@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* ─── Design Tokens ─────────────────────────────────── */
:root {
    --primary: #3b82f6;
    --primary-light: #eff6ff;
    --primary-hover: #2563eb;
    --accent: #06b6d4;
    --success: #10b981;
    --warning: #f59e0b;

    --bg: #f8fafc;
    --surface: #ffffff;
    --surface-2: #f1f5f9;
    --border: #e2e8f0;
    --border-focus: #3b82f6;

    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;

    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, .07);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, .08);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, .10);
    --transition: 0.18s ease;
}

/* ─── Reset ─────────────────────────────────────────── */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

button {
    cursor: pointer;
    font-family: inherit;
}

input {
    font-family: inherit;
}

/* ─── Header ─────────────────────────────────────────── */
.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 0 24px;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header-inner {
    max-width: 1100px;
    margin: 0 auto;
    height: 60px;
    display: flex;
    align-items: center;
    gap: 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    white-space: nowrap;
}

.logo-icon {
    font-size: 1.3rem;
}

/* ─── Search Bar ─────────────────────────────────────── */
.search-wrap {
    flex: 1;
    position: relative;
    max-width: 420px;
}

.search-icon {
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-size: 0.9rem;
    pointer-events: none;
}

#globalSearch {
    width: 100%;
    padding: 8px 12px 8px 36px;
    border: 1.5px solid var(--border);
    border-radius: 20px;
    background: var(--surface-2);
    font-size: 0.9rem;
    color: var(--text-primary);
    transition: border-color var(--transition), box-shadow var(--transition);
    outline: none;
}

#globalSearch:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, .15);
    background: var(--surface);
}

.search-results {
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    right: 0;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    z-index: 200;
    overflow: hidden;
    display: none;
}

.search-results.visible {
    display: block;
}

.search-item {
    padding: 10px 16px;
    cursor: pointer;
    font-size: 0.875rem;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: background var(--transition);
}

.search-item:hover {
    background: var(--primary-light);
}

.search-item .si-cat {
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* ─── Layout ─────────────────────────────────────────── */
.main-wrap {
    max-width: 1100px;
    margin: 0 auto;
    padding: 28px 20px 60px;
}

/* ─── Category Tabs ──────────────────────────────────── */
.cat-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 28px;
}

.cat-tab {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 16px;
    border: 1.5px solid var(--border);
    border-radius: 20px;
    background: var(--surface);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all var(--transition);
}

.cat-tab:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-light);
}

.cat-tab.active {
    background: var(--primary);
    border-color: var(--primary);
    color: #fff;
    box-shadow: 0 2px 8px rgba(59, 130, 246, .30);
}

.cat-tab .tab-emoji {
    font-size: 1rem;
}

/* ─── Converter Panel ────────────────────────────────── */
.converter-panel {
    display: none;
}

.converter-panel.active {
    display: block;
}

.panel-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
}

.panel-icon {
    font-size: 2rem;
}

.panel-title {
    font-size: 1.3rem;
    font-weight: 700;
}

.panel-subtitle {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 2px;
}

/* ─── Unit Grid ──────────────────────────────────────── */
.unit-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 14px;
}

.unit-group-divider {
    grid-column: 1 / -1;
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 8px 0 2px;
}

.unit-group-divider::before,
.unit-group-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
}

.unit-group-divider span {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    white-space: nowrap;
}

.unit-card {
    background: var(--surface);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-md);
    padding: 16px 18px;
    transition: border-color var(--transition), box-shadow var(--transition);
    position: relative;
}

.unit-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
}

.unit-card.source-active {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, .12);
}

.unit-label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
}

.unit-name {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.unit-input-wrap {
    position: relative;
}

.unit-value {
    width: 100%;
    padding: 10px 44px 10px 14px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    background: var(--surface-2);
    transition: all var(--transition);
    outline: none;
}

.unit-value:focus {
    border-color: var(--border-focus);
    background: var(--surface);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, .12);
}

.copy-btn {
    position: absolute;
    right: 8px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.85rem;
    padding: 4px;
    border-radius: 4px;
    transition: color var(--transition), background var(--transition);
    line-height: 1;
}

.copy-btn:hover {
    color: var(--primary);
    background: var(--primary-light);
}

.copy-btn.copied {
    color: var(--success);
}

/* ─── History ────────────────────────────────────────── */
.history-section {
    margin-top: 36px;
    padding-top: 24px;
    border-top: 1px solid var(--border);
}

.history-title {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.history-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.history-chip {
    padding: 5px 12px;
    border-radius: 20px;
    background: var(--surface-2);
    border: 1px solid var(--border);
    font-size: 0.8rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}

.history-chip:hover {
    background: var(--primary-light);
    border-color: var(--primary);
    color: var(--primary);
}

.history-clear {
    background: none;
    border: none;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-left: auto;
    text-decoration: underline;
    cursor: pointer;
}

.history-clear:hover {
    color: #ef4444;
}

/* ─── Info Box ───────────────────────────────────────── */
.info-box {
    margin-top: 20px;
    padding: 14px 18px;
    background: #fffbeb;
    border: 1px solid #fcd34d;
    border-radius: var(--radius-md);
    font-size: 0.82rem;
    color: #92400e;
    display: flex;
    gap: 8px;
    align-items: flex-start;
}

.info-box .info-icon {
    flex-shrink: 0;
    margin-top: 1px;
}

/* ─── Toast ──────────────────────────────────────────── */
.toast {
    position: fixed;
    bottom: 28px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background: #1e293b;
    color: #fff;
    padding: 10px 22px;
    border-radius: 20px;
    font-size: 0.875rem;
    opacity: 0;
    transition: all 0.3s ease;
    pointer-events: none;
    z-index: 9999;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* ─── Responsive ─────────────────────────────────────── */
@media (max-width: 640px) {
    .header-inner {
        gap: 12px;
    }

    .logo span {
        display: none;
    }

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

    .cat-tab {
        padding: 6px 12px;
        font-size: 0.8rem;
    }

    .main-wrap {
        padding: 20px 14px 50px;
    }
}

@media (max-width: 400px) {
    .unit-grid {
        grid-template-columns: 1fr;
    }
}