/* ===================================================
   ConvertHub — Premium Design System
   =================================================== */

:root {
    /*
     * Color system: one neutral ramp (blue-slate) + two semantic accents.
     * — Currency / brand: cool sky–cyan (trust, finance).
     * — Temperature: warm amber (heat metaphor), hue-separated from brand.
     * — Success / danger: fixed semantics for toasts and errors (WCAG on dark).
     * RGB tuples pair with rgba(var(--rgb-*), α) for consistent transparency.
     */
    --bg-primary: #090b10;
    --bg-secondary: #121620;
    --bg-card: rgba(18, 22, 32, 0.78);
    --bg-card-hover: rgba(28, 33, 46, 0.92);
    --bg-input: rgba(255, 255, 255, 0.045);
    --bg-input-focus: rgba(255, 255, 255, 0.08);

    --text-primary: #eef1f6;
    --text-secondary: #97a3b8;
    --text-muted: #5c6b82;

    --rgb-surface: 9, 11, 16;
    --rgb-brand: 56, 189, 248;
    --rgb-brand-deep: 14, 165, 233;
    --rgb-warm: 251, 146, 60;
    --rgb-warm-deep: 234, 88, 12;
    --rgb-success: 74, 222, 128;
    --rgb-danger: 248, 113, 113;

    --accent-brand: #38bdf8;
    --accent-brand-deep: #0ea5e9;
    /* Names kept for existing selectors / inline script styles */
    --accent-indigo: #38bdf8;
    --accent-rose: #fb923c;
    --accent-success: #4ade80;
    --accent-danger: #f87171;
    --accent-teal: var(--accent-success);

    --gradient-primary: linear-gradient(128deg, #0284c7 0%, #22d3ee 48%, #7dd3fc 100%);
    --gradient-currency: linear-gradient(135deg, #0ea5e9, #38bdf8);
    --gradient-temp: linear-gradient(135deg, #ea580c, #fdba74);
    --gradient-bg: linear-gradient(165deg, rgba(var(--rgb-brand-deep), 0.12), rgba(var(--rgb-brand), 0.05));

    --border-subtle: rgba(255, 255, 255, 0.065);
    --border-active: rgba(var(--rgb-brand), 0.42);

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.38);
    --shadow-md: 0 10px 36px rgba(0, 0, 0, 0.48);
    --shadow-lg: 0 24px 80px rgba(0, 0, 0, 0.55);
    --shadow-glow: 0 0 56px rgba(var(--rgb-brand), 0.2);
    --shadow-glow-temp: 0 0 48px rgba(var(--rgb-warm), 0.18);

    --radius-sm: 10px;
    --radius-md: 14px;
    --radius-lg: 18px;
    --radius-xl: 26px;

    --font: 'Outfit', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'IBM Plex Mono', ui-monospace, monospace;
    --transition: 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
}

.skip-link {
    position: absolute;
    left: -9999px;
    top: 12px;
    z-index: 200;
    padding: 10px 18px;
    background: var(--gradient-primary);
    color: #fff;
    font-weight: 600;
    font-size: 0.85rem;
    border-radius: var(--radius-sm);
    text-decoration: none;
}

.skip-link:focus {
    left: 12px;
}

/* ===== Mesh + noise overlay ===== */
.bg-mesh {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    background:
        radial-gradient(ellipse 80% 50% at 18% -8%, rgba(var(--rgb-brand-deep), 0.22), transparent 56%),
        radial-gradient(ellipse 55% 42% at 100% 10%, rgba(var(--rgb-brand), 0.1), transparent 52%),
        radial-gradient(ellipse 48% 38% at 52% 100%, rgba(var(--rgb-warm), 0.08), transparent 58%);
}

.bg-mesh::after {
    content: '';
    position: absolute;
    inset: 0;
    opacity: 0.035;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ===== Animated Background Orbs ===== */
.bg-orbs {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
    overflow: hidden;
}

.orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.4;
    animation: float 20s ease-in-out infinite;
}

.orb-1 {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(var(--rgb-brand), 0.26), transparent 70%);
    top: -100px;
    right: -100px;
    animation-delay: 0s;
}

.orb-2 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(var(--rgb-brand-deep), 0.2), transparent 70%);
    bottom: -50px;
    left: -50px;
    animation-delay: -7s;
}

.orb-3 {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(var(--rgb-warm), 0.16), transparent 70%);
    top: 50%;
    left: 50%;
    animation-delay: -14s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(50px, -30px) scale(1.05); }
    50% { transform: translate(-20px, 40px) scale(0.95); }
    75% { transform: translate(30px, 20px) scale(1.02); }
}

/* ===== Navbar ===== */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    flex-wrap: wrap;
    padding: 14px clamp(16px, 4vw, 40px);
    margin: 12px clamp(12px, 3vw, 28px) 0;
    max-width: 1120px;
    margin-left: auto;
    margin-right: auto;
    border-radius: var(--radius-xl);
    background: rgba(var(--rgb-surface), 0.72);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border: 1px solid var(--border-subtle);
    box-shadow: var(--shadow-md);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.brand-icon {
    width: 32px;
    height: 32px;
}

.nav-tabs {
    display: flex;
    gap: 4px;
    background: rgba(255, 255, 255, 0.04);
    padding: 4px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
}

.nav-tab {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-sm);
    background: transparent;
    color: var(--text-secondary);
    font-family: var(--font);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.nav-tab:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav-tab.active {
    color: white;
    background: var(--gradient-currency);
    box-shadow: 0 2px 14px rgba(var(--rgb-brand), 0.32);
}

.nav-tab.active.temp-active {
    background: var(--gradient-temp);
    box-shadow: 0 2px 14px rgba(var(--rgb-warm), 0.32);
}

.github-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    border: 1px solid var(--border-subtle);
    background: rgba(255, 255, 255, 0.04);
    transition: var(--transition);
    text-decoration: none;
    flex-shrink: 0;
}

.github-link:hover {
    color: white;
    border-color: var(--accent-brand);
    background: rgba(var(--rgb-brand), 0.1);
    box-shadow: 0 0 20px rgba(var(--rgb-brand), 0.18);
    transform: translateY(-2px);
}

/* ===== Hero ===== */
.hero {
    position: relative;
    z-index: 1;
    text-align: center;
    padding: 40px 40px 20px;
}

.hero-badge {
    display: inline-block;
    padding: 8px 18px;
    border-radius: 100px;
    background: rgba(var(--rgb-brand-deep), 0.14);
    border: 1px solid rgba(var(--rgb-brand), 0.28);
    color: var(--accent-brand);
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    margin-bottom: 22px;
    animation: fadeInUp 0.6s ease-out;
}

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: -0.03em;
    margin-bottom: 16px;
    animation: fadeInUp 0.6s ease-out 0.1s both;
}

.gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-title-accent {
    color: var(--text-secondary);
    font-weight: 600;
}

.hero-subtitle {
    font-size: clamp(1rem, 2.2vw, 1.15rem);
    color: var(--text-secondary);
    max-width: 34rem;
    margin: 0 auto 28px;
    line-height: 1.65;
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

.hero-features {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px 20px;
    font-size: 0.88rem;
    color: var(--text-secondary);
    animation: fadeInUp 0.6s ease-out 0.28s both;
}

.hero-features li {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 14px;
    border-radius: 100px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border-subtle);
}

.feature-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    flex-shrink: 0;
}

.currency-dot { background: var(--gradient-currency); box-shadow: 0 0 12px rgba(var(--rgb-brand), 0.42); }
.temp-dot { background: var(--gradient-temp); box-shadow: 0 0 12px rgba(var(--rgb-warm), 0.4); }
.neutral-dot { background: var(--accent-success); box-shadow: 0 0 10px rgba(var(--rgb-success), 0.35); }

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== Main Content ===== */
.main-content {
    position: relative;
    z-index: 1;
    max-width: 920px;
    margin: 0 auto;
    padding: 28px clamp(16px, 4vw, 32px) 72px;
}

/* ===== Converter Card ===== */
.converter-card {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-xl);
    padding: clamp(22px, 4vw, 36px);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    box-shadow: var(--shadow-md);
    animation: fadeInUp 0.5s ease-out;
    transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.converter-card:hover {
    border-color: var(--border-active);
    box-shadow: var(--shadow-glow);
}

#section-temperature .converter-card:hover {
    border-color: rgba(var(--rgb-warm-deep), 0.35);
    box-shadow: var(--shadow-glow-temp);
}

.card-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 28px;
}

.card-icon {
    width: 52px;
    height: 52px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.currency-icon {
    background: linear-gradient(135deg, rgba(var(--rgb-brand), 0.12), rgba(var(--rgb-brand-deep), 0.07));
    color: var(--accent-indigo);
    border: 1px solid rgba(var(--rgb-brand), 0.22);
}

.temp-icon {
    background: linear-gradient(135deg, rgba(var(--rgb-warm), 0.14), rgba(var(--rgb-warm-deep), 0.08));
    color: var(--accent-rose);
    border: 1px solid rgba(var(--rgb-warm), 0.24);
}

.card-title {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.01em;
}

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

.api-badge {
    margin-left: auto;
    padding: 4px 12px;
    border-radius: 100px;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    background: rgba(var(--rgb-brand), 0.1);
    color: var(--accent-indigo);
    border: 1px solid rgba(var(--rgb-brand), 0.22);
}

.temp-badge {
    background: rgba(var(--rgb-warm), 0.1);
    color: var(--accent-rose);
    border: 1px solid rgba(var(--rgb-warm), 0.22);
}

/* ===== Input Group ===== */
.input-group {
    margin-bottom: 0;
}

.input-label {
    display: block;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.input-wrapper {
    display: flex;
    align-items: center;
    gap: 8px;
    background: var(--bg-input);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 6px 6px 6px 16px;
    transition: var(--transition);
}

.input-wrapper:focus-within {
    background: var(--bg-input-focus);
    border-color: var(--accent-indigo);
    box-shadow: 0 0 0 3px rgba(var(--rgb-brand), 0.12);
}

#section-temperature .input-wrapper:focus-within {
    border-color: var(--accent-rose);
    box-shadow: 0 0 0 3px rgba(var(--rgb-warm), 0.12);
}

.input-prefix {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-muted);
}

.input-field {
    flex: 1;
    border: none;
    background: transparent;
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 1.1rem;
    font-weight: 500;
    padding: 10px 0;
    outline: none;
    min-width: 0;
}

.input-field::placeholder {
    color: var(--text-muted);
}

/* Remove number input spinners */
.input-field::-webkit-outer-spin-button,
.input-field::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
.input-field[type=number] { -moz-appearance: textfield; }

.unit-select {
    padding: 10px 12px;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-primary);
    font-family: var(--font);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    outline: none;
    transition: var(--transition);
}

.unit-select:hover { background: rgba(255, 255, 255, 0.08); }
.unit-select:focus { border-color: var(--accent-rose); }

.unit-select option {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.convert-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-sm);
    background: var(--gradient-primary);
    color: white;
    font-family: var(--font);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.convert-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 22px rgba(var(--rgb-brand), 0.36);
}

.convert-btn:active {
    transform: translateY(0);
}

.convert-btn.loading {
    opacity: 0.7;
    pointer-events: none;
}

.temp-btn {
    background: var(--gradient-temp);
}

.temp-btn:hover {
    box-shadow: 0 4px 22px rgba(var(--rgb-warm), 0.36);
}

/* ===== Result Panel ===== */
.result-panel {
    margin-top: 24px;
    padding: 24px;
    background: var(--gradient-bg);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    animation: slideDown 0.4s ease-out;
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.result-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 24px;
}

.result-item {
    text-align: center;
}

.result-label {
    display: block;
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 4px;
}

.result-value {
    font-family: var(--font-mono);
    font-size: 1.45rem;
    font-weight: 600;
    letter-spacing: -0.02em;
}

.result-value.highlight {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: clamp(1.5rem, 4vw, 1.95rem);
    font-weight: 700;
}

.result-value.highlight-temp {
    background: var(--gradient-temp);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: clamp(1.5rem, 4vw, 1.95rem);
    font-weight: 700;
}

.result-arrow {
    color: var(--accent-indigo);
    animation: pulse 2s ease-in-out infinite;
}

.temp-arrow {
    color: var(--accent-rose);
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}

.result-meta {
    display: flex;
    justify-content: space-between;
    margin-top: 16px;
    padding-top: 12px;
    border-top: 1px solid var(--border-subtle);
    font-size: 0.78rem;
    color: var(--text-muted);
}

/* ===== History Card ===== */
.history-card {
    margin-top: 24px;
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-xl);
    padding: 24px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    animation: fadeInUp 0.5s ease-out 0.1s both;
}

.history-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
}

.history-header h3 {
    font-size: 1rem;
    font-weight: 600;
}

.refresh-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    background: transparent;
    color: var(--text-secondary);
    font-family: var(--font);
    font-size: 0.78rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.refresh-btn:hover {
    color: var(--accent-indigo);
    border-color: var(--accent-indigo);
    background: rgba(var(--rgb-brand), 0.06);
}

.temp-refresh:hover {
    color: var(--accent-rose);
    border-color: var(--accent-rose);
    background: rgba(var(--rgb-warm), 0.07);
}

.history-table-wrapper {
    overflow-x: auto;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
}

.history-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.83rem;
}

.history-table thead {
    background: rgba(255, 255, 255, 0.03);
}

.history-table th {
    padding: 12px 16px;
    text-align: left;
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    border-bottom: 1px solid var(--border-subtle);
}

.history-table td {
    padding: 12px 16px;
    border-bottom: 1px solid var(--border-subtle);
    color: var(--text-primary);
}

.history-table tbody tr {
    transition: var(--transition);
}

.history-table tbody tr:hover {
    background: rgba(255, 255, 255, 0.03);
}

.history-table tbody tr:last-child td {
    border-bottom: none;
}

.history-error {
    color: var(--accent-danger) !important;
    font-style: normal;
    font-weight: 500;
}

/* ===== Utility: Hidden ===== */
.hidden {
    display: none !important;
}

/* ===== Footer ===== */
.footer {
    position: relative;
    z-index: 1;
    text-align: center;
    padding: 28px 24px 40px;
    color: var(--text-muted);
    font-size: 0.84rem;
    border-top: 1px solid var(--border-subtle);
}

.footer a {
    color: var(--accent-brand);
    text-decoration: none;
    font-weight: 500;
}

.footer a:hover {
    text-decoration: underline;
    color: #7dd3fc;
}

.heart {
    color: var(--accent-danger);
    animation: heartbeat 1.5s ease-in-out infinite;
    display: inline-block;
}

@keyframes heartbeat {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.2); }
}

/* ===== Toast Notification ===== */
.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    font-weight: 500;
    z-index: 1000;
    animation: toastIn 0.4s ease-out forwards;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.toast.success {
    background: rgba(var(--rgb-success), 0.12);
    border: 1px solid rgba(var(--rgb-success), 0.34);
    color: var(--accent-success);
}

.toast.error {
    background: rgba(var(--rgb-danger), 0.12);
    border: 1px solid rgba(var(--rgb-danger), 0.3);
    color: var(--accent-danger);
}

@keyframes toastIn {
    from { opacity: 0; transform: translateX(-50%) translateY(20px); }
    to { opacity: 1; transform: translateX(-50%) translateY(0); }
}

@keyframes toastOut {
    from { opacity: 1; transform: translateX(-50%) translateY(0); }
    to { opacity: 0; transform: translateX(-50%) translateY(20px); }
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .navbar {
        flex-direction: column;
        align-items: stretch;
        gap: 14px;
        padding: 14px 16px;
        margin: 8px 12px 0;
    }

    .nav-tabs {
        width: 100%;
        justify-content: stretch;
    }

    .nav-tab {
        flex: 1;
        justify-content: center;
    }

    .github-link {
        align-self: center;
    }

    .hero {
        padding: 32px 20px 16px;
    }

    .hero-title {
        font-size: 2rem;
    }

    .main-content {
        padding: 16px;
    }

    .converter-card {
        padding: 20px;
    }

    .card-header {
        flex-wrap: wrap;
    }

    .api-badge {
        margin-left: 0;
    }

    .input-wrapper {
        flex-wrap: wrap;
        gap: 8px;
        padding: 8px;
    }

    .input-prefix {
        padding-left: 8px;
    }

    .input-field {
        padding-left: 8px;
    }

    .convert-btn {
        width: 100%;
        justify-content: center;
    }

    .unit-select {
        flex: 1;
    }

    .result-row {
        flex-direction: column;
        gap: 12px;
    }

    .result-arrow {
        transform: rotate(90deg);
    }
}

@media (prefers-reduced-motion: reduce) {
    .orb {
        animation: none;
    }

    .result-arrow {
        animation: none;
    }

    .heart {
        animation: none;
    }
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.2);
}