body {
    font-family: sans-serif;
    line-height: 1.6;
    background-color: #f4f4f4;
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
}

.container {
    background-color: #fff;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, .1);
    width: 100%;
    max-width: 500px;
}

h1, h2, h3 {
    text-align: center;
    color: #333;
}

/* h3も中央寄せに */
div {
    margin-bottom: 15px;
}

label {
    display: inline-block;
    margin-bottom: 5px;
    font-weight: bold;
    width: 100px;
    box-sizing: border-box;
    vertical-align: top;
}

input[type="text"], select {
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
    width: calc(100% - 110px);
    box-sizing: border-box;
    font-size: 1em;
}

.output input[type="text"] {
    background-color: #eee;
    cursor: default;
}

.error-message {
    color: red;
    font-size: .9em;
    min-height: 1em;
}

.explanation {
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid #eee;
}

.explanation h3 {
    text-align: left;
    color: #333;
    border-bottom: none;
    padding-bottom: 0;
    margin-top: 15px;
    font-size: 1.2em;
}

.explanation h4 {
    color: #444;
    margin-top: 10px;
    margin-bottom: 5px;
    font-size: 1.1em;
}

/* 各進数のタイトル */
.explanation p, .explanation ul {
    font-size: 0.95em;
    color: #555;
}

.explanation ul {
    padding-left: 20px;
}

.explanation li {
    margin-bottom: 8px;
}

.explanation code {
    background-color: #f9f9f9;
    padding: 2px 4px;
    border-radius: 4px;
    font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace;
}

/* ===== theme (skin) overrides — token 駆動（var は /css/theme.css 由来） ===== */
body { background-color: var(--color-bg-base); color: var(--color-fg-primary); }
.container { background-color: var(--color-bg-surface); box-shadow: 0 0 12px rgba(0, 0, 0, 0.4); }
h1, h2, h3 { color: var(--color-fg-primary); }
input[type="text"], select {
    background: var(--color-bg-elevated);
    color: var(--color-fg-primary);
    border-color: var(--color-border-base);
}
.output input[type="text"] { background-color: var(--color-bg-base); color: var(--color-fg-muted); }
.explanation { border-top-color: var(--color-border-base); }
.explanation h3, .explanation h4 { color: var(--color-fg-primary); }
.explanation p, .explanation ul { color: var(--color-fg-muted); }
.explanation code { background-color: var(--color-bg-elevated); color: var(--color-fg-primary); }