rem;
    font-style: italic;
}

.theme-btn {
    background: var(--btn-bg);
    border: 1px solid var(--panel-border);
    color: var(--text-primary);
    width: 45px; height: 45px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.2rem;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.3s;
}

.theme-btn:hover {
    background: var(--btn-hover);
    transform: rotate(15deg);
}

/* Input Area */
.input-container {
    display: flex;
    gap: 15px;
    margin-bottom: 30px;
    position: relative;
}

.add-btn {
    width: 50px; height: 50px;
    border-radius: 15px;
    border: none;
    background: var(--accent-gradient);
    color: white;
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: transform 0.2s, box-shadow 0.2s;
    flex-shrink: 0;
}

.add-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 5px 15px var(--accent-glow);
}

#task-input {
    flex: 1;
    background: var(--btn-bg);
    border: 1px solid var(--panel-border);
    border-radius: 15px;
    padding: 0 20px;
    color: var(--text-primary);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.3s;
}

#task-input:focus {
    border-color: var(--accent-color);
}

#task-category {
    background: var(--btn-bg);
    border: 1px solid var(--panel-border);
    border-radius: 15px;
    padding: 0 20px;
    color: var(--text-primary);
    font-size: 0.9rem;
    outline: none;
    cursor: pointer;
}

#task-category option {
    background: var(--bg-color);
    color: var(--text-primary);
}

/* Filters */
.filters {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
    border-bottom: 1px solid var(--panel-border);
    padding-bottom: 10px;
}

.filter-tab {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    position: relative;
    padding: 5px 0;
    transition: color 0.3s;
}

.filter-tab.active {
    color: var(--accent-color);
}

.filter-tab.active::after {
    content: '';
    position: absolute;
    bottom: -11px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--accent-color);
    border-radius: 2px;
}

/* Task List */
.task-list {
    list-style: none;
    overflow-y: auto;
    flex: 1;
    padding-right: 10px;
    display: flex;
    flex-direction: column;
    gap: 15px;
}

/* Custom Scrollbar */
.task-list::-webkit-scrollbar {
    width: 6px;
}
.task-list::-webkit-scrollbar-thumb {
    background: var(--panel-border);
    border-radius: 10px;
}

.task-item {
    background: var(--task-bg);
    border: 1px solid var(--panel-border);
    border-radius: 16px;
    padding: 20px;
    display: flex;
    align-items: center;
    gap: 15px;
    transition: all 0.3s;
    animation: slideIn 0.3s ease-out forwards;
}

.task-item:hover {
    border-color: var(--accent-color);
    transform: translateX(5px);
}

.task-item.completed {
    background: var(--task-completed);
    opacity: 0.7;
}

.task-item.completed:hover {
    border-color: var(--panel-border);
    transform: none;
}

.checkbox-custom {
    width: 24px; height: 24px;
    border-radius: 50%;
    border: 2px solid var(--text-secondary);
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    transition: all 0.2s;
    flex-shrink: 0;
}

.task-item.completed .checkbox-custom {
    background: var(--success);
    border-color: var(--success);
}

.checkbox-custom i {
    color: white;
    font-size: 0.9rem;
    opacity: 0;
    transition: opacity 0.2s;
}

.task-item.completed .checkbox-custom i {
    opacity: 1;
}

.task-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.task-text {
    font-size: 1.05rem;
    font-weight: 500;
    transition: color 0.3s;
}

.task-item.completed .task-text {
    text-decoration: line-through;
    color: var(--text-secondary);
}

.task-tag {
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    padding: 3px 8px;
    border-radius: 6px;
    align-self: flex-start;
}

.tag-personal { background: rgba(0, 242, 254, 0.1); color: #00f2fe; }
.tag-work { background: rgba(142, 45, 226, 0.1); color: #8e2de2; }
.tag-study { background: rgba(255, 117, 140, 0.1); color: #ff758c; }

:root[data-theme="light"] .tag-personal { color: #0093E9; }

.delete-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.2rem;
    cursor: pointer;
    transition: color 0.2s, transform 0.2s;
    opacity: 0;
}

.task-item:hover .delete-btn {
    opacity: 1;
}

.delete-btn:hover {
    color: var(--danger);
    transform: scale(1.1);
}

/* Animations */
@keyframes slideIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeOut {
    to { opacity: 0; transform: translateX(50px); }
}

/* Responsive */
@media (max-width: 900px) {
    .app-container {
        grid-template-columns: 1fr;
        height: 100vh;
        border-radius: 0;
    }
    
    .dashboard {
        border-right: none;
        border-bottom: 1px solid var(--panel-border);
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: space-between;
        padding: 20px 30px;
        gap: 20px;
    }
    
    .progress-section, .stats-grid {
        display: none; /* Hide complex stats on mobile to save space */
    }
    
    .task-area {
        padding: 20px 30px;
    }
}