@import url('https://fonts.googleapis.com/css2?family=Pretendard:wght@400;600;700;900&display=swap');

:root {
    --theme-bg: #f8fafc;
    --theme-text: #0f172a;
    --theme-primary: #3b82f6;
    --theme-card: #ffffff;
    --theme-radius: 12px;
    --theme-border: rgba(0,0,0,0.05);
    --theme-btn-text: #ffffff;
}

html, body {
    margin: 0; padding: 0; overflow-x: hidden;
    font-family: 'Pretendard', -apple-system, sans-serif;
    background: var(--theme-bg);
    color: var(--theme-text);
}

* { box-sizing: border-box; }
#rf-wrap { width: 100%; max-width: 100vw; overflow-x: hidden; }

.nav-header {
    position: sticky; top: 0; z-index: 100;
    padding: 1rem 3rem;
    display: flex; justify-content: space-between; align-items: center;
    background: rgba(255,255,255,0.85);
    border-bottom: 1px solid var(--theme-border);
    backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.05);
}
.nav-logo { font-weight: 900; font-size: 1.4rem; color: var(--theme-text); text-decoration: none; display: flex; align-items: center; letter-spacing: -0.03em; }
.nav-logo .logo-accent { color: var(--theme-primary); }

/* Common Buttons */
.btn-group { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }
.btn {
    padding: 1rem 2rem; border-radius: var(--theme-radius);
    font-weight: 700; text-decoration: none; font-size: 1.05rem;
    transition: all 0.2s; display: inline-flex; align-items: center; gap: 0.5rem;
}
.btn-primary { background: var(--theme-primary); color: var(--theme-btn-text); }
.btn-primary:hover { transform: translateY(-3px); box-shadow: 0 10px 20px -5px var(--theme-primary); }
.btn-outline { border: 2px solid var(--theme-primary); color: var(--theme-primary); background: transparent; }
.btn-outline:hover { background: #3b82f615; }

.footer { padding: 5rem 2rem; border-top: 1px solid var(--theme-border); font-size: 0.95rem; background: rgba(0,0,0,0.02); }
.footer-container { max-width: 1200px; margin: 0 auto; display: flex; flex-direction: column; gap: 1.5rem; }
.footer-logo { opacity: 0.7; font-size:1.4rem; font-weight:900; letter-spacing:-0.03em; display:flex; align-items:center; }
.footer-links { display: flex; gap: 2rem; flex-wrap: wrap; }
.footer-links a { color: var(--theme-text); text-decoration: none; font-weight: 600; opacity: 0.7; transition: opacity 0.2s; }
.footer-links a:hover { opacity: 1; text-decoration: underline; }
.footer-info { opacity: 0.5; line-height: 1.7; }

/* Common Content Sections (Timeline, Topics, CTA) */
.section-title { font-size: 2.2rem; font-weight: 900; text-align: center; margin-bottom: 3rem; letter-spacing: -0.03em; }
.timeline-section { padding: 6rem 2rem; background: rgba(0,0,0,0.02); border-top: 1px solid var(--theme-border); border-bottom: 1px solid var(--theme-border); }
.timeline-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 2rem; max-width: 1200px; margin: 0 auto; }
.timeline-step { padding: 2.5rem 2rem; background: var(--theme-card); border-radius: var(--theme-radius); border: 1px solid var(--theme-border); position: relative; transition: all 0.3s; }
.timeline-step:hover { transform: translateY(-5px); border-color: var(--theme-primary); }
.timeline-step.active { border: 2px solid var(--theme-primary); box-shadow: 0 15px 30px -10px var(--theme-primary); }
.step-num { font-size: 3rem; font-weight: 900; color: var(--theme-primary); opacity: 0.2; position: absolute; top: 1rem; right: 1.5rem; }
.timeline-step h4 { font-size: 1.3rem; font-weight: 700; margin: 0 0 1rem; position: relative; z-index: 2; }
.timeline-step p { opacity: 0.8; line-height: 1.6; margin: 0; position: relative; z-index: 2; }

.topics-section { padding: 6rem 2rem; max-width: 1200px; margin: 0 auto; }
.topics-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.5rem; }
.topic-card { padding: 2rem; background: var(--theme-card); border-radius: var(--theme-radius); border: 1px solid var(--theme-border); transition: 0.2s; }
.topic-card:hover { background: #3b82f610; border-color: var(--theme-primary); }
.topic-card h4 { font-size: 1.2rem; font-weight: 700; margin: 0 0 0.8rem; color: var(--theme-primary); }
.topic-card p { opacity: 0.8; line-height: 1.6; margin: 0; }

.cta-banner { padding: 6rem 2rem; text-align: center; background: linear-gradient(135deg, var(--theme-bg), var(--theme-card)); border-top: 1px solid var(--theme-border); }
.cta-banner h2 { font-size: clamp(2rem, 4vw, 3rem); font-weight: 900; margin: 0 0 1rem; }
.cta-banner p { font-size: 1.2rem; opacity: 0.8; margin-bottom: 2rem; }

.hero { padding: 8rem 2rem; text-align: center; background: var(--theme-bg); }
.hero-tag { display: inline-block; padding: 0.5rem 1rem; border-radius: 50px; background: var(--theme-border); font-weight: 700; font-size: 0.85rem; margin-bottom: 2rem; color: var(--theme-primary); }
.hero h1 { font-size: clamp(2.5rem, 6vw, 4.5rem); font-weight: 900; line-height: 1.2; margin: 0 0 1.5rem; letter-spacing: -0.04em; }
.hero p { font-size: 1.2rem; line-height: 1.6; max-width: 650px; margin: 0 auto 3rem; opacity: 0.8; }
.features { padding: 0 2rem 6rem; max-width: 1200px; margin: 0 auto; }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 2rem; margin-top: -3rem; position: relative; z-index: 10; }
.card { background: var(--theme-card); padding: 3rem 2rem; border-radius: var(--theme-radius); text-decoration: none; color: inherit; border: 1px solid var(--theme-border); box-shadow: 0 10px 30px rgba(0,0,0,0.05); transition: all 0.3s; }
.card:hover { transform: translateY(-8px); border-color: var(--theme-primary); }
.card-icon { width: 60px; height: 60px; border-radius: 16px; background: var(--theme-primary); color: var(--theme-btn-text); display: flex; align-items: center; justify-content: center; margin-bottom: 1.5rem; font-size: 1.5rem; }
.card h3 { font-size: 1.6rem; font-weight: 800; margin: 0 0 1rem; }
.card p { opacity: 0.7; line-height: 1.6; margin: 0; font-size: 1.05rem; }