:root {
    --primary-color: #6366f1;
    --background-color: #0f172a;
    --card-background: #1e293b;
    --text-color: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --danger-color: #ef4444;
    --border-radius: 12px;
    --shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    justify-content: center;
    padding: 2rem 1rem;
    min-height: 100vh;
    position: relative;
    z-index: 1;
    overflow-x: hidden;
}

.grid-background {
    position: fixed;
    top: 50%;
    left: 50%;
    width: 200vw;
    height: 200vh;
    background-image: 
        linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
    background-size: 40px 40px;
    transform: translate(-50%, -20%) perspective(1000px) rotateX(75deg);
    z-index: -2;
    pointer-events: none;
}

#cursor-glow {
    position: fixed;
    top: -150px;
    left: -150px;
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.15) 0%, transparent 60%);
    border-radius: 50%;
    pointer-events: none;
    z-index: -1;
    transition: opacity 0.3s ease;
    opacity: 1;
    will-change: transform;
}

#cursor-glow.hidden {
    opacity: 0;
}

.app-container {
    width: 95%;
    max-width: 550px;
    background-color: var(--card-background);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.app-header {
    background-color: var(--primary-color);
    color: white;
    padding: 2rem 1.5rem;
    text-align: center;
}

.app-header h1 {
    font-size: 1.8rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.app-main {
    padding: 1.5rem;
}

.task-input-container {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

#task-input {
    flex-grow: 1;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
    background-color: var(--card-background);
    color: var(--text-color);
}

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

#add-task-btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    padding: 0 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

#add-task-btn:hover {
    background-color: #357abd;
}

.task-filters {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

.filter-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    padding: 0.5rem 0.75rem;
    border-radius: var(--border-radius);
    transition: all 0.2s;
}

.filter-btn:hover {
    background-color: var(--background-color);
    color: var(--text-color);
}

.filter-btn.active {
    background-color: var(--primary-color);
    color: white;
}

.task-list {
    list-style: none;
}

.task-item {
    display: flex;
    align-items: center;
    padding: 1.1rem 1.25rem;
    gap: 0.8rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 0.8rem;
    background-color: var(--card-background);

    transition: translate 0.3s ease-out, transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275), box-shadow 0.4s ease, border-color 0.4s ease, opacity 0.3s ease;
    will-change: transform, translate, opacity;
    animation: float-zero-gravity 5s ease-in-out infinite;
    translate: 0px 0px;
    position: relative;
    transform-origin: center;
}

.task-item.entering {
    animation: task-entry 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards !important;
}

.task-item.exiting {
    animation: task-exit 0.3s ease-in forwards !important;
    pointer-events: none;
}

@keyframes task-entry {
    0% { opacity: 0; transform: translateY(20px) scale(0.95); }
    100% { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes task-exit {
    0% { opacity: 1; transform: scale(1); }
    100% { opacity: 0; transform: scale(0.9) translateY(-10px); }
}

@keyframes float-zero-gravity {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    33%      { transform: translateY(-5px) rotate(0.8deg); }
    66%      { transform: translateY(-3px) rotate(-0.8deg); }
}

.task-item:hover {
    animation: none;
    transform: translateY(-8px) rotate(1.5deg) scale(1.02);
    box-shadow: 0 15px 30px -8px rgba(0, 0, 0, 0.6);
    border-color: var(--primary-color);
    z-index: 10;
}

.task-checkbox-container {
    display: flex;
    align-items: center;
}

.task-checkbox {
    width: 1.2rem;
    height: 1.2rem;
    cursor: pointer;
}

.task-text {
    flex-grow: 1;
    font-size: 1rem;
    word-break: break-word;
}

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

.delete-btn {
    background-color: transparent;
    color: var(--danger-color);
    border: 1px solid transparent;
    border-radius: var(--border-radius);
    padding: 0.4rem 0.8rem;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.delete-btn:hover {
    background-color: #fdf0ef;
    border-color: var(--danger-color);
}

.empty-state {
    text-align: center;
    color: var(--text-muted);
    padding: 1rem;
}