:root {
    --bg-color: #f0f2f5;
    --container-bg: #ffffff;
    --text-color: #333;
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --border-color: #ddd;
    --strength-very-weak: #e74c3c;
    --strength-weak: #f1c40f;
    --strength-good: #2ecc71;
    --strength-strong: #27ae60;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
    margin: 0;
    box-sizing: border-box;
}

.container {
    background-color: var(--container-bg);
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 8px 30px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 500px;
}

h1 {
    font-size: 1.8em;
    text-align: center;
    margin-top: 0;
    margin-bottom: 25px;
}

.password-area {
    display: flex;
    gap: 10px;
    margin-bottom: 10px;
}

#password {
    flex-grow: 1;
    font-family: "Courier New", Courier, monospace;
    font-size: 1.4em;
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: #f8f9fa;
    min-width: 0; /* flexアイテムの幅が縮小できるようにする */
}

#copy-btn {
    flex-shrink: 0;
    width: 50px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: #fff;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background-color 0.2s, border-color 0.2s;
}
#copy-btn:hover { background-color: #e9ecef; }
#copy-btn.copied {
    background-color: var(--strength-good);
    border-color: var(--strength-strong);
}
#copy-btn.copied svg { stroke: #fff; }


.strength-meter {
    height: 12px;
    width: 100%;
    background-color: #e9ecef;
    border-radius: 6px;
    overflow: hidden;
    margin-bottom: 5px;
}

.strength-bar {
    height: 100%;
    width: 0%;
    border-radius: 6px;
    transition: width 0.3s, background-color 0.3s;
}
#strength-text {
    font-size: 0.9em;
    text-align: right;
    display: block;
    margin-bottom: 20px;
    font-weight: bold;
}

.settings {
    margin-bottom: 25px;
    border-top: 1px solid #eee;
    padding-top: 15px;
}
.settings h2 { margin-top: 0; font-size: 1.2em; }
.setting {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
}
.setting label { flex-grow: 1; cursor: pointer; }
.setting input[type="range"] { flex-grow: 1; }
.setting input[type="checkbox"] { width: 1.2em; height: 1.2em; margin-right: 10px; cursor: pointer; }

#generate-btn {
    width: 100%;
    padding: 15px;
    font-size: 1.2em;
    font-weight: bold;
    color: #fff;
    background-color: var(--primary-color);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s;
}
#generate-btn:hover { background-color: var(--primary-hover); }

.notice {
    text-align: center;
    font-size: 0.8em;
    color: #6c757d;
    margin-top: 20px;
    margin-bottom: 0;
}