:root {
    --bg: #f7f9fc;
    --card: #ffffff;
    --text: #2b3440;
    --muted: #6b7684;
    --primary: #5b8def;
    --primary-dark: #3f6fd0;
    --accent: #f0a868;
    --border: #e6ebf2;
    --good: #4caf7d;
    --shadow: 0 4px 20px rgba(60, 80, 120, 0.08);
    --radius: 14px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    padding: 0 0 3rem;
}

.site-header {
    max-width: 820px;
    margin: 0 auto;
    padding: 1.5rem 1rem 0.5rem;
    display: flex;
    align-items: baseline;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.brand {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text);
    text-decoration: none;
    letter-spacing: -0.5px;
}
.brand-accent { color: var(--primary); }
.brand-tag {
    font-size: 0.85rem;
    color: var(--muted);
}

.container {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 1rem;
}

.hero { text-align: center; padding: 1.5rem 0 1rem; }
.hero h1 { font-size: 1.85rem; color: var(--text); }
.subtitle { color: var(--muted); margin-top: 0.5rem; font-size: 0.95rem; }

.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.25rem;
    box-shadow: var(--shadow);
}
.card h2 { font-size: 1.15rem; margin-bottom: 1rem; }

.tabs { display: flex; gap: 0.5rem; margin-bottom: 1.25rem; flex-wrap: wrap; }
.tab {
    flex: 1;
    min-width: 200px;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--bg);
    color: var(--muted);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.2s;
}
.tab.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

.input-row { margin-bottom: 1.25rem; }
.input-row label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.4rem;
    font-size: 0.92rem;
}
.input-row input[type="time"] {
    width: 100%;
    padding: 0.7rem 0.9rem;
    border: 1px solid var(--border);
    border-radius: 10px;
    font-size: 1.1rem;
    color: var(--text);
    background: #fff;
}
.help { display: block; font-size: 0.8rem; color: var(--muted); margin-top: 0.35rem; }

.cycle-stepper {
    display: flex;
    align-items: center;
    gap: 0;
    border: 1px solid var(--border);
    border-radius: 10px;
    width: fit-content;
    overflow: hidden;
}
.stepper-btn {
    width: 44px; height: 44px;
    border: none;
    background: var(--bg);
    font-size: 1.4rem;
    color: var(--primary);
    cursor: pointer;
}
.stepper-btn:hover { background: var(--border); }
.cycle-stepper input {
    width: 60px; height: 44px;
    border: none;
    text-align: center;
    font-size: 1.1rem;
    font-weight: 600;
    border-left: 1px solid var(--border);
    border-right: 1px solid var(--border);
}

.primary-btn {
    width: 100%;
    padding: 0.85rem;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}
.primary-btn:hover { background: var(--primary-dark); }

.result-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 0.75rem;
}
.result-item {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 0.9rem;
    text-align: center;
}
.result-item.best {
    border-color: var(--good);
    background: #eefaf3;
}
.result-item .cycles {
    font-size: 0.78rem;
    color: var(--muted);
}
.result-item .time {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--text);
    margin: 0.2rem 0;
}
.result-item.best .time { color: var(--good); }
.result-item .dur { font-size: 0.78rem; color: var(--muted); }
.result-item.best .best-tag {
    display: inline-block;
    font-size: 0.7rem;
    background: var(--good);
    color: #fff;
    padding: 1px 8px;
    border-radius: 10px;
    margin-top: 4px;
}

.disclaimer {
    margin-top: 1rem;
    padding: 0.75rem;
    background: #fff8ec;
    border-left: 3px solid var(--accent);
    border-radius: 8px;
    font-size: 0.82rem;
    color: #8a6d3b;
}

.explain strong { color: var(--primary-dark); }
.tips { list-style: none; margin-top: 0.75rem; }
.tips li { padding: 0.35rem 0; font-size: 0.92rem; }

.site-footer {
    max-width: 720px;
    margin: 2rem auto 0;
    padding: 1.5rem 1rem 0;
    text-align: center;
    font-size: 0.82rem;
    color: var(--muted);
}
.footer-links a {
    color: var(--primary);
    text-decoration: none;
    margin: 0 0.3rem;
}

@media (max-width: 480px) {
    .hero h1 { font-size: 1.5rem; }
    .card { padding: 1.1rem; }
}