:root {
    --primary: #4361ee;
    --primary-dark: #3a56d4;
    --secondary: #7209b7;
    --accent: #f72585;
    --dark: #212529;
    --light: #f8f9fa;
    --gray: #6c757d;
    --success: #4cc9f0;
    --card-bg: rgba(255, 255, 255, 0.95);
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', system-ui, sans-serif;
}

body {
    background: linear-gradient(135deg, #4361ee, #3a0ca3);
    color: var(--dark);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 5px;
}

/* Header */
.site-header {
    background-color: transparent;
    /* background: linear-gradient(135deg, #1a252f, #2c3e50); */
    color: #ffffff;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 5px 20px;
    border-bottom: 2px solid rgba(0, 0, 0, 0.1);
    width: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-family: 'Orbitron', sans-serif;
    font-size: 1.8rem;
    font-weight: 700;
}

.logo img {
    height: 40px;
    margin-right: 10px;
    object-fit: cover;
    position: relative;
    top: 2px;
    filter: drop-shadow(0 0 3px rgb(255, 255, 255));
}

.logo a span {
    font-family: 'Poppins', sans-serif;
    font-size: 1.5rem;
    font-weight: bolder;
    background: linear-gradient(to right, #aa00ff, #0015ff, #1b9400, #ffae00, #ff0000, #ffae00, #1b9400, #0015ff, #aa00ff);
    background-size: 200%;
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: animate-gradient 2.5s linear infinite;
    position: relative;
    top: -3px;
}

@keyframes animate-gradient {
    to {
        background-position: 200%;
    }
}

.logo a {
    text-decoration: none;
    color: white;
}

.nav-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    margin-left: 20px;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.nav-links a:hover {
    color: #ffffff;
}

nav a::after {
    content: "";
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: #ffffff;
    transition: width 0.3s ease;
}

nav a:hover::after {
    width: 100%;
}

@media (min-width: 350px) and (max-width:390px) {
    .nav-links a {
        margin: 0 0 0 10px;
    }

    .site-header {
        padding: 5px 10px;
    }
}

@media (min-width: 300px) and (max-width:350px) {
    .nav-links a {
        font-size: small;
        margin: 0 0 0 10px;
    }

    .logo {
        gap: 0;
    }

    .logo a span {
        font-size: 1.2rem;
        position: relative;
        top: -5px;
    }

    .site-header {
        padding: 5px 10px;
    }
}



.container {
    max-width: 900px;
    width: 100%;
    margin: 0 auto;
}

header {
    text-align: center;
    padding: 40px 20px;
    color: white;
    max-width: 800px;
    margin: 0 auto;
}

header h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 10px;
    letter-spacing: -0.5px;
}

header p {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

.converter-card {
    background: var(--card-bg);
    border-radius: 20px;
    box-shadow: var(--shadow);
    overflow: auto;
    margin-bottom: 40px;
    transition: var(--transition);
}

.card-header {
    background: linear-gradient(to right, var(--primary), var(--secondary));
    padding: 20px;
    color: white;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.category-selector {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    justify-content: center;
}

.category-btn {
    background: rgba(255, 255, 255, 0.15);
    border: none;
    color: white;
    padding: 10px 20px;
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 8px;
    white-space: nowrap;
}

.category-btn:hover {
    background: rgba(255, 255, 255, 0.25);
}

.category-btn.active {
    background: white;
    color: var(--primary);
}

.converter-body {
    padding: 30px;
}

.conversion-area {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 20px;
    align-items: center;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.input-group label {
    font-weight: 600;
    color: var(--gray);
    font-size: 0.9rem;
}

.input-container {
    display: flex;
    border: 2px solid #e9ecef;
    border-radius: 12px;
    overflow: hidden;
    transition: var(--transition);
    height: 60px;
}

.input-container:focus-within {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
}

.input-container input {
    flex: 1;
    padding: 10px 15px;
    border: none;
    font-size: 1.1rem;
    font-weight: 500;
    outline: none;
    background: #f8f9fa;
    min-width: 0;
    height: 100%;
}

.unit-selector {
    background: white;
    border: none;
    padding: 0 15px;
    font-size: 1rem;
    font-weight: 600;
    border-left: 2px solid #e9ecef;
    cursor: pointer;
    min-width: 80px;
    max-width: 120px;
    appearance: none;
    background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='currentColor' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
    background-repeat: no-repeat;
    background-position: right 10px center;
    background-size: 1em;
    height: 100%;
}

.swap-btn {
    background: var(--light);
    border: 2px solid #e9ecef;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    align-self: center;
}

.swap-btn:hover {
    background: var(--primary);
    color: white;
    transform: rotate(90deg);
}

.conversion-results {
    background: var(--light);
    border-radius: 15px;
    padding: 25px;
    margin-top: 25px;
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 15px;
}

.result-card {
    background: white;
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.result-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.1);
}

.result-unit {
    font-size: 0.9rem;
    color: var(--gray);
    margin-bottom: 8px;
}

.result-value {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--primary);
}

footer {
    color: white;
    text-align: center;
    padding: 30px;
    font-size: 0.9rem;
    opacity: 0.8;
    margin-top: auto;
}

.history-section {
    background: var(--card-bg);
    border-radius: 20px;
    box-shadow: var(--shadow);
    padding: 30px;
    width: 100%;
    margin-top: 20px;
}

.history-section h3 {
    margin-bottom: 20px;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.history-items {
    display: flex;
    flex-direction: column;
    gap: 12px;
    max-height: 300px;
    overflow-y: auto;
}

.history-item {
    display: flex;
    justify-content: space-between;
    padding: 15px;
    background: #f8f9fa;
    border-radius: 10px;
    font-size: 0.95rem;
}

.history-item .value {
    font-weight: 600;
}

@media (max-width: 768px) {
    .conversion-area {
        grid-template-columns: 1fr;
    }

    .swap-btn {
        margin: 15px 0;
        transform: rotate(90deg);
    }

    .swap-btn:hover {
        transform: rotate(180deg);
    }

    header h1 {
        font-size: 2.2rem;
    }

    header p {
        font-size: 1rem;
    }

    .category-selector {
        gap: 8px;
    }

    .category-btn {
        padding: 8px 12px;
        font-size: 0.9rem;
    }

    .converter-body {
        padding: 20px;
    }

    .input-container {
        height: 50px;
    }

    .input-container input {
        padding: 8px 12px;
        font-size: 1rem;
    }

    .unit-selector {
        padding: 0 10px;
        min-width: 70px;
        max-width: 90px;
        font-size: 0.9rem;
        background-position: right 5px center;
    }
}

@media (max-width: 480px) {
    header {
        padding: 30px 15px;
    }

    header h1 {
        font-size: 1.8rem;
    }

    .card-header {
        padding: 15px 10px;
    }

    .category-btn {
        padding: 6px 10px;
        font-size: 0.8rem;
    }

    .input-group label {
        font-size: 0.8rem;
    }

    .input-container {
        height: 45px;
    }

    .input-container input {
        padding: 6px 10px;
        font-size: 0.9rem;
    }

    .unit-selector {
        min-width: 60px;
        max-width: 80px;
        font-size: 0.8rem;
        padding: 0 8px;
    }

    .swap-btn {
        width: 45px;
        height: 45px;
    }

    .conversion-results {
        padding: 15px;
    }

    .results-grid {
        grid-template-columns: 1fr 1fr;
        gap: 10px;
    }

    .result-card {
        padding: 15px;
    }

    .result-value {
        font-size: 1.2rem;
    }
}

.seo-section {
    max-width: 900px;
    margin: 40px auto;
    padding: 30px 20px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    line-height: 1.8;
    font-size: 1rem;
    color: #212529;
    margin-bottom: 0;
}

.seo-section h2 {
    font-size: 1.8rem;
    color: #4361ee;
    margin-bottom: 20px;
    border-bottom: 2px solid #4361ee;
    padding-bottom: 10px;
}

.seo-section h3 {
    font-size: 1.4rem;
    margin-top: 30px;
    margin-bottom: 15px;
    color: #3f37c9;
}

.seo-section p {
    margin-bottom: 15px;
}

.seo-section ul {
    list-style: disc;
    padding-left: 20px;
    margin-bottom: 20px;
}

.seo-section ul li {
    margin-bottom: 10px;
}

.seo-section ol {
    list-style: decimal;
    padding-left: 20px;
    margin-bottom: 20px;
}

.seo-section ol li {
    margin-bottom: 10px;
}

.seo-section strong {
    color: #4361ee;
}

.seo-section a {
    color: #3f37c9;
    text-decoration: underline;
}

.seo-section a:hover {
    text-decoration: none;
}

footer {
    margin: 20px;
    text-align: center;
}

footer p a {
    text-decoration: none;
    font-weight: bold;
    color: #ffd500;
}