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

:root {
--primary: #1f6f54;
--primary-dark: #14523e;
--accent: #9fcfb9;
--dark: #0f2f24;
--gray: #5f7f73;
--light: #f4f9f7;
--border: #dbe7e1;
--white: #ffffff;
--shadow-soft: 0 14px 35px rgba(15,47,36,0.08);
--shadow-strong: 0 18px 40px rgba(15,47,36,0.25);
}

html {
scroll-behavior: smooth;
}

body {
font-family: system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
color: var(--dark);
line-height: 1.6;
background: var(--white);
}

a {
text-decoration: none;
color: inherit;
}

.container {
max-width: 1200px;
margin: auto;
padding: 0 1.5rem;
}

/* NAVBAR */
header {
border-bottom: 1px solid var(--border);
background: rgba(255,255,255,0.96);
backdrop-filter: blur(10px);
position: sticky;
top: 0;
z-index: 100;
}

.navbar {
display: flex;
justify-content: space-between;
align-items: center;
min-height: 72px;
gap: 1rem;
}

.logo {
font-size: 1.4rem;
font-weight: 800;
color: var(--primary);
letter-spacing: -0.02em;
}

.nav-links {
display: flex;
gap: 1.5rem;
color: var(--gray);
font-weight: 500;
flex-wrap: wrap;
}

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

/* HERO */
.hero {
min-height: 40vh;
padding: 4rem 0;
background: linear-gradient(135deg, var(--light), var(--white));
display: flex;
align-items: center;
}

.hero h1 {
font-size: clamp(2.4rem, 5vw, 3.8rem);
margin-bottom: 1rem;
line-height: 1.08;
max-width: 10ch;
}

.hero p {
color: var(--gray);
max-width: 650px;
font-size: 1.1rem;
}

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

.section-title {
text-align: center;
max-width: 750px;
margin: 0 auto 3.5rem;
}

.section-title h2 {
font-size: clamp(2rem, 4vw, 2.4rem);
margin-bottom: 0.75rem;
}

.section-title p {
color: var(--gray);
}

/* FEATURE GRID */
.feature-grid {
display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 2rem;
}

.feature-card {
background: var(--white);
border: 1px solid var(--border);
border-radius: 16px;
padding: 2.4rem;
transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
transform: translateY(-6px);
box-shadow: var(--shadow-soft);
}

.feature-icon {
width: 52px;
height: 52px;
border-radius: 12px;
background: linear-gradient(135deg, var(--primary), var(--primary-dark));
margin-bottom: 1rem;
}

.feature-card h3 {
margin-bottom: 0.5rem;
}

.feature-card p {
color: var(--gray);
}

/* DEEP FEATURE SECTIONS */
.feature-detail {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 4rem;
align-items: center;
}

.feature-detail-image {
height: 340px;
border-radius: 16px;
background: linear-gradient(135deg, #163c2f, #0f2f24);
color: var(--accent);
display: flex;
align-items: center;
justify-content: center;
font-weight: 600;
letter-spacing: 0.03em;
box-shadow: var(--shadow-strong);
}

.feature-detail h3 {
font-size: 2rem;
margin-bottom: 1rem;
}

.feature-detail p {
color: var(--gray);
margin-bottom: 1rem;
}

.reverse {
direction: rtl;
}

.reverse > * {
direction: ltr;
}

/* TOPICS */
.topics-section {
padding: 6rem 0;
background: var(--white);
}

.topics-layout {
display: grid;
grid-template-columns: 320px 1fr;
gap: 2rem;
align-items: stretch;
}

.topics-list {
display: flex;
flex-direction: column;
border-right: 1px solid var(--border);
padding-right: 1.5rem;
}

.topic-item {
display: flex;
flex-direction: column;
gap: 0.35rem;
padding: 1.25rem 0;
border-bottom: 1px solid var(--border);
color: var(--gray);
transition: color 0.25s ease, transform 0.25s ease;
}

.topic-item:hover,
.topic-item.active {
color: var(--primary);
transform: translateX(6px);
}

.topic-number {
font-size: 0.85rem;
font-weight: 700;
letter-spacing: 0.08em;
color: var(--accent);
}

.topic-name {
font-size: 1.3rem;
font-weight: 700;
line-height: 1.2;
}

.topics-preview {
position: relative;
min-height: 520px;
border-radius: 20px;
overflow: hidden;
background: #102e24;
box-shadow: 0 18px 40px rgba(15, 47, 36, 0.18);
}

.topic-panel {
position: absolute;
inset: 0;
background-size: cover;
background-position: center;
opacity: 0;
visibility: hidden;
transform: scale(1.02);
transition: opacity 0.45s ease, visibility 0.45s ease, transform 0.45s ease;
}

.topic-panel::before {
content: "";
position: absolute;
inset: 0;
background: linear-gradient(
180deg,
rgba(10,20,16,0.12) 0%,
rgba(10,20,16,0.36) 46%,
rgba(10,20,16,0.72) 100%
);
}

.topic-panel.active {
opacity: 1;
visibility: visible;
transform: scale(1);
}

.topic-overlay {
position: absolute;
left: 2rem;
right: 2rem;
bottom: 2rem;
max-width: 460px;
background: rgba(255,255,255,0.9);
backdrop-filter: blur(10px);
border: 1px solid rgba(255,255,255,0.5);
border-radius: 16px;
padding: 1.4rem 1.4rem 1.25rem;
box-shadow: 0 16px 34px rgba(0,0,0,0.12);
}

.topic-overlay h3 {
margin-bottom: 0.45rem;
font-size: 1.45rem;
color: var(--dark);
}

.topic-overlay p {
color: var(--gray);
margin: 0;
}

/* CTA */
.cta {
background: linear-gradient(135deg, #1f6f54, #14523e);
color: white;
text-align: center;
padding: 4.5rem 1.5rem;
border-radius: 18px;
max-width: 1000px;
margin: 4rem auto;
}

.cta p {
color: #d8efe6;
max-width: 600px;
margin: 0 auto 2rem;
}

.btn {
display: inline-block;
padding: 0.8rem 1.6rem;
border-radius: 6px;
font-weight: 600;
background: white;
color: var(--primary-dark);
transition: transform 0.2s ease, opacity 0.2s ease;
}

.btn:hover {
transform: translateY(-2px);
opacity: 0.96;
}

/* FOOTER */
footer {
border-top: 1px solid var(--border);
padding: 2rem 0;
color: var(--gray);
font-size: 0.9rem;
}

.footer-grid {
display: flex;
justify-content: space-between;
flex-wrap: wrap;
gap: 1rem;
}

/* RESPONSIVE */
@media (max-width: 900px) {
.feature-grid {
grid-template-columns: 1fr;
}

.feature-detail {
grid-template-columns: 1fr;
}

.hero h1 {
font-size: 2.4rem;
}

.navbar {
align-items: flex-start;
flex-direction: column;
padding: 0.75rem 0;
}

.topics-layout {
grid-template-columns: 1fr;
}

.topics-list {
border-right: 0;
padding-right: 0;
}

.topics-preview {
min-height: 400px;
}

.topic-overlay {
left: 1rem;
right: 1rem;
bottom: 1rem;
max-width: none;
}

.topic-name {
font-size: 1.1rem;
}
}


img {
    width: 100%;
    max-width: 700px;
}