@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=Vazirmatn:wght@400;500;600;700;800&display=swap');

:root {
    --bg: #f4f7fb;
    --card: rgba(255, 255, 255, .88);
    --input: rgba(255, 255, 255, .55);
    --text: #172033;
    --muted: #718096;
    --primary: #5b5cf0;
    --primary-dark: #4546d5;
    --border: #e4e8f0;
    --danger: #e5484d;
    --shadow: 0 24px 70px rgba(40, 50, 90, .12);
}

body.dark {
    --bg: #0e1220;
    --card: rgba(24, 29, 46, .92);
    --input: rgba(0, 0, 0, .12);
    --text: #f3f5fb;
    --muted: #a5aec2;
    --border: #30384d;
    --shadow: 0 24px 70px rgba(0, 0, 0, .32);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    margin: 0;
    min-height: 100vh;
    font-family: "Vazirmatn", "Inter", Tahoma, sans-serif;
    color: var(--text);
    background:
        radial-gradient(circle at 10% 10%, rgba(91, 92, 240, .16), transparent 30%),
        radial-gradient(circle at 90% 80%, rgba(0, 194, 255, .10), transparent 28%),
        var(--bg);
    transition: background .3s ease, color .3s ease;
}

body[data-lang="en"] { font-family: "Inter", "Vazirmatn", sans-serif; }

button, input { font: inherit; }

button { -webkit-tap-highlight-color: transparent; }

.app {
    width: min(920px, calc(100% - 32px));
    margin: 0 auto;
    padding: 42px 0 24px;
}

.hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    margin-bottom: 24px;
}

.eyebrow {
    color: var(--primary);
    font-size: .75rem;
    font-weight: 800;
    letter-spacing: .12em;
}

h1 {
    margin: 6px 0;
    font-size: clamp(2rem, 5vw, 3.3rem);
    letter-spacing: -.04em;
}

.hero p {
    color: var(--muted);
    margin: 0;
    line-height: 1.8;
}

.header-actions {
    display: flex;
    gap: 10px;
    direction: ltr;
}

.language-toggle,
.theme-toggle {
    width: 48px;
    height: 48px;
    border: 1px solid var(--border);
    border-radius: 15px;
    background: var(--card);
    color: var(--text);
    cursor: pointer;
    box-shadow: 0 8px 25px rgba(0,0,0,.06);
    transition: transform .2s ease, border-color .2s ease;
}

.language-toggle { font-size: .78rem; font-weight: 800; }
.theme-toggle { font-size: 1.3rem; }

.language-toggle:hover,
.theme-toggle:hover {
    transform: translateY(-2px);
    border-color: var(--primary);
}

.calculator-card {
    padding: clamp(22px, 5vw, 40px);
    border: 1px solid var(--border);
    border-radius: 28px;
    background: var(--card);
    box-shadow: var(--shadow);
    backdrop-filter: blur(18px);
}

.fields {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 18px;
}

.field label {
    display: block;
    margin-bottom: 9px;
    font-weight: 700;
}

.input-wrap {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 0 15px;
    border: 1px solid var(--border);
    border-radius: 15px;
    background: var(--input);
    transition: .2s ease;
}

.input-wrap:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(91,92,240,.12);
}

input {
    width: 100%;
    min-width: 0;
    border: 0;
    outline: 0;
    padding: 15px 0;
    background: transparent;
    color: var(--text);
    font-weight: 600;
}

.input-wrap span {
    color: var(--muted);
    font-weight: 700;
    direction: ltr;
}

.hint, .error {
    display: block;
    margin-top: 6px;
    font-size: .76rem;
    line-height: 1.5;
}

.hint { color: var(--muted); }
.error { color: var(--danger); min-height: 18px; }

.actions {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 12px;
    margin-top: 10px;
}

.primary-btn, .reset-btn {
    min-height: 52px;
    border-radius: 15px;
    cursor: pointer;
    font-weight: 800;
    transition: transform .2s ease, box-shadow .2s ease;
}

.primary-btn {
    border: 0;
    color: #fff;
    background: linear-gradient(135deg, var(--primary), #7b5cff);
    box-shadow: 0 12px 25px rgba(91,92,240,.25);
}

.reset-btn {
    padding: 0 24px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text);
}

.primary-btn:hover, .reset-btn:hover { transform: translateY(-2px); }

.result {
    margin-top: 28px;
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: 22px;
    background: rgba(91,92,240,.05);
    animation: reveal .4s ease;
}

.hidden { display: none; }

.result-top {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.result-label {
    display: block;
    color: var(--muted);
    font-size: .9rem;
}

#bmiValue {
    display: block;
    margin-top: 3px;
    font-size: 3rem;
    line-height: 1.1;
    direction: ltr;
}

.status-badge {
    padding: 9px 15px;
    border-radius: 999px;
    font-weight: 800;
    background: #e8eaff;
    color: var(--primary-dark);
}

.scale { margin-top: 28px; }

.scale-track {
    position: relative;
    height: 12px;
    border-radius: 999px;
    background: linear-gradient(90deg, #55a6ff 0 25%, #43c985 25% 50%, #ffbd5a 50% 75%, #ee6262 75% 100%);
}

.marker {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    border: 3px solid var(--card);
    border-radius: 50%;
    background: #172033;
    transform: translate(-50%, -50%);
    box-shadow: 0 3px 10px rgba(0,0,0,.2);
    transition: left .5s ease;
}

.scale-labels {
    display: flex;
    justify-content: space-between;
    gap: 8px;
    margin-top: 10px;
    color: var(--muted);
    font-size: .72rem;
}

.result-message {
    margin: 20px 0 0;
    color: var(--muted);
    line-height: 1.8;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    margin-top: 16px;
}

.info-grid article {
    padding: 18px 12px;
    border: 1px solid var(--border);
    border-radius: 18px;
    background: var(--card);
    text-align: center;
}

.info-grid strong, .info-grid span { display: block; }
.info-grid strong { font-size: .9rem; direction: ltr; }
.info-grid span { margin-top: 5px; color: var(--muted); font-size: .75rem; }

footer {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    padding: 22px 4px 0;
    color: var(--muted);
    font-size: .75rem;
}

@keyframes reveal {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 650px) {
    .app { padding-top: 25px; }
    .hero { align-items: flex-start; }
    .header-actions { flex-shrink: 0; }
    .fields, .info-grid { grid-template-columns: 1fr; }
    .actions { grid-template-columns: 1fr; }
    .reset-btn { min-height: 48px; }
    .scale-labels { font-size: .65rem; }
    footer { flex-direction: column; text-align: center; }
}

@media (max-width: 430px) {
    .app { width: min(100% - 20px, 920px); }
    .hero { gap: 12px; }
    .theme-toggle, .language-toggle { width: 42px; height: 42px; border-radius: 13px; }
    .header-actions { gap: 6px; }
}