:root {
    --primary-color: #4a90e2;
    --background-color: #ffffff;
    --text-color: #333333;
    --border-color: #e0e0e0;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --primary-color: #64b5f6;
    --background-color: #1a1a1a;
    --text-color: #ffffff;
    --border-color: #404040;
    --shadow-color: rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
}

.theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-color);
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
    transition: background-color 0.3s;
}

.theme-toggle:hover {
    background-color: var(--shadow-color);
}

.memo-input {
    margin-bottom: 30px;
}

textarea {
    width: 100%;
    height: 150px;
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    resize: vertical;
    font-size: 1rem;
    background-color: var(--background-color);
    color: var(--text-color);
    margin-bottom: 15px;
    transition: border-color 0.3s;
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.save-button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: transform 0.2s, background-color 0.3s;
}

.save-button:hover {
    transform: translateY(-2px);
    background-color: var(--primary-color);
    opacity: 0.9;
}

.memo-list {
    display: grid;
    gap: 20px;
}

.memo-item {
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
    position: relative;
    box-shadow: 0 2px 8px var(--shadow-color);
    transition: transform 0.2s;
}

.memo-item:hover {
    transform: translateY(-2px);
}

.memo-text {
    margin-bottom: 15px;
    line-height: 1.5;
}

.memo-date {
    font-size: 0.85rem;
    color: #888;
}

.delete-button {
    position: absolute;
    top: 10px;
    right: 10px;
    background: none;
    border: none;
    color: #ff4444;
    cursor: pointer;
    padding: 5px;
    font-size: 1.1rem;
    transition: transform 0.2s;
}

.delete-button:hover {
    transform: scale(1.1);
}

@media (max-width: 600px) {
    .container {
        padding: 15px;
    }

    h1 {
        font-size: 2rem;
    }

    .memo-item {
        padding: 15px;
    }
}