*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
:root {
    --bg: #fafaf9; --surface: #fff; --text: #1c1917; --text-2: #78716c; --text-3: #a8a29e;
    --border: #e7e5e4; --accent: #0f766e; --accent-light: #f0fdfa; --error: #dc2626;
    --dark-bg: #0a0a0a; --dark-text: #e7e5e4; --dark-border: #262626;
}
body { font-family: 'DM Sans', 'Noto Sans SC', sans-serif; background: var(--bg); color: var(--text); min-height: 100vh; }

/* Header */

header { padding: 1rem 1.5rem; display: flex; justify-content: space-between; align-items: center; border-bottom: 1px solid var(--border); background: var(--surface); position: fixed; top: 0; left: 0; right: 0; z-index: 100; }
.logo { display: flex; flex-direction: column; align-items: flex-start; line-height: 1; }
.logo-main { font-size: 1.5rem; font-weight: 700; background: linear-gradient(135deg, #0f766e 0%, #14b8a6 25%, #0d9488 50%, #0f766e 75%, #134e4a 100%); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; letter-spacing: -.005em; }
.logo-sub { font-size: .7rem; font-weight: 600; color: var(--text); text-transform: uppercase; letter-spacing: .15em; margin-top: .25rem; }
.lang-toggle { font-size: .875rem; color: var(--text-2); cursor: pointer; padding: .5rem 1rem; border: 1px solid var(--border); border-radius: 6px; background: transparent; transition: all .2s; }
.lang-toggle:hover { border-color: var(--accent); color: var(--accent); }
/* Hero Section */
.hero-container { min-height: 100vh; display: grid; grid-template-columns: 1fr 1fr; padding-top: 60px; }

/* Left: Auth */
.auth-side { display: flex; flex-direction: column; justify-content: center; padding: 4rem 3rem 4rem 4rem; border-right: 1px solid var(--border); background: var(--surface); }
.auth-content { max-width: 440px; }
.auth-title { font-size: 2rem; font-weight: 600; margin-bottom: 1.5rem; letter-spacing: -.03em; }
.auth-subtitle { color: var(--text-2); margin-bottom: 2rem; line-height: 1.6; }
.auth-form { display: flex; flex-direction: column; gap: 1rem; }
.form-group { display: flex; flex-direction: column; gap: .5rem; }
.form-label { font-size: .875rem; font-weight: 500; color: var(--text-2); }
.form-input { padding: .875rem; border: 1px solid var(--border); border-radius: 6px; font: inherit; background: var(--bg); transition: border-color .2s; }
.form-input:focus { outline: none; border-color: var(--accent); }
.form-input.error { border-color: var(--error); }
.error-msg { color: var(--error); font-size: .875rem; margin-top: -.5rem; display: none; }
.error-msg.show { display: block; }
.submit-btn { background: var(--accent); color: #fff; padding: .875rem; border-radius: 6px; border: none; font: inherit; font-weight: 500; cursor: pointer; transition: background .2s; }
.submit-btn:hover { background: #0d635c; }
.toggle-text { text-align: center; margin-top: 1rem; font-size: .875rem; color: var(--text-2); }
.toggle-link { color: var(--accent); cursor: pointer; text-decoration: none; }
.toggle-link:hover { text-decoration: underline; }
.password-wrapper { position: relative; }
.password-toggle { position: absolute; right: .875rem; top: 50%; transform: translateY(-50%); background: none; border: none; cursor: pointer; color: var(--text-3); padding: 0; width: 20px; height: 20px; display: flex; align-items: center; justify-content: center; }
.password-toggle:hover { color: var(--text-2); }
.password-toggle svg { width: 18px; height: 18px; }

/* Right: Demo */
.demo-side { display: flex; flex-direction: column; justify-content: center; align-items: center; padding: 4rem; background: url('https://images.unsplash.com/photo-1578575437130-527eed3abbec?w=1200&q=80') center/cover; position: relative; }
.demo-side::before { content: ''; position: absolute; inset: 0; background: linear-gradient(135deg, rgba(250,249,249,.80) 0%, rgba(250,249,249,.92) 100%); }
.demo-content { max-width: 100%; width: 100%; position: relative; z-index: 1; }
.demo-window { background: var(--surface); border-radius: 12px; border: 1px solid var(--border); box-shadow: 0 4px 24px rgba(0,0,0,.04); padding: .75rem 1rem; }
.input-wrapper { display: flex; gap: .75rem; align-items: center; min-height: 36px; }
.input-field { flex: 1; position: relative; display: flex; align-items: center; }
.typewriter-overlay { position: absolute; inset: 0; font-size: 1rem; line-height: 1.5; color: var(--text-3); font-style: italic; pointer-events: none; display: flex; align-items: center; }
.typewriter-cursor { width: 2px; height: 1.2em; background: var(--accent); margin-left: 1px; animation: blink 1s infinite; }
@keyframes blink { 0%, 50% { opacity: 1; } 51%, 100% { opacity: 0; } }
textarea { width: 100%; border: none; font: inherit; font-size: 1rem; resize: none; min-height: 24px; line-height: 1.5; background: transparent; color: var(--text); cursor: default; }
textarea:focus { outline: none; }
.send-btn { width: 36px; height: 36px; border-radius: 8px; border: none; background: var(--accent); color: #fff; cursor: pointer; display: flex; align-items: center; justify-content: center; transition: all .2s; flex-shrink: 0; }
.send-btn:hover { background: #0d635c; }
.send-btn svg { width: 18px; height: 18px; }

/* Slogans */
.slogan-section { min-height: 100vh; display: flex; align-items: center; padding: 2rem; }
.slogan-section.left { justify-content: flex-start; }
.slogan-section.right { justify-content: flex-end; }
.slogan-wrapper { max-width: 900px; padding: 0 4rem; }
.slogan { font-size: clamp(3rem, 8vw, 6rem); font-weight: 600; letter-spacing: -.03em; line-height: 1.1; }
.slogan[lang="zh"] { font-size: clamp(3rem, 8vw, 5.5rem); line-height: 1.25; }
.slogan .word { display: inline-block; white-space: nowrap; }
.slogan .word .char { display: inline-block; opacity: .12; color: var(--text); transition: opacity .1s; }
.slogan .word .char.active { opacity: 1; background: linear-gradient(135deg, var(--accent) 0%, #0d9488 100%); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.slogan .word::after { content: ' '; }

/* Process Section */
.process-section { padding: 8rem 2rem; background: var(--surface); position: relative; overflow: hidden; }
.process-section::before { content: ''; position: absolute; inset: 0; background: url('https://images.unsplash.com/photo-1578575437130-527eed3abbec?w=1600&q=80') center/cover; opacity: .08; }
.process-container { max-width: 1100px; margin: 0 auto; position: relative; z-index: 1; }
.process-title { font-size: 2.5rem; font-weight: 600; text-align: center; margin-bottom: 1rem; letter-spacing: -.03em; }
.process-subtitle { text-align: center; color: var(--text-2); max-width: 600px; margin: 0 auto 5rem; font-size: 1.125rem; }
.process-flow { position: relative; }
.flow-item { display: grid; grid-template-columns: 60px 1fr; gap: 2.5rem; margin-bottom: 3.5rem; position: relative; padding-left: 1rem; }
.flow-item:not(:last-child)::after { content: ''; position: absolute; left: 30px; top: 50px; bottom: -3.5rem; width: 2px; background: var(--border); }
.flow-number { width: 40px; height: 40px; display: flex; align-items: center; justify-content: center; font-size: 1.25rem; font-weight: 700; color: var(--accent); flex-shrink: 0; }
.flow-content { padding-top: .25rem; }
.flow-label { font-size: .75rem; text-transform: uppercase; letter-spacing: .1em; color: var(--text-3); font-weight: 600; margin-bottom: .5rem; }
.flow-title { font-size: 1.75rem; font-weight: 600; margin-bottom: 1rem; }
.flow-description { color: var(--text-2); line-height: 1.7; max-width: 600px; }
.cta-container { text-align: center; padding-top: 3rem; }
.learn-more { display: inline-flex; align-items: center; gap: .5rem; color: var(--accent); text-decoration: none; font-weight: 500; font-size: .9375rem; transition: gap .2s; }
.learn-more:hover { gap: .75rem; }

/* Footer */
footer { background: var(--dark-bg); color: var(--dark-text); padding: 4rem 0 2rem; }
.footer-content { max-width: 1200px; margin: 0 auto; padding: 0 2rem; display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 4rem; }
.footer-section h3 { font-size: .875rem; font-weight: 600; margin-bottom: 1.5rem; color: var(--dark-text); text-transform: uppercase; letter-spacing: .05em; }
.footer-section ul { list-style: none; }
.footer-section li { margin-bottom: .75rem; }
.footer-section a { color: #a8a29e; text-decoration: none; font-size: .9375rem; transition: color .2s; }
.footer-section a:hover { color: var(--accent); }
.footer-section p { color: #a8a29e; font-size: .9375rem; line-height: 1.7; }
.footer-bottom { max-width: 1200px; margin: 3rem auto 0; padding: 2rem 2rem 0; border-top: 1px solid var(--dark-border); text-align: center; color: #78716c; font-size: .875rem; }

/* Mobile */

@media (max-width: 968px) {
    body { display: flex !important; flex-direction: column !important; }
    .hero-container { grid-template-columns: 1fr; display: flex; flex-direction: column; order: 1; }
    .demo-side { padding: 3rem 2rem; min-height: 100vh; order: 1; }
    .auth-side { border-right: none; border-bottom: 1px solid var(--border); padding: 3rem 2rem; display: flex; align-items: center; justify-content: center; order: 2; }
    .auth-content { width: 100%; }
    .slogan-section { order: 2; }
    .process-section { order: 3; }
    footer { order: 4; }
    header { order: 0; }
    .slogan { font-size: clamp(2.5rem, 10vw, 4rem) !important; }
    .slogan-wrapper { padding: 0 2rem; }
    .slogan-section.left, .slogan-section.right { justify-content: center; }
    .flow-item { grid-template-columns: 40px 1fr; gap: 1.5rem; padding-left: 0; }
    .flow-number { width: 32px; height: 32px; font-size: 1rem; }
    .flow-item:not(:last-child)::after { left: 20px; }
    .flow-title { font-size: 1.5rem; }
    .footer-content { grid-template-columns: 1fr; gap: 2rem; }
}