/* CalcBay — clean light design system (devbay style) */
:root {
    --bg: #f8fafc;
    --bg-soft: #f1f5f9;
    --text: #0f172a;
    --text-dim: #64748b;
    --text-faint: #94a3b8;
    --card: #ffffff;
    --card-strong: #f8fafc;
    --border: #e2e8f0;
    --border-strong: #cbd5e1;
    --accent-1: #6366f1;
    --accent-2: #4f46e5;
    --accent-3: #818cf8;
    --accent-soft: rgba(99, 102, 241, 0.08);
    --good: #10b981;
    --warn: #f59e0b;
    --bad: #ef4444;
    --radius: 0.625rem;
    --shadow: 0 1px 2px 0 rgba(15, 23, 42, 0.04);
    --shadow-hover: 0 4px 12px 0 rgba(15, 23, 42, 0.08);
    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC",
            "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
}

[data-theme="dark"] {
    --bg: #0f172a;
    --bg-soft: #1e293b;
    --text: #f1f5f9;
    --text-dim: #94a3b8;
    --text-faint: #64748b;
    --card: #1e293b;
    --card-strong: #0f172a;
    --border: #334155;
    --border-strong: #475569;
    --accent-1: #818cf8;
    --accent-2: #a5b4fc;
    --accent-3: #6366f1;
    --accent-soft: rgba(129, 140, 248, 0.14);
    --shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 4px 12px 0 rgba(0, 0, 0, 0.4);
}

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

html { scroll-behavior: smooth; }

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.6;
    transition: background 0.3s ease, color 0.3s ease;
}

.container { width: min(1100px, 92vw); margin: 0 auto; }

/* ---------- header ---------- */
.site-header {
    position: sticky; top: 0; z-index: 50;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); }
.brand-logo { display: flex; }
.brand-name { font-size: 1.25rem; font-weight: 800; letter-spacing: -0.02em; }
.brand-accent {
    color: var(--accent-1);
}
.nav-right { display: flex; align-items: center; gap: 10px; }
.icon-btn {
    display: flex; align-items: center; justify-content: center;
    width: 38px; height: 38px; border-radius: 0.5rem;
    background: var(--card); border: 1px solid var(--border);
    color: var(--text-dim); cursor: pointer; transition: all 0.15s ease;
}
.icon-btn:hover { color: var(--text); border-color: var(--border-strong); background: var(--card-strong); }
.icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }

.lang-switch {
    display: flex; background: var(--card);
    border: 1px solid var(--border); border-radius: 0.5rem; padding: 3px;
}
.lang-btn {
    border: none; background: transparent; color: var(--text-dim);
    font-family: inherit; font-size: 0.8rem; font-weight: 700;
    padding: 5px 12px; border-radius: 0.4rem; cursor: pointer; transition: all 0.15s ease;
}
.lang-btn.active { background: var(--accent-1); color: #fff; }

/* ---------- hero ---------- */
.hero { text-align: center; padding: 72px 0 40px; }
.hero-badge {
    display: inline-block; font-size: 0.78rem; font-weight: 600;
    color: var(--text-dim); background: var(--card);
    border: 1px solid var(--border); border-radius: 9999px;
    padding: 6px 16px; margin-bottom: 20px;
}
.hero-title {
    font-size: clamp(2.2rem, 5.5vw, 3.6rem);
    font-weight: 900; letter-spacing: -0.03em; line-height: 1.15;
}
.grad-text {
    color: var(--accent-1);
}
.hero-sub { max-width: 620px; margin: 18px auto 32px; color: var(--text-dim); font-size: 1.05rem; }
.search-box {
    display: flex; align-items: center; gap: 10px;
    max-width: 480px; margin: 0 auto;
    background: var(--card); border: 1px solid var(--border);
    border-radius: 0.625rem; padding: 12px 20px; color: var(--text-dim);
    box-shadow: var(--shadow);
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.search-box:focus-within { border-color: var(--accent-1); box-shadow: 0 0 0 3px var(--accent-soft); }
.search-box input {
    flex: 1; border: none; outline: none; background: transparent;
    color: var(--text); font-family: inherit; font-size: 1rem;
}
.search-box input::placeholder { color: var(--text-faint); }
.search-empty { text-align: center; color: var(--text-dim); padding: 28px 0; }

/* ---------- calculator grid ---------- */
.cat-section { padding: 28px 0 8px; }
.cat-title {
    display: flex; align-items: center; gap: 10px;
    font-size: 1.15rem; font-weight: 800; margin-bottom: 18px;
}
.cat-icon {
    display: inline-flex; align-items: center; justify-content: center;
    width: 36px; height: 36px; border-radius: 0.5rem;
    background: var(--card); border: 1px solid var(--border);
}
.calc-grid {
    display: grid; gap: 14px;
    grid-template-columns: repeat(auto-fill, minmax(255px, 1fr));
}
.calc-card {
    display: flex; align-items: center; gap: 14px;
    padding: 18px; border-radius: var(--radius);
    background: var(--card); border: 1px solid var(--border);
    box-shadow: var(--shadow);
    text-decoration: none; color: var(--text);
    transition: transform 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}
.calc-card:hover {
    transform: translateY(-2px);
    border-color: var(--border-strong);
    box-shadow: var(--shadow-hover);
}
.calc-card-icon {
    display: flex; align-items: center; justify-content: center;
    width: 46px; height: 46px; flex-shrink: 0; font-size: 1.4rem;
    border-radius: 0.625rem; background: var(--accent-soft);
}
.calc-card-body { flex: 1; min-width: 0; display: flex; flex-direction: column; }
.calc-card-name { font-weight: 700; font-size: 0.98rem; }
.calc-card-desc { color: var(--text-dim); font-size: 0.82rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.calc-card-arrow { color: var(--text-faint); flex-shrink: 0; transition: transform 0.15s ease; }
.calc-card:hover .calc-card-arrow { transform: translateX(3px); color: var(--accent-1); }

/* ---------- calculator page ---------- */
.calc-page { padding: 32px 0 48px; }
.back-link {
    display: inline-block; color: var(--text-dim); text-decoration: none;
    font-size: 0.9rem; font-weight: 600; margin-bottom: 20px;
    transition: color 0.15s ease;
}
.back-link:hover { color: var(--accent-1); }
.calc-head { display: flex; align-items: center; gap: 16px; margin-bottom: 22px; }
.calc-head-icon {
    display: flex; align-items: center; justify-content: center;
    width: 60px; height: 60px; font-size: 1.8rem; flex-shrink: 0;
    border-radius: 0.75rem; background: var(--accent-soft);
}
.calc-head-name { font-size: 1.6rem; font-weight: 800; letter-spacing: -0.02em; }
.calc-head-desc { color: var(--text-dim); font-size: 0.95rem; }

.unit-seg { display: inline-flex; background: var(--card); border: 1px solid var(--border); border-radius: 0.5rem; padding: 3px; margin-bottom: 22px; }
.unit-seg .seg {
    border: none; background: transparent; color: var(--text-dim);
    font-family: inherit; font-size: 0.85rem; font-weight: 600;
    padding: 7px 16px; border-radius: 0.4rem; cursor: pointer; transition: all 0.15s ease;
}
.unit-seg .seg.active { background: var(--accent-1); color: #fff; }

.calc-layout {
    display: grid; gap: 20px;
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: start;
}
@media (max-width: 860px) {
    .calc-layout { grid-template-columns: 1fr; }
}

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

/* fields */
.calc-form { display: flex; flex-direction: column; gap: 16px; }
.field { display: flex; flex-direction: column; gap: 7px; }
.field-label { font-size: 0.85rem; font-weight: 600; color: var(--text-dim); }
.field-control {
    display: flex; align-items: center;
    background: var(--bg-soft); border: 1px solid var(--border);
    border-radius: 0.5rem; overflow: hidden;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.field-control:focus-within { border-color: var(--accent-1); box-shadow: 0 0 0 3px var(--accent-soft); }
.field-control input, .field-control select {
    flex: 1; min-width: 0; padding: 12px 14px;
    border: none; outline: none; background: transparent;
    color: var(--text); font-family: inherit; font-size: 1rem; font-weight: 600;
    -moz-appearance: textfield; appearance: textfield;
}
.field-control select { cursor: pointer; font-weight: 500; }
.field-control select option { background: var(--bg-soft); color: var(--text); }
.field-unit {
    padding-right: 14px; font-size: 0.82rem; color: var(--text-faint); font-weight: 600;
    white-space: nowrap;
}
.chips { display: flex; flex-wrap: wrap; gap: 7px; }
.chip {
    border: 1px solid var(--border); background: var(--card);
    color: var(--text-dim); font-family: inherit; font-size: 0.8rem; font-weight: 600;
    padding: 4px 12px; border-radius: 9999px; cursor: pointer; transition: all 0.15s ease;
}
.chip:hover { border-color: var(--accent-1); color: var(--accent-1); }

/* basic calculator keypad */
.keypad { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.keypad-btn {
    padding: 13px 0; font-size: 1.05rem; font-weight: 700; font-family: inherit;
    border: 1px solid var(--border); border-radius: 0.5rem;
    background: var(--bg-soft); color: var(--text); cursor: pointer;
    transition: all 0.15s ease;
}
.keypad-btn:hover { border-color: var(--accent-1); color: var(--accent-1); }
.keypad-c { background: var(--accent-1); border-color: transparent; color: #fff; }
.keypad-c:hover { color: #fff; background: var(--accent-2); }

/* results */
.calc-results { min-height: 200px; display: flex; flex-direction: column; justify-content: space-between; gap: 16px; position: sticky; top: 84px; }
@media (max-width: 860px) { .calc-results { position: static; } }
.results-placeholder { color: var(--text-faint); font-size: 0.9rem; }
.results-body { display: flex; flex-direction: column; gap: 4px; }
.result-row {
    display: flex; align-items: baseline; justify-content: space-between; gap: 12px;
    padding: 12px 14px; border-radius: 0.5rem;
    background: var(--bg-soft); border: 1px solid var(--border);
    animation: fadeIn 0.25s ease;
}
.result-label { color: var(--text-dim); font-size: 0.86rem; }
.result-value { font-size: 1.12rem; font-weight: 800; letter-spacing: -0.01em; }
.result-value.tone-good { color: var(--good); }
.result-value.tone-warn { color: var(--warn); }
.result-value.tone-bad { color: var(--bad); }
.result-sub { color: var(--text-faint); font-size: 0.76rem; }
.result-notes { color: var(--text-dim); font-size: 0.82rem; padding: 4px 4px 0; }
.results-error { color: var(--bad); font-weight: 600; padding: 8px 0; }
.copy-btn {
    display: inline-flex; align-items: center; gap: 7px;
    align-self: flex-start; padding: 8px 16px; font-size: 0.82rem; font-weight: 700;
    font-family: inherit; border-radius: 0.5rem; cursor: pointer;
    background: transparent; border: 1px solid var(--border);
    color: var(--text-dim); transition: all 0.15s ease;
}
.copy-btn:hover { border-color: var(--accent-1); color: var(--accent-1); }

@keyframes fadeIn { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }

.disclaimer { color: var(--text-faint); font-size: 0.8rem; margin-top: 20px; text-align: center; }

/* ---------- footer ---------- */
.footer-inner { padding: 34px 0 40px; display: flex; flex-direction: column; gap: 14px; }
.footer-tag { color: var(--text-dim); font-size: 0.9rem; }
.footer-links { display: flex; gap: 18px; }
.footer-links a { color: var(--text-dim); text-decoration: none; font-size: 0.9rem; font-weight: 600; transition: color 0.15s ease; }
.footer-links a:hover { color: var(--accent-1); }
.footer-meta { color: var(--text-faint); font-size: 0.8rem; }
.footer-meta a { color: var(--text-dim); }

/* ---------- misc ---------- */
::selection { background: rgba(99, 102, 241, 0.2); }
::-webkit-scrollbar { width: 10px; }
::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 9999px; }
::-webkit-scrollbar-track { background: transparent; }