:root {
    --primary-color: #6366f1;
    --secondary-color: #ec4899;
    --accent-color: #8b5cf6;
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --text-color: #ffffff;
    --text-muted: #94a3b8;
    --card-bg: rgba(15, 23, 42, 0.6);
}

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

body {
    background-color: #0f172a;
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow-x: hidden;
    position: relative;
}

/* Dynamic Background Blobs */
.background-blobs {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.blob {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.6;
    animation: float 10s infinite alternate ease-in-out;
}

.blob-1 {
    width: 500px;
    height: 500px;
    background: var(--primary-color);
    top: -100px;
    left: -100px;
}

.blob-2 {
    width: 400px;
    height: 400px;
    background: var(--secondary-color);
    bottom: -50px;
    right: -50px;
    animation-delay: -5s;
}

.blob-3 {
    width: 300px;
    height: 300px;
    background: var(--accent-color);
    top: 40%;
    left: 40%;
    animation-duration: 15s;
}

@keyframes float {
    0% { transform: translate(0, 0) rotate(0deg); }
    100% { transform: translate(50px, 50px) rotate(10deg); }
}

/* Container */
.container {
    width: 100%;
    max-width: 900px;
    padding: 20px;
    z-index: 1;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 10px;
    letter-spacing: -1px;
}

header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Converter Card */
.converter-card {
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

/* Navigation */
.category-nav {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--glass-border);
}

.nav-btn {
    background: transparent;
    border: 1px solid var(--glass-border);
    color: var(--text-muted);
    padding: 10px 20px;
    border-radius: 12px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-btn i {
    font-size: 1.1em;
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.05);
    color: #fff;
    transform: translateY(-2px);
}

.nav-btn.active {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
    border-color: rgba(255, 255, 255, 0.3);
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.2);
}

/* Converter Body */
.converter-body {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    margin-bottom: 30px;
}

.input-group {
    flex: 1;
}

.input-group label {
    display: block;
    margin-bottom: 10px;
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 500;
}

.input-wrapper {
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 15px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    transition: border-color 0.3s ease;
}

.input-wrapper:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.input-wrapper input {
    width: 100%;
    background: transparent;
    border: none;
    color: #fff;
    font-size: 2rem;
    font-weight: 700;
    outline: none;
    padding: 0;
}

.input-wrapper input::placeholder {
    color: rgba(255, 255, 255, 0.2);
}

.input-wrapper select {
    width: 100%;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1rem;
    outline: none;
    cursor: pointer;
    appearance: none; /* Remove default arrow */
    -webkit-appearance: none;
    padding-right: 20px;
    font-weight: 500;
}

/* Custom select arrow logic fits better with a wrapper, 
   but for simplicity, we keep standard select for now or add a pseudo element if needed.
   Let's just style the options black to be readable */
.input-wrapper select option {
    background-color: #1e293b;
    color: #fff;
}

.swap-icon {
    display: flex;
    align-items: center;
    padding-top: 30px; /* Align with input box roughly */
}

#swap-btn {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    color: #fff;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2rem;
}

#swap-btn:hover {
    background: var(--primary-color);
    transform: rotate(180deg);
    border-color: var(--primary-color);
}

.formula-display {
    text-align: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--glass-border);
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Responsive */
@media (max-width: 768px) {
    .converter-body {
        flex-direction: column;
    }

    .swap-icon {
        padding-top: 0;
        transform: rotate(90deg);
    }
    
    #swap-btn:hover {
        transform: rotate(270deg); /* 90 + 180 */
    }

    header h1 {
        font-size: 2.2rem;
    }
    
    .converter-card, .constants-card {
        padding: 20px;
    }

    .constants-list {
        grid-template-columns: 1fr;
    }
}

/* Constants Page Styles */
.constants-card {
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.constants-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.constant-item {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 20px;
    display: flex;
    align-items: flex-start;
    gap: 15px;
    transition: all 0.3s ease;
}

.constant-item:hover {
    background: rgba(255, 255, 255, 0.08);
    transform: translateY(-5px);
    border-color: rgba(255, 255, 255, 0.2);
}

.constant-icon {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
    width: 40px;
    height: 40px;
    border-radius: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.1rem;
}

.constant-info h3 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 5px;
    color: var(--text-color);
}

.constant-info .value {
    font-size: 1.1rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 2px;
}

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

.nav-actions {
    display: flex;
    justify-content: center;
    margin-top: 30px;
    border-top: 1px solid var(--glass-border);
    padding-top: 20px;
}

.back-btn, .constants-link-btn {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    transition: color 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.back-btn:hover, .constants-link-btn:hover {
    color: #fff;
}

/* Footer Styles */
footer {
    text-align: center;
    margin-top: 40px;
    color: var(--text-muted);
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Link to constants on index page */
.constants-link-container {
    text-align: center;
    margin-top: 20px;
}