:root {
    color-scheme: light;
    --bg: #f3f5f8;
    --surface: #ffffff;
    --surface-soft: #eef3f7;
    --line: #cfd7df;
    --text: #17202a;
    --muted: #647282;
    --primary: #0f6a7a;
    --primary-dark: #084b58;
    --accent: #d84545;
    --ok: #1f8a5b;
    --warn: #b05f00;
    --shadow: 0 16px 40px rgba(16, 28, 42, 0.12);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    background:
        linear-gradient(135deg, rgba(15, 106, 122, 0.10), transparent 34%),
        linear-gradient(315deg, rgba(216, 69, 69, 0.08), transparent 30%),
        var(--bg);
    color: var(--text);
    font-family: "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", system-ui, sans-serif;
    line-height: 1.6;
}

button,
input {
    font: inherit;
}

button {
    min-height: 44px;
    border: 1px solid transparent;
    border-radius: 8px;
    cursor: pointer;
}

button:focus-visible,
input:focus-visible {
    outline: 3px solid rgba(15, 106, 122, 0.28);
    outline-offset: 2px;
}

.app-shell {
    width: min(1120px, 100%);
    margin: 0 auto;
    padding: 24px;
}

.topbar {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 16px;
    padding: 18px 0 20px;
}

.eyebrow {
    margin: 0 0 4px;
    color: var(--primary);
    font-size: 0.88rem;
    font-weight: 700;
}

h1 {
    margin: 0;
    font-size: clamp(1.8rem, 3vw, 3rem);
    line-height: 1.18;
    letter-spacing: 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 10px;
    margin-bottom: 14px;
}

.stat-box {
    background: rgba(255, 255, 255, 0.78);
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 12px;
}

.stat-label {
    display: block;
    color: var(--muted);
    font-size: 0.82rem;
}

.stat-box strong {
    display: block;
    font-size: 1.55rem;
    line-height: 1.2;
}

.controls {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 16px;
}

.segmented {
    display: grid;
    grid-template-columns: repeat(4, minmax(74px, 1fr));
    gap: 4px;
    padding: 4px;
    background: #dce5eb;
    border-radius: 8px;
    width: min(520px, 100%);
}

.segment {
    background: transparent;
    color: var(--muted);
    border-radius: 6px;
    padding: 0 10px;
}

.segment.is-active {
    background: var(--surface);
    color: var(--primary-dark);
    box-shadow: 0 2px 8px rgba(15, 106, 122, 0.12);
    font-weight: 700;
}

.toggle {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--muted);
    white-space: nowrap;
    user-select: none;
}

.toggle input {
    width: 20px;
    height: 20px;
    accent-color: var(--primary);
}

.study-card {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 24px;
}

.card-meta,
.subject-row,
.action-row,
.master-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.card-meta {
    color: var(--muted);
    font-size: 0.9rem;
    margin-bottom: 16px;
}

.card-meta a,
.data-note a {
    color: var(--primary-dark);
    font-weight: 700;
    text-decoration: underline;
    text-underline-offset: 3px;
}

.subject-row {
    margin-bottom: 14px;
}

.subject-pill {
    display: inline-flex;
    align-items: center;
    min-height: 34px;
    padding: 4px 12px;
    background: var(--surface-soft);
    border: 1px solid var(--line);
    border-radius: 999px;
    color: var(--primary-dark);
    font-weight: 700;
}

.icon-button {
    width: 44px;
    padding: 0;
    background: var(--surface-soft);
    border-color: var(--line);
    color: var(--warn);
    font-size: 1.3rem;
}

.icon-button.is-active {
    background: #fff1c4;
    border-color: #e2bd42;
}

#question-text {
    margin: 0 0 18px;
    font-size: clamp(1.2rem, 2.2vw, 1.65rem);
    line-height: 1.55;
    letter-spacing: 0;
}

.choices {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 10px;
}

.choice-button {
    min-height: 64px;
    padding: 12px;
    background: #f8fafc;
    border-color: var(--line);
    color: var(--text);
    text-align: left;
}

.choice-button:hover {
    border-color: var(--primary);
}

.choice-button.is-selected {
    border-color: var(--primary);
    background: #e8f6f8;
}

.choice-button.is-correct {
    border-color: var(--ok);
    background: #e8f7ef;
}

.choice-button.is-wrong {
    border-color: var(--accent);
    background: #fdecec;
}

.answer-panel {
    margin: 18px 0 0;
    padding: 16px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: #f7f9fb;
}

.answer-line {
    margin: 0 0 8px;
    color: var(--primary-dark);
    font-weight: 700;
}

.answer-panel p:last-child {
    margin-bottom: 0;
}

.action-row {
    margin-top: 18px;
}

.primary-button,
.secondary-button,
.ghost-button {
    padding: 0 16px;
    font-weight: 700;
}

.primary-button {
    background: var(--primary);
    color: #ffffff;
}

.primary-button:hover {
    background: var(--primary-dark);
}

.secondary-button {
    background: var(--surface-soft);
    border-color: var(--line);
    color: var(--text);
}

.ghost-button {
    background: transparent;
    border-color: var(--line);
    color: var(--muted);
}

.ghost-button:hover,
.secondary-button:hover {
    border-color: var(--primary);
    color: var(--primary-dark);
}

.master-row {
    justify-content: flex-end;
    margin-top: 10px;
}

.ghost-button.is-active {
    border-color: var(--ok);
    color: var(--ok);
    background: #e8f7ef;
}

.data-note {
    margin-top: 18px;
    padding: 16px 0 0;
    color: var(--muted);
}

.data-note h2 {
    margin: 0 0 6px;
    color: var(--text);
    font-size: 1rem;
}

.data-note p {
    margin: 0;
}

.result-dialog {
    position: fixed;
    inset: 0;
    z-index: 20;
    display: grid;
    place-items: center;
    padding: 18px;
    background: rgba(10, 19, 29, 0.44);
}

.result-dialog[hidden] {
    display: none;
}

.result-card {
    width: min(620px, 100%);
    max-height: min(760px, calc(100vh - 36px));
    overflow: auto;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 8px;
    box-shadow: 0 26px 80px rgba(10, 19, 29, 0.30);
    padding: 24px;
}

.result-card h2 {
    margin: 0;
    font-size: clamp(1.8rem, 6vw, 3rem);
    line-height: 1.15;
}

.result-lead {
    margin: 10px 0 18px;
    color: var(--muted);
    font-size: 1.05rem;
}

.result-score-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px;
}

.result-score-grid div {
    background: var(--surface-soft);
    border: 1px solid var(--line);
    border-radius: 8px;
    padding: 12px;
}

.result-score-grid span {
    display: block;
    color: var(--muted);
    font-size: 0.82rem;
}

.result-score-grid strong {
    display: block;
    font-size: 1.45rem;
}

.result-review {
    margin-top: 18px;
}

.result-review h3 {
    margin: 0 0 8px;
    font-size: 1rem;
}

.result-review ul {
    display: grid;
    gap: 8px;
    margin: 0;
    padding: 0;
    list-style: none;
}

.result-review li {
    padding: 10px 12px;
    background: #f8fafc;
    border: 1px solid var(--line);
    border-radius: 8px;
}

.result-actions {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
    margin-top: 18px;
}

code {
    background: rgba(15, 106, 122, 0.10);
    border-radius: 4px;
    padding: 2px 5px;
}

@media (max-width: 720px) {
    .app-shell {
        padding: 14px;
    }

    .topbar {
        flex-direction: column;
    }

    .stats-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .controls {
        align-items: stretch;
        flex-direction: column;
    }

    .segmented {
        width: 100%;
    }

    .study-card {
        padding: 16px;
    }

    .choices {
        grid-template-columns: 1fr;
    }

    .action-row {
        display: grid;
        grid-template-columns: 1fr 1.3fr 1fr;
    }

    .result-score-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 430px) {
    .segmented {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .action-row {
        grid-template-columns: 1fr;
    }

    .result-actions {
        display: grid;
        grid-template-columns: 1fr;
    }
}