:root {
    --primary-color: #4a90e2;
    --background-color: #f4f7f9;
    --text-color: #333;
    --white-color: #ffffff;
    --danger-color: #e24a4a;
    --light-gray-color: #e0e0e0;
    --border-radius: 8px;
    --box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}
.container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 1.5rem;
    background: var(--white-color);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}
header { text-align: center; margin-bottom: 2rem; }
header h1 { color: var(--primary-color); font-weight: 700; }

.task-form { display: flex; gap: 0.5rem; margin-bottom: 2rem; }
.task-input {
    flex-grow: 1;
    padding: 0.75rem;
    border: 1px solid var(--light-gray-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color 0.3s;
}
.task-input:focus { outline: none; border-color: var(--primary-color); }
.add-btn {
    padding: 0.75rem 1.5rem;
    border: none; background-color: var(--primary-color); color: var(--white-color);
    border-radius: var(--border-radius); font-size: 1rem; cursor: pointer; transition: background-color 0.3s;
}
.add-btn:hover { background-color: #357abd; }

#task-list-container {
    padding: 1.5rem; background-color: var(--white-color);
    border-radius: var(--border-radius); border: 1px solid #f0f0f0;
}
.task-list { list-style-type: none; }
.task-item {
    display: flex; align-items: center; padding: 1rem;
    background-color: #fdfdfd; border-bottom: 1px solid var(--light-gray-color);
    transition: background-color 0.3s;
}
.task-item:last-child { border-bottom: none; }
.task-item:hover { background-color: #f9f9f9; }

.task-text { flex-grow: 1; cursor: pointer; }
.task-text:focus {
    outline: none; background-color: #e7f1ff; padding: 0.2rem; border-radius: 4px;
}

.task-actions button {
    border: none; background: none; cursor: pointer; padding: 0.5rem; font-size: 1.2rem; margin-left: 0.5rem;
}
.delete-btn { color: var(--danger-color); transition: color 0.3s; }
.delete-btn:hover { color: #c0392b; }

.export-buttons {
    display: flex; justify-content: center; gap: 1rem; margin-top: 2rem;
}
.export-btn {
    padding: 0.75rem 1.5rem; border: 1px solid var(--primary-color);
    background-color: var(--white-color); color: var(--primary-color);
    border-radius: var(--border-radius); cursor: pointer; transition: background-color 0.3s, color 0.3s;
}
.export-btn:hover { background-color: var(--primary-color); color: var(--white-color); }

.support-buttons {
    display: flex; justify-content: center; gap: 1rem;
    margin-top: 1.5rem; padding-top: 1.5rem; border-top: 1px solid var(--light-gray-color);
}
.support-btn {
    padding: 0.75rem 1.5rem; border: 1px solid #6c757d; background-color: var(--white-color);
    color: #6c757d; border-radius: var(--border-radius); cursor: pointer; text-decoration: none;
    text-align: center; transition: background-color 0.3s, color 0.3s;
}
.support-btn:hover { background-color: #6c757d; color: var(--white-color); }

@media (max-width: 600px) {
    .container { margin: 1rem; padding: 1rem; }
    .task-form { flex-direction: column; }
    .add-btn { width: 100%; }
    .task-item { flex-direction: column; align-items: flex-start; gap: 0.5rem; }
    .task-actions { width: 100%; text-align: right; }
    .export-buttons, .support-buttons { flex-direction: column; }
}