/* ============================================
   Ideal Weight Calculator Styles
   Clean, clinical, trustworthy health aesthetic
============================================ */
:root {
    --bg: #0a0f1e;
    --surface: rgba(255, 255, 255, 0.04);
    --border: rgba(255, 255, 255, 0.08);
    --text: #f1f5f9;
    --text-muted: #64748b;
    --accent: #10b981;
    /* Health green */
    --accent-glow: rgba(16, 185, 129, 0.25);
    --radius: 14px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Outfit', sans-serif;
}

body {
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    background-image:
        radial-gradient(ellipse at 20% 20%, rgba(16, 185, 129, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(6, 182, 212, 0.06) 0%, transparent 50%);
}

.tool-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--border);
}

.back-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.back-link:hover {
    color: var(--text);
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    font-weight: 700;
    color: var(--accent);
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 2rem;
}

.tool-header {
    text-align: center;
    margin-bottom: 2.5rem;
}

.header-badge {
    display: inline-block;
    padding: 0.35rem 1rem;
    background: rgba(16, 185, 129, 0.12);
    color: var(--accent);
    border: 1px solid rgba(16, 185, 129, 0.25);
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    margin-bottom: 1rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    background: linear-gradient(135deg, #f1f5f9, var(--accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.tool-header p {
    color: var(--text-muted);
    font-size: 1rem;
    max-width: 540px;
    margin: 0 auto;
    line-height: 1.65;
}

.tool-layout {
    display: grid;
    grid-template-columns: 380px 1fr;
    gap: 2rem;
    align-items: start;
}

/* Input Panel */
.input-panel {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.unit-toggle-group {
    display: flex;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 4px;
}

.unit-btn {
    flex: 1;
    padding: 0.5rem;
    background: transparent;
    border: none;
    color: var(--text-muted);
    border-radius: 7px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.85rem;
    transition: all 0.2s;
}

.unit-btn.active {
    background: var(--accent);
    color: white;
}

.form-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.form-group label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.gender-toggle {
    display: flex;
    gap: 0.75rem;
}

.gender-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-muted);
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s;
}

.gender-btn:hover {
    color: var(--text);
}

.gender-btn.active {
    border-color: var(--accent);
    color: var(--accent);
    background: rgba(16, 185, 129, 0.08);
}

.input-with-unit {
    display: flex;
    align-items: center;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
    transition: border-color 0.2s;
}

.input-with-unit:focus-within {
    border-color: var(--accent);
}

.input-with-unit input {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text);
    padding: 0.75rem 1rem;
    font-size: 1rem;
    outline: none;
}

.unit-badge {
    padding: 0.75rem 1rem;
    background: rgba(255, 255, 255, 0.04);
    color: var(--text-muted);
    font-weight: 700;
    font-size: 0.85rem;
    border-left: 1px solid var(--border);
}

.dual-input {
    display: flex;
    gap: 0.5rem;
}

.dual-input .input-with-unit {
    flex: 1;
}

.calc-btn {
    padding: 1rem;
    background: linear-gradient(135deg, var(--accent), #06b6d4);
    border: none;
    border-radius: 10px;
    color: white;
    font-size: 1rem;
    font-weight: 700;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    transition: all 0.2s;
    box-shadow: 0 8px 20px var(--accent-glow);
}

.calc-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 14px 28px var(--accent-glow);
}

/* Results */
.results-panel {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.results-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.formula-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

.formula-card.is-best {
    border-color: var(--accent);
    box-shadow: 0 0 20px rgba(16, 185, 129, 0.15);
}

.formula-name {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.formula-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent);
    line-height: 1;
    margin-bottom: 0.25rem;
}

.formula-unit {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.formula-range {
    margin-top: 0.75rem;
    font-size: 0.8rem;
    color: var(--text-muted);
    background: rgba(0, 0, 0, 0.2);
    padding: 0.4rem 0.75rem;
    border-radius: 6px;
}

.best-badge {
    display: inline-block;
    margin-top: 0.5rem;
    padding: 0.2rem 0.6rem;
    background: rgba(16, 185, 129, 0.2);
    color: var(--accent);
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 700;
}

.note-card {
    display: flex;
    gap: 1rem;
    background: rgba(6, 182, 212, 0.06);
    border: 1px solid rgba(6, 182, 212, 0.15);
    border-radius: 10px;
    padding: 1rem 1.25rem;
}

.note-card i {
    color: #06b6d4;
    margin-top: 2px;
    flex-shrink: 0;
}

.note-card p {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.6;
}

.note-card strong {
    color: var(--text);
}

@media (max-width: 900px) {
    .tool-layout {
        grid-template-columns: 1fr;
    }

    h1 {
        font-size: 2rem;
    }

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

@media (max-width: 500px) {
    .results-grid {
        grid-template-columns: 1fr;
    }
}