/* =============================================
   PROFESSIONAL TVM WEBSITE - CUSTOM STYLES
   ============================================= */

/* Color Variables */
:root {
    --primary-navy: #1e3a5f;
    --secondary-navy: #2c5282;
    --accent-gold: #d4af37;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --text-dark: #2d3748;
    --text-muted: #718096;
    --border-color: #e2e8f0;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-dark);
    background: linear-gradient(to bottom, #f8f9fa 0%, #e9ecef 50%, #f8f9fa 100%);
    background-attachment: fixed;
}

/* =============================================
   NAVIGATION BAR
   ============================================= */
.navbar {
    background: linear-gradient(135deg, var(--primary-navy), var(--secondary-navy)) !important;
    padding: 0.75rem 0;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.navbar-brand {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    color: white !important;
}

.navbar-toggler {
    border: 2px solid rgba(255, 255, 255, 0.5);
    padding: 0.4rem 0.6rem;
}

.navbar-toggler:focus {
    box-shadow: 0 0 0 0.2rem rgba(255, 255, 255, 0.3);
    outline: none;
}

.navbar-toggler-icon {
    width: 1.5em;
    height: 1.5em;
}

.navbar-nav {
    gap: 0.5rem;
}

.nav-link {
    color: rgba(255, 255, 255, 0.9) !important;
    font-size: 0.95rem;
    font-weight: 500;
    padding: 0.5rem 1rem !important;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--accent-gold) !important;
    background: rgba(255, 255, 255, 0.1);
}

/* =============================================
   HERO SECTION
   ============================================= */
.hero-section {
    background: 
        linear-gradient(135deg, rgba(30, 58, 95, 0.85) 0%, rgba(44, 82, 130, 0.85) 50%, rgba(59, 107, 168, 0.85) 100%),
        url('../poze/hero.png?v=2.0');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    min-height: 75vh;
    display: flex;
    align-items: center;
    padding: 100px 0 60px;
    position: relative;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        repeating-linear-gradient(90deg, transparent 0px, rgba(255, 255, 255, 0.03) 1px, transparent 2px, transparent 100px),
        repeating-linear-gradient(0deg, transparent 0px, rgba(255, 255, 255, 0.03) 1px, transparent 2px, transparent 100px);
    pointer-events: none;
}

.hero-section::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, transparent, var(--accent-gold), transparent);
    z-index: 1;
}

.hero-title {
    font-size: 2.75rem;
    font-weight: 800;
    color: white;
    margin-bottom: 1rem;
    letter-spacing: -0.5px;
    position: relative;
    z-index: 2;
}

.hero-subtitle {
    font-size: 1.35rem;
    color: var(--accent-gold);
    font-weight: 600;
    margin-bottom: 1rem;
}

.hero-description {
    font-size: 1rem;
    color: rgba(255, 255, 255, 0.85);
    line-height: 1.7;
    max-width: 700px;
    margin: 0 auto 2rem;
}

/* Feature Cards in Hero */
.feature-card {
    background: white;
    border-radius: 8px;
    transition: all 0.3s ease;
    height: 100%;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
}

.feature-card .card-body {
    padding: 1.5rem;
}

.feature-card i {
    font-size: 2.5rem;
    color: var(--primary-navy);
    margin-bottom: 1rem;
}

.feature-card h6 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.feature-card p {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 0;
}

/* =============================================
   SECTION STYLES
   ============================================= */
section#learn {
    background: linear-gradient(135deg, #f0f4f8 0%, #e3edf7 50%, #f0f4f8 100%) !important;
    position: relative;
}

section#learn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 50%, rgba(212, 175, 55, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(30, 58, 95, 0.05) 0%, transparent 50%),
        repeating-linear-gradient(45deg, transparent, transparent 100px, rgba(212, 175, 55, 0.02) 100px, rgba(212, 175, 55, 0.02) 200px);
    pointer-events: none;
}

section#learn::after {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    width: 2px;
    height: 100%;
    background: linear-gradient(to bottom, transparent 0%, rgba(212, 175, 55, 0.2) 50%, transparent 100%);
    pointer-events: none;
}

section#calculators {
    background: linear-gradient(to bottom, #ffffff 0%, #f8f9fa 50%, #ffffff 100%);
    position: relative;
}

section#calculators::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        linear-gradient(90deg, rgba(30, 58, 95, 0.03) 1px, transparent 1px),
        linear-gradient(rgba(30, 58, 95, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    pointer-events: none;
    opacity: 0.5;
}

section#authors {
    background: linear-gradient(135deg, #e8f4f8 0%, #d6eaf8 50%, #e8f4f8 100%) !important;
    position: relative;
    overflow: hidden;
}

section#authors::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: 
        repeating-linear-gradient(0deg, transparent, transparent 2px, rgba(212, 175, 55, 0.03) 2px, rgba(212, 175, 55, 0.03) 4px),
        repeating-linear-gradient(90deg, transparent, transparent 2px, rgba(30, 58, 95, 0.03) 2px, rgba(30, 58, 95, 0.03) 4px);
    background-size: 60px 60px;
    transform: rotate(15deg);
    pointer-events: none;
}

section#authors::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, transparent, var(--accent-gold), transparent);
}

section#contact {
    background: linear-gradient(to bottom, #ffffff 0%, #f0f9ff 100%);
    position: relative;
}

section#contact::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(212, 175, 55, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 90% 80%, rgba(30, 58, 95, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(212, 175, 55, 0.03) 0%, transparent 70%);
    pointer-events: none;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
    z-index: 1;
}

.section-header::after {
    content: '';
    position: absolute;
    bottom: -1.5rem;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, transparent, var(--accent-gold), transparent);
    border-radius: 2px;
}

.section-title {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--primary-navy);
    margin-bottom: 0.75rem;
}

.section-description {
    font-size: 1.05rem;
    color: var(--text-muted);
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.7;
}

/* =============================================
   THEORY CARDS (Learn Section)
   ============================================= */
.theory-card {
    background: white;
    border-radius: 8px;
    border-left: 4px solid var(--accent-gold);
    padding: 1.75rem;
    height: 100%;
    transition: all 0.3s ease;
}

.theory-card:hover {
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
    transform: translateY(-3px);
}

.theory-card h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-navy);
    margin-bottom: 1rem;
}

.theory-card p {
    font-size: 0.95rem;
    color: var(--text-muted);
    line-height: 1.7;
    margin-bottom: 1.25rem;
}

/* Formula Box */
.formula-box {
    background: var(--light-bg);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 1.25rem;
    margin: 1.25rem 0;
}

.formula-box h6 {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--primary-navy);
    margin-bottom: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.formula-display {
    background: white;
    padding: 1rem;
    border-radius: 4px;
    text-align: center;
    margin: 0.75rem 0;
}

.formula-display code {
    font-family: 'Courier New', Courier, monospace;
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--primary-navy);
}

.formula-legend {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 0.75rem;
    margin-bottom: 0;
}

/* Example Alert */
.alert-info {
    background: #e8f4f8;
    border: 1px solid #b8daed;
    border-radius: 6px;
    padding: 1rem;
    margin-top: 1.25rem;
}

.alert-info h6 {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--primary-navy);
    margin-bottom: 0.5rem;
}

.alert-info p {
    font-size: 0.9rem;
    margin-bottom: 0;
}

/* Applications Section */
.applications-section {
    background: linear-gradient(135deg, var(--primary-navy), var(--secondary-navy));
    border-radius: 10px;
    padding: 3rem 2rem;
    margin-top: 3rem;
}

.applications-section h3 {
    color: white;
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2.5rem;
}

.application-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 8px;
    padding: 1.5rem;
    transition: all 0.3s ease;
}

.application-card:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-3px);
}

.application-card h5 {
    color: var(--accent-gold);
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.application-card i {
    font-size: 1.5rem;
}

.application-card p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 0.95rem;
    line-height: 1.7;
    margin-bottom: 0;
}

/* =============================================
   CALCULATOR CARDS
   ============================================= */
.calculator-card {
    background: white;
    border-radius: 8px;
    border-top: 3px solid var(--accent-gold);
    padding: 1.75rem;
    height: 100%;
    transition: all 0.3s ease;
}

.calculator-card:hover {
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
    transform: translateY(-3px);
}

.calculator-card h4 {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--primary-navy);
    margin-bottom: 0.5rem;
}

.calc-description {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 1.25rem;
}

/* Calculator Formula Display */
.calculator-card .formula-box {
    background: var(--light-bg);
    padding: 1rem;
    margin-bottom: 1.5rem;
}

.calculator-card .formula-display code {
    font-size: 1.05rem;
}

/* Form Inputs */
.form-label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.form-control {
    border: 2px solid var(--border-color);
    border-radius: 6px;
    padding: 0.65rem 0.9rem;
    font-size: 0.95rem;
    transition: all 0.3s ease;
}

.form-control:focus {
    border-color: var(--primary-navy);
    box-shadow: 0 0 0 3px rgba(30, 58, 95, 0.1);
    outline: none;
}

/* Calculate Button */
.btn-calculate {
    background: var(--accent-gold);
    color: var(--primary-navy);
    border: none;
    font-weight: 600;
    padding: 0.75rem;
    font-size: 1rem;
    border-radius: 6px;
    width: 100%;
    margin-top: 1rem;
    transition: all 0.3s ease;
}

.btn-calculate:hover {
    background: #c49f2f;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(212, 175, 55, 0.3);
}

/* Result Box */
.result-box {
    background: linear-gradient(135deg, #e8f4f8, #d6eaf8);
    border-left: 5px solid var(--accent-gold);
    border-radius: 8px;
    padding: 1.5rem;
    margin-top: 1.5rem;
    animation: slideIn 0.4s ease;
}

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

.result-box h5 {
    color: var(--primary-navy);
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.result-value {
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary-navy);
    margin-bottom: 1rem;
}

.result-explanation {
    font-size: 0.9rem;
    color: var(--text-dark);
    line-height: 1.7;
}

.result-explanation p {
    margin-bottom: 0.5rem;
}

.result-explanation .small {
    font-size: 0.85rem;
}

/* =============================================
   AUTHORS SECTION
   ============================================= */
.author-card {
    background: white;
    border-radius: 8px;
    border-top: 3px solid var(--accent-gold);
    padding: 2rem;
    text-align: center;
    transition: all 0.3s ease;
    height: 100%;
}

.author-card:hover {
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
    transform: translateY(-5px);
}

.author-avatar {
    width: 150px;
    height: 150px;
    background: linear-gradient(135deg, var(--primary-navy), var(--secondary-navy));
    color: white;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    border: 5px solid var(--accent-gold);
    overflow: hidden;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.author-avatar:hover {
    transform: scale(1.08);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.35);
}

.author-card h4 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-navy);
    margin-bottom: 0.5rem;
}

.author-role {
    color: var(--accent-gold);
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.author-bio {
    font-size: 0.9rem;
    color: var(--text-muted);
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.signature-line {
    padding-top: 1rem;
    border-top: 2px solid var(--border-color);
    margin-top: 1rem;
}

.signature-line em {
    font-family: 'Brush Script MT', 'Comic Sans MS', cursive;
    font-size: 1.4rem;
    color: var(--primary-navy);
    font-style: italic;
}

/* =============================================
   CONTACT SECTION
   ============================================= */
.contact-card {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.contact-card h4,
.contact-card h5 {
    color: var(--primary-navy);
    font-weight: 700;
    margin-bottom: 1.25rem;
}

.contact-form .btn-primary {
    width: 100%;
    padding: 0.75rem;
    font-weight: 600;
}

.contact-info-card {
    background: var(--light-bg);
    border-left: 4px solid var(--accent-gold);
    border-radius: 6px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.contact-info-card h5 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
}

.contact-info-card p,
.contact-info-card li {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.team-list {
    list-style: none;
    padding-left: 0;
}

.team-list li {
    padding-left: 1.5rem;
    position: relative;
}

.team-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--accent-gold);
    font-weight: bold;
}

/* Success Message */
.alert-success {
    background: #d4edda;
    border: 1px solid #c3e6cb;
    color: #155724;
    border-radius: 6px;
    padding: 1rem;
}

/* =============================================
   BUTTONS
   ============================================= */
.btn {
    padding: 0.65rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 6px;
    transition: all 0.3s ease;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-navy), var(--secondary-navy));
    color: white;
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--secondary-navy), var(--primary-navy));
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(30, 58, 95, 0.3);
}

.btn-outline-light {
    border: 2px solid white;
    color: white;
}

.btn-outline-light:hover {
    background: white;
    color: var(--primary-navy);
    transform: translateY(-2px);
}

/* =============================================
   FOOTER
   ============================================= */
footer {
    background: linear-gradient(135deg, var(--primary-navy), var(--secondary-navy));
    color: white;
    padding: 3rem 0 1.5rem;
}

footer h5,
footer h6 {
    color: white;
    font-weight: 700;
    margin-bottom: 1rem;
}

footer p,
footer li {
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.9rem;
}

footer a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s ease;
}

/* =============================================
   BACK TO TOP BUTTON
   ============================================= */
.btn-back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--accent-gold);
    color: var(--primary-navy);
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(212, 175, 55, 0.3);
}

.btn-back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.btn-back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(212, 175, 55, 0.5);
    background: #c29d2f;
}

footer a:hover {
    color: var(--accent-gold);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    padding-top: 1.5rem;
    margin-top: 2rem;
    text-align: center;
}

/* =============================================
   UTILITY CLASSES
   ============================================= */
.text-primary {
    color: var(--primary-navy) !important;
}

.bg-primary {
    background: var(--primary-navy) !important;
}

.text-warning {
    color: var(--accent-gold) !important;
}

section {
    padding: 4rem 0;
}

.container {
    max-width: 1200px;
}

/* =============================================
   RESPONSIVE
   ============================================= */
@media (max-width: 992px) {
    .hero-title {
        font-size: 2.25rem;
    }

    .section-title {
        font-size: 1.85rem;
    }

    .navbar-collapse {
        background: linear-gradient(135deg, var(--primary-navy), var(--secondary-navy));
        padding: 1rem;
        margin-top: 1rem;
        border-radius: 8px;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    }

    .navbar-nav {
        gap: 0;
    }

    .nav-item {
        width: 100%;
    }

    .nav-link {
        padding: 0.75rem 1rem !important;
        width: 100%;
        text-align: left;
    }
}