:root {
    --bg: #1E1E1E;
    --bg-secondary: #2A2A2A;
    --text: #F2F2F2;
    --text-muted: #B8B8B8;
    --accent: #54D599;
    --accent-soft: rgba(84, 213, 153, 0.1);
    --border: #333333;
    --white: #FFFFFF;
    --error: #FF5F5F;
}

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

body {
    background-color: var(--bg);
    color: var(--text);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    overflow-x: hidden;
    scroll-behavior: smooth;
}

h1, h2, h3, h4 {
    color: var(--white);
    font-weight: 700;
    line-height: 1.2;
}

p {
    color: var(--text-muted);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header */
header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(30, 30, 30, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    color: #000000;
    letter-spacing: -0.05rem;
    text-decoration: none;
    text-shadow: 0 0 1px rgba(255,255,255,0.3);
}

.logo span {
    color: var(--accent);
    text-shadow: 0 0 15px rgba(84, 213, 153, 0.4);
}

.lang-switch {
    display: flex;
    gap: 1rem;
}

.lang-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: color 0.2s;
    text-transform: uppercase;
}

.lang-btn.active {
    color: var(--accent);
}

.lang-btn:hover {
    color: var(--white);
}

/* Hero */
.hero {
    padding: 10rem 0 6rem;
    display: flex;
    flex-direction: column;
    gap: 4rem;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-text {
    max-width: 600px;
}

.hero h1 {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    margin-bottom: 1.5rem;
    letter-spacing: -0.02em;
}

.hero p {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
}

.hero-visual {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 12px;
    aspect-ratio: 4/3;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    box-shadow: 0 20px 40px rgba(0,0,0,0.4);
}

/* Mockup elements */
.mock-line { height: 8px; background: var(--border); border-radius: 4px; width: 60%; }
.mock-node { width: 40px; height: 40px; background: var(--accent-soft); border: 1px solid var(--accent); border-radius: 8px; }

.btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    border-radius: 6px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    font-size: 1rem;
}

.btn-primary { background: var(--accent); color: var(--bg); }
.btn-primary:hover { opacity: 0.9; transform: translateY(-2px); }
.btn-secondary { background: transparent; color: var(--white); border: 1px solid var(--border); }
.btn-secondary:hover { background: var(--border); }

/* Sections */
section { padding: 8rem 0; }
.section-header { margin-bottom: 5rem; max-width: 700px; }
.section-header h2 { font-size: 2.5rem; margin-bottom: 1rem; }

/* Grid / Cards */
.grid-4 { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 2rem; }
.card { background: var(--bg-secondary); border: 1px solid var(--border); padding: 2.5rem; border-radius: 8px; transition: border-color 0.3s; }
.card:hover { border-color: var(--accent); }
.card h3 { margin-bottom: 1rem; font-size: 1.25rem; }
.card i { display: block; width: 40px; height: 40px; background: var(--accent-soft); border-radius: 6px; margin-bottom: 1.5rem; }

/* Problem Section */
.problem-item { border-bottom: 1px solid var(--border); padding: 2rem 0; display: flex; justify-content: space-between; align-items: flex-start; }
.problem-item h3 { font-size: 1.5rem; color: var(--text-muted); transition: color 0.3s; }
.problem-item:hover h3 { color: var(--white); }

/* Solution Visualization */
.solution-flow {
    margin-top: 4rem;
    padding: 4rem;
    background: linear-gradient(135deg, #2a2a2a 0%, #1e1e1e 100%);
    border: 1px solid var(--border);
    border-radius: 16px;
    text-align: center;
}

/* Use Cases */
.use-case-list { display: flex; flex-direction: column; gap: 4rem; }
.use-case { display: grid; grid-template-columns: 1fr 1fr; gap: 4rem; align-items: center; }
.use-case:nth-child(even) { direction: rtl; }
.use-case:nth-child(even) .use-case-text { direction: ltr; }

/* Form */
.form-section { background: var(--bg-secondary); }
.form-wrapper { max-width: 600px; margin: 0 auto; }
form { display: flex; flex-direction: column; gap: 1.5rem; }
.field { display: flex; flex-direction: column; gap: 0.5rem; }
.field label { font-size: 0.9rem; font-weight: 500; color: var(--white); }
input, select, textarea {
    background: var(--bg);
    border: 1px solid var(--border);
    padding: 1rem;
    border-radius: 6px;
    color: var(--white);
    font-family: inherit;
    font-size: 1rem;
    transition: border-color 0.2s;
}
input:focus, textarea:focus { border-color: var(--accent); outline: none; }
.error-msg { color: var(--error); font-size: 0.85rem; margin-top: 0.2rem; display: none; }
.success-overlay { text-align: center; display: none; }

/* Footer */
footer { padding: 4rem 0; border-top: 1px solid var(--border); text-align: center; }

/* Animations */
.fade-in { opacity: 0; transform: translateY(15px); transition: all 0.6s ease-out; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

@media (max-width: 968px) {
    .hero-content, .use-case { grid-template-columns: 1fr; gap: 3rem; }
    section { padding: 6rem 0; }
}