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

:root {
    --bg-gradient: linear-gradient(135deg, #fdfbfb 0%, #ebedee 100%);
    --primary-color: #6c5ce7;
    --primary-hover: #a29bfe;
    --text-color: #2d3436;
    --secondary-text: #636e72;
    --card-bg: #ffffff;
    --error-color: #ff7675;
    --shadow: 0 10px 20px rgba(0,0,0,0.05);
    --radius: 16px;
}

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

body {
    background: var(--bg-gradient);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    color: var(--text-color);
}

.container {
    background: var(--card-bg);
    width: 100%;
    max-width: 450px;
    padding: 40px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform 0.3s ease;
}

.container:hover {
    transform: translateY(-5px);
}

h1 {
    font-size: 24px;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 10px;
}

p.subtitle {
    font-size: 14px;
    color: var(--secondary-text);
    margin-bottom: 30px;
}

.input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    position: relative;
}

input[type="text"] {
    flex: 1;
    padding: 15px;
    border: 2px solid #dfe6e9;
    border-radius: 12px;
    font-size: 16px;
    outline: none;
    transition: all 0.3s ease;
}

input[type="text"]:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(108, 92, 231, 0.1);
}

button#addTaskButton {
    padding: 15px 25px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 12px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.3s ease, transform 0.1s ease;
}

button#addTaskButton:hover {
    background: var(--primary-hover);
}

button#addTaskButton:active {
    transform: scale(0.95);
}

#taskList {
    display: flex;
    flex-direction: column;
    gap: 15px;
    max-height: 400px;
    overflow-y: auto;
    padding-right: 5px; 
}

#taskList::-webkit-scrollbar {
    width: 6px;
}
#taskList::-webkit-scrollbar-thumb {
    background-color: #dfe6e9;
    border-radius: 10px;
}

.task-item {
    background: #f9f9f9;
    padding: 15px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border: 1px solid #eee;
    animation: slideIn 0.4s ease-out forwards;
    transition: all 0.3s ease;
}

.task-item:hover {
    border-color: var(--primary-color);
    background: #fff;
}

.task-item label {
    flex: 1;
    margin-left: 15px;
    font-size: 16px;
    cursor: pointer;
    word-break: break-all;
    text-align: left;
}

.task-checkbox {
    appearance: none;
    width: 24px;
    height: 24px;
    border: 2px solid #b2bec3;
    border-radius: 50%;
    cursor: pointer;
    position: relative;
    transition: all 0.2s ease;
}

.task-checkbox:checked {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.task-checkbox:checked::after {
    content: '✓';
    color: white;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 14px;
}

.task-item.removing {
    animation: fadeOut 0.4s ease forwards;
}

.alert {
    background-color: #ffeaa7;
    color: #d35400;
    padding: 10px;
    border-radius: 8px;
    margin-top: 10px;
    font-size: 14px;
    display: none; 
    animation: shake 0.3s ease-in-out;
}

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

@keyframes fadeOut {
    to { opacity: 0; transform: scale(0.9); height: 0; margin: 0; padding: 0; }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.empty-state {
    color: #b2bec3;
    margin-top: 20px;
    font-size: 14px;
}

@media (max-width: 450px) {
    .container {
        width: 100%;
        padding: 20px;
    }

    h1 {
        font-size: 20px;
    }

    p.subtitle {
        font-size: 12px;
        margin-bottom: 20px;
    }

    .input-group {
        flex-direction: column; 
        gap: 10px;
    }

    input[type="text"] {
        padding: 12px;
        font-size: 14px;
    }

    button#addTaskButton {
        width: 100%;
        padding: 12px;
        font-size: 14px;
    }

    #taskList {
        max-height: 300px; 
    }

    .task-item {
        padding: 12px;
        font-size: 14px;
    }
}