/* Base Variables - restoring Premium Dark Theme */
:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #ec4899;
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-color: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: #334155;
    --input-bg: #334155;
    --success: #10b981;
    --font-family: 'Inter', system-ui, -apple-system, sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.2s;
}

/* Navbar - Restored */
.navbar {
    background-color: rgba(30, 41, 59, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 9999;
    padding: 1rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--text-muted);
    font-weight: 500;
}

.nav-links a:hover {
    color: var(--primary-color);
}

.hamburger {
    display: none;
    cursor: pointer;
    font-size: 1.5rem;
}

/* Main Section */
main {
    flex: 1;
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-align: center;
    color: var(--text-color);
}

.hero-text {
    max-width: 600px;
    margin: 0 auto 2rem;
    color: var(--text-muted);
    text-align: center;
}

.hero-section {
    text-align: center;
    margin-bottom: 2rem;
}

/* Calculator Card */
.calculator-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 2rem;
    max-width: 600px;
    margin: 0 auto;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

/* Form Styles */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-color);
    font-weight: 500;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    color: var(--text-color);
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

/* Buttons */
.btn-primary {
    width: 100%;
    padding: 0.875rem 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(79, 70, 229, 0.4);
}

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

/* Result Box */
.result-box {
    margin-top: 2rem;
    padding: 1.5rem;
    background: rgba(79, 70, 229, 0.1);
    border: 1px solid var(--primary-color);
    border-radius: 0.75rem;
    text-align: center;
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 0.3s, transform 0.3s;
}

.result-box.active {
    opacity: 1;
    transform: translateY(0);
}

.result-box p {
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.result-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--success);
    margin: 0.5rem 0;
}

/* Toggle Container */
.toggle-container {
    display: none;
}

/* Display */
.display-container {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    margin-bottom: 1rem;
    padding: 1rem;
    text-align: right;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 80px;
}

.display-sub {
    font-size: 0.9rem;
    color: var(--text-muted);
    min-height: 1.2rem;
}

.display-main {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-color);
}

/* Calculator Grid */
.adv-calc-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 4px;
}

.sci-key {
    display: block;
}

.adv-calc-grid button {
    padding: 1rem 0;
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
    background: var(--input-bg);
    color: white;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
    user-select: none;
    font-weight: 500;
}

.adv-calc-grid button:hover {
    background: var(--border-color);
    transform: translateY(-2px);
}

.adv-calc-grid button:active {
    transform: scale(0.98);
}

/* Button Colors */
.btn-func {
    color: var(--secondary-color) !important;
    background: rgba(236, 72, 153, 0.1) !important;
}

.btn-op {
    background: var(--border-color) !important;
    color: white !important;
}

.btn-action {
    background: var(--primary-color) !important;
    font-weight: bold;
}

.btn-danger {
    color: #ef4444 !important;
    background: rgba(239, 68, 68, 0.1) !important;
}

.btn-num {
    background: var(--card-bg) !important;
}

/* Categories */
#categories h2 {
    text-align: center;
    margin-bottom: 2rem;
    margin-top: 3rem;
}

.calc-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 1.5rem;
}

.calc-link-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    padding: 1.5rem;
    transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
    display: flex;
    flex-direction: column;
}

.calc-link-card:hover {
    transform: translateY(-4px);
    border-color: var(--primary-color);
    box-shadow: 0 8px 20px rgba(79, 70, 229, 0.3);
}

.calc-link-card h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.calc-link-card p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* Footer */
footer {
    background-color: var(--card-bg);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    margin-top: auto;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    justify-content: center;
}

.footer-content a {
    color: var(--text-muted);
    transition: color 0.2s;
}

.footer-content a:hover {
    color: var(--primary-color);
}

/* Media Queries */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        flex-direction: column;
        background: var(--card-bg);
        padding: 1rem;
        border-bottom: 1px solid var(--border-color);
    }

    .nav-links.active {
        display: flex;
    }

    .nav-links.active .mobile-search {
        display: flex !important;
    }

    .hamburger {
        display: block;
    }

    h1 {
        font-size: 2rem;
    }

    .calculator-card {
        padding: 1.5rem;
    }

    .sci-key {
        display: none !important;
    }

    .toggle-container {
        display: flex;
        justify-content: center;
        margin-bottom: 1rem;
    }

    .mode-toggle {
        padding: 0.5rem 1rem;
        background: var(--primary-color);
        color: white;
        border: none;
        border-radius: 0.5rem;
        cursor: pointer;
        font-weight: 500;
    }

    .calculator-card.scientific .sci-key {
        display: block !important;
    }

    .calculator-card.scientific .adv-calc-grid {
        grid-template-columns: repeat(5, 1fr) !important;
    }

    .adv-calc-grid {
        grid-template-columns: repeat(4, 1fr) !important;
    }
}

@media (min-width: 720px) {
    .adv-calc-grid {
        grid-template-columns: repeat(5, 1fr) !important;
    }
}

/* Global Search Bar Styles for All Pages */
.header-search {
    display: flex;
    gap: 0.5rem;
    margin-left: auto;
}

.header-search input {
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    background: var(--input-bg);
    border: 1px solid var(--border-color);
    color: white;
    font-family: inherit;
    font-size: 0.9rem;
    width: 200px;
}

.header-search button {
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: all 0.2s;
}

.header-search button:hover {
    background: var(--primary-hover);
}

.mobile-search {
    display: none;
}

/* Mobile Search in Hamburger Menu */
@media (max-width: 768px) {
    .header-search {
        display: none !important;
    }

    .nav-links.active .mobile-search {
        display: flex !important;
        padding: 1rem 0;
        gap: 0.5rem;
    }

    .mobile-search input {
        flex: 1;
        padding: 0.75rem 1rem;
        border-radius: 0.5rem;
        background: var(--input-bg);
        border: 1px solid var(--border-color);
        color: white;
        font-family: inherit;
        font-size: 0.9rem;
    }

    .mobile-search button {
        padding: 0.75rem 1rem;
        background: var(--primary-color);
        color: white;
        border: none;
        border-radius: 0.5rem;
        cursor: pointer;
        font-size: 1rem;
        font-weight: 600;
    }
}