:root {
    --bg-gradient-start: #0f172a;
    --bg-gradient-end: #1e1b4b;
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #8b5cf6;
    --accent-hover: #a78bfa;
    --success-color: #10b981;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start), var(--bg-gradient-end));
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 2rem;
    overflow-x: hidden;
}

body::before, body::after {
    content: '';
    position: fixed;
    border-radius: 50%;
    filter: blur(100px);
    z-index: -1;
    animation: float 10s infinite alternate;
}

body::before {
    width: 400px;
    height: 400px;
    background: rgba(139, 92, 246, 0.25);
    top: -100px;
    left: -100px;
}

body::after {
    width: 300px;
    height: 300px;
    background: rgba(16, 185, 129, 0.15);
    bottom: -50px;
    right: -50px;
    animation-delay: -5s;
}

@keyframes float {
    0% { transform: translate(0, 0); }
    100% { transform: translate(30px, 50px); }
}

.app-container {
    width: 100%;
    max-width: 800px;
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 2.5rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

header {
    text-align: center;
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, #a855f7, #ec4899);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

.progress-container {
    width: 100%;
    height: 8px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), var(--success-color));
    width: 0%;
    transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.progress-text {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.category {
    background: rgba(0, 0, 0, 0.2);
    border-radius: 16px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    border: 1px solid var(--glass-border);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.category:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
}

.category-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.category-title::before {
    content: '';
    display: block;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--accent-color);
}

.subcategory {
    margin-left: 1.5rem;
    margin-top: 1rem;
    padding-left: 1rem;
    border-left: 2px solid var(--glass-border);
}

.subcategory-title {
    font-size: 1.2rem;
    font-weight: 500;
    margin-bottom: 0.75rem;
    color: #cbd5e1;
}

.task {
    display: flex;
    align-items: center;
    padding: 0.75rem;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.03);
    margin-bottom: 0.5rem;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid transparent;
}

.task:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: var(--glass-border);
}

.task.completed {
    opacity: 0.6;
}

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

.checkbox-wrapper {
    position: relative;
    display: inline-block;
    width: 24px;
    height: 24px;
    margin-right: 1rem;
    flex-shrink: 0;
}

.checkbox-wrapper input {
    opacity: 0;
    width: 0;
    height: 0;
}

.checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 24px;
    width: 24px;
    background-color: rgba(255, 255, 255, 0.1);
    border: 2px solid var(--text-secondary);
    border-radius: 6px;
    transition: all 0.3s ease;
}

.task:hover .checkmark {
    border-color: var(--accent-hover);
}

.checkbox-wrapper input:checked ~ .checkmark {
    background-color: var(--success-color);
    border-color: var(--success-color);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
    left: 7px;
    top: 3px;
    width: 6px;
    height: 12px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.checkbox-wrapper input:checked ~ .checkmark:after {
    display: block;
    animation: check-anim 0.2s ease-in-out forwards;
}

@keyframes check-anim {
    0% { height: 0; width: 0; opacity: 0; }
    100% { height: 12px; width: 6px; opacity: 1; }
}

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

::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-gradient-start);
}
::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.2);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.3);
}

@media (max-width: 600px) {
    .app-container {
        padding: 1.5rem;
    }
    h1 {
        font-size: 2rem;
    }
}