:root {
    --bg-light: #f8fafc;
    --card-bg: rgba(255, 255, 255, 0.7);
    --primary: #2ecc71;
    --primary-dark: #27ae60;
    --secondary: #3498db;
    --text-dark: #1a2a3a;
    --text-muted: #4a627a;
    --border-light: rgba(0, 0, 0, 0.08);
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.05);
    --gradient: linear-gradient(135deg, #2ecc71, #3498db);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
}

/* ─── Scroll Progress Bar ─── */
.scroll-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 3px;
    width: 0%;
    background: var(--gradient);
    z-index: 9999;
    border-radius: 0 2px 2px 0;
    transition: width 0.1s linear;
    box-shadow: 0 0 8px rgba(46, 204, 113, 0.5);
}

/* ─── Navbar ─── */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(12px);
    z-index: 1000;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-light);
    box-shadow: 0 2px 10px rgba(0,0,0,0.02);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 90%;
    margin: 0 auto;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-decoration: none;
}

.nav-menu {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-link {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

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

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    margin: 3px 0;
    transition: 0.3s;
}

/* ─── Hero: Split Layout ─── */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: stretch;
    overflow: hidden;
    position: relative;
}

/* Left panel */
.hero-left {
    flex: 0 0 50%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 8rem 4rem 6rem 7%;
    background: linear-gradient(160deg, #f0fdf6 0%, #e8f4fd 60%, #eef5ff 100%);
    position: relative;
    z-index: 2;
}

/* Decorative separator between halves */
.hero-left::after {
    content: '';
    position: absolute;
    right: 0;
    top: 0;
    height: 100%;
    width: 1px;
    background: linear-gradient(to bottom, transparent, rgba(46,204,113,0.3) 30%, rgba(52,152,219,0.3) 70%, transparent);
}

/* Hero eyebrow badge */
.hero-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--primary-dark);
    background: rgba(46, 204, 113, 0.1);
    border: 1px solid rgba(46, 204, 113, 0.25);
    border-radius: 40px;
    padding: 6px 14px;
    margin-bottom: 1.6rem;
    width: fit-content;
    animation: fadeSlideDown 0.6s ease both;
}

.eyebrow-pulse {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--primary);
    display: inline-block;
    position: relative;
    animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
    0%, 100% { box-shadow: 0 0 0 0 rgba(46, 204, 113, 0.5); }
    50% { box-shadow: 0 0 0 5px rgba(46, 204, 113, 0); }
}

@keyframes fadeSlideDown {
    from { opacity: 0; transform: translateY(-12px); }
    to   { opacity: 1; transform: translateY(0); }
}

.glow-text {
    font-size: clamp(2.2rem, 3.5vw, 3.6rem);
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 1.2rem;
    color: var(--text-dark);
    animation: fadeSlideUp 0.7s 0.1s ease both;
}

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

.hero-desc {
    font-size: 1.1rem;
    color: var(--text-muted);
    max-width: 440px;
    margin-bottom: 2.2rem;
    line-height: 1.75;
    animation: fadeSlideUp 0.7s 0.2s ease both;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    animation: fadeSlideUp 0.7s 0.3s ease both;
}

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

/* ─── Right side: Earth ─── */
#earth-container {
    flex: 0 0 50%;
    height: 100vh;
    position: relative;
}

/* ─── Scroll Down Cue ─── */
.scroll-down-cue {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
    margin-top: 3rem;
    animation: fadeSlideUp 0.7s 0.5s ease both;
}

.scroll-cue-text {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--text-muted);
}

.scroll-mouse-wrap {
    display: flex;
    align-items: center;
}

.scroll-mouse {
    width: 22px;
    height: 36px;
    border: 2px solid var(--primary);
    border-radius: 12px;
    position: relative;
    display: flex;
    justify-content: center;
    padding-top: 5px;
}

.scroll-wheel {
    width: 4px;
    height: 8px;
    background: var(--primary);
    border-radius: 2px;
    animation: scroll-wheel-anim 1.8s ease-in-out infinite;
}

@keyframes scroll-wheel-anim {
    0%   { transform: translateY(0); opacity: 1; }
    60%  { transform: translateY(10px); opacity: 0; }
    61%  { transform: translateY(0); opacity: 0; }
    100% { transform: translateY(0); opacity: 1; }
}

.scroll-cue-arrows {
    display: flex;
    flex-direction: column;
    gap: 3px;
    align-items: flex-start;
}

.scroll-cue-arrows span {
    display: block;
    width: 10px;
    height: 10px;
    border-right: 2px solid var(--primary);
    border-bottom: 2px solid var(--primary);
    transform: rotate(45deg);
    animation: cue-arrow-fade 1.8s ease-in-out infinite;
}

.scroll-cue-arrows span:nth-child(1) { animation-delay: 0s; }
.scroll-cue-arrows span:nth-child(2) { animation-delay: 0.2s; }
.scroll-cue-arrows span:nth-child(3) { animation-delay: 0.4s; }

@keyframes cue-arrow-fade {
    0%, 100% { opacity: 0.2; }
    50% { opacity: 1; }
}

/* ─── Section Divider Hints ─── */
.section-divider-hint {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    padding: 2rem 0 1rem;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.7s ease, transform 0.7s ease;
}

.section-divider-hint.revealed {
    opacity: 1;
    transform: translateY(0);
}

.divider-inner {
    display: flex;
    align-items: center;
    gap: 1.2rem;
    width: 100%;
    max-width: 600px;
    padding: 0 2rem;
}

.divider-line {
    flex: 1;
    height: 1px;
    background: linear-gradient(to right, transparent, rgba(46, 204, 113, 0.4), transparent);
}

.divider-label {
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--primary-dark);
    white-space: nowrap;
}

.divider-arrow {
    color: var(--primary);
    animation: bounce-arrow 2s ease-in-out infinite;
}

.divider-arrow svg {
    display: block;
}

@keyframes bounce-arrow {
    0%, 100% { transform: translateY(0); opacity: 0.6; }
    50% { transform: translateY(6px); opacity: 1; }
}

/* ─── Buttons ─── */
.btn {
    display: inline-block;
    padding: 12px 32px;
    border-radius: 40px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: var(--gradient);
    color: white;
    box-shadow: 0 4px 15px rgba(46, 204, 113, 0.3);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(46, 204, 113, 0.4);
}

.btn-outline {
    background: transparent;
    color: var(--primary-dark);
    border: 2px solid var(--primary);
}

.btn-outline:hover {
    background: rgba(46, 204, 113, 0.08);
    transform: translateY(-3px);
}

/* ─── Sections ─── */
.section {
    padding: 5rem 0;
}

.section-label {
    display: inline-block;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--primary-dark);
    margin-bottom: 0.8rem;
    opacity: 0.7;
}

.section-title {
    text-align: center;
    font-size: clamp(1.8rem, 3vw, 2.5rem);
    margin-bottom: 3rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.section .section-label {
    display: block;
    text-align: center;
}

/* ─── Cards ─── */
.problems-grid, .tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.problem-card, .tip-card, .fact-card {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: 20px;
    border: 1px solid var(--border-light);
    transition: transform 0.3s, box-shadow 0.3s;
    box-shadow: var(--shadow);
}

.problem-card:hover, .tip-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 40px rgba(0,0,0,0.1);
}

.problem-icon, .tip-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.progress-bar {
    background: #e0e7ff;
    border-radius: 10px;
    height: 10px;
    margin-top: 10px;
    overflow: hidden;
}

.progress-fill {
    background: var(--gradient);
    width: 0%;
    height: 100%;
    border-radius: 10px;
    transition: width 1.2s cubic-bezier(0.2, 0.8, 0.3, 1);
}

/* Staggered animation delays for grid cards */
.problems-grid .fade-up:nth-child(1),
.tips-grid .fade-up:nth-child(1) { transition-delay: 0s; }
.problems-grid .fade-up:nth-child(2),
.tips-grid .fade-up:nth-child(2) { transition-delay: 0.1s; }
.problems-grid .fade-up:nth-child(3),
.tips-grid .fade-up:nth-child(3) { transition-delay: 0.2s; }
.problems-grid .fade-up:nth-child(4),
.tips-grid .fade-up:nth-child(4) { transition-delay: 0.3s; }

.facts-list .fade-up:nth-child(1) { transition-delay: 0s; }
.facts-list .fade-up:nth-child(2) { transition-delay: 0.12s; }
.facts-list .fade-up:nth-child(3) { transition-delay: 0.24s; }
.facts-list .fade-up:nth-child(4) { transition-delay: 0.36s; }

/* ─── Facts ─── */
.facts-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.fact-card {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.fact-card:hover {
    transform: translateX(10px);
}

.fact-number {
    font-size: 2.5rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    flex-shrink: 0;
}

/* ─── CTA ─── */
.cta-section {
    padding: 4rem 0;
}

.cta-card {
    background: linear-gradient(135deg, rgba(46, 204, 113, 0.1), rgba(52, 152, 219, 0.1));
    backdrop-filter: blur(10px);
    padding: 3rem;
    border-radius: 40px;
    text-align: center;
    border: 1px solid rgba(46, 204, 113, 0.3);
    max-width: 800px;
    margin: 0 auto;
    transition: transform 0.3s;
}

.cta-card:hover {
    transform: scale(1.02);
}

.cta-card h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.cta-card p {
    margin-bottom: 2rem;
    font-size: 1.2rem;
    color: var(--text-muted);
}

.btn-large {
    padding: 16px 48px;
    font-size: 1.2rem;
    border-radius: 60px;
    background: var(--gradient);
    color: white;
    box-shadow: 0 8px 20px rgba(46, 204, 113, 0.4);
    transition: all 0.3s;
}

.btn-large:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 28px rgba(46, 204, 113, 0.5);
}

/* ─── Calculator ─── */
.calculator-section {
    padding: 4rem 0;
}

.calculator-card {
    max-width: 600px;
    margin: 0 auto;
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: 30px;
    box-shadow: var(--shadow);
}

.result-area {
    margin-top: 2rem;
    text-align: center;
}

.co2-number {
    font-size: 3.5rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin: 1rem 0;
}

.co2-number span {
    font-size: 1.2rem;
    color: var(--text-muted);
}

.recommendation, .comparison {
    background: rgba(0,0,0,0.02);
    padding: 1rem;
    border-radius: 12px;
    margin: 1rem 0;
    border: 1px solid var(--border-light);
}

/* ─── Contact form ─── */
.contact-form-section .container {
    max-width: 600px;
    margin: 0 auto;
}

.glass-form {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: 30px;
    box-shadow: var(--shadow);
}

.form-group {
    margin-bottom: 1.5rem;
}

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

input, textarea {
    width: 100%;
    padding: 12px 20px;
    background: white;
    border: 1px solid var(--border-light);
    border-radius: 12px;
    color: var(--text-dark);
    font-size: 1rem;
    transition: 0.3s;
}

input:focus, textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(46, 204, 113, 0.1);
}

.form-message {
    margin-top: 1rem;
    text-align: center;
    font-weight: 500;
}

/* ─── Footer ─── */
.footer {
    background: #ffffff;
    text-align: center;
    padding: 2rem 0;
    margin-top: 4rem;
    border-top: 1px solid var(--border-light);
    color: var(--text-muted);
}

.social-links a {
    color: var(--text-muted);
    margin: 0 10px;
    font-size: 1.5rem;
    text-decoration: none;
    transition: color 0.3s;
}

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

/* ─── Page header ─── */
.page-header {
    padding: 8rem 0 3rem;
    text-align: center;
    background: linear-gradient(135deg, rgba(46, 204, 113, 0.05), rgba(52, 152, 219, 0.05));
}

/* ─── Responsive ─── */
@media (max-width: 900px) {
    .hero {
        flex-direction: column;
        min-height: 100vh;
        position: relative;
    }

    .hero-left {
        flex: none;
        width: 100%;
        min-height: 100vh;
        padding: 7rem 1.5rem 5rem;
        background: linear-gradient(160deg, rgba(240,253,246,0.92) 0%, rgba(232,244,253,0.92) 100%);
        align-items: center;
        text-align: center;
    }

    .hero-left::after {
        display: none;
    }

    .hero-eyebrow {
        align-self: center;
    }

    .hero-desc {
        max-width: 100%;
    }

    .hero-actions {
        justify-content: center;
    }

    .scroll-down-cue {
        align-items: center;
    }

    #earth-container {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        flex: none;
        opacity: 0.18;
        z-index: 0;
    }

    .hero-left {
        position: relative;
        z-index: 1;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(10px);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        padding: 2rem 0;
        box-shadow: 0 10px 20px rgba(0,0,0,0.05);
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

    .glow-text {
        font-size: 2.2rem;
    }
}

.fade-up {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.75s cubic-bezier(0.2, 0.9, 0.3, 1),
                transform 0.75s cubic-bezier(0.2, 0.9, 0.3, 1);
}

.fade-up.visible {
    opacity: 1;
    transform: translateY(0);
}

.eco-card {
    padding: 45px 60px;
    border-radius: 20px;

    border: 2px solid transparent;
    background: 
        linear-gradient(#fff, #fff) padding-box,
        linear-gradient(135deg, #00ff87, #2ecc71, #27ae60) border-box;

    max-width: 500px;
    width: 100%;
    text-align: center;

    transition: all 0.3s ease;
}

.eco-card h2 {
    color: #555;
    margin-bottom: 15px;
    font-size: 26px;
}

.eco-card p {
    color: #777;
    font-size: 18px;
    line-height: 1.6;
}

.eco-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 18px 45px rgba(0, 255, 135, 0.25);
}