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

:root {
    /* Telegram-inspired palette */
    --primary: #0088cc;
    --primary-dark: #0077aa;
    --accent: #31a24c;
    --text-primary: #000000;
    --text-secondary: #656565;
    --text-tertiary: #a0a0a0;
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #efefef;
    --border: #dadada;
    --border-light: #e8e8e8;
    --success: #31a24c;
    --error: #dd483b;
    --warning: #f9a825;

    /* Project ecosystem accents */
    --otpLogin-accent: #0088cc;
    --tggo-accent: #9945ff;
    --tgdrive-accent: #1db446;
    --storetg-accent: #ff6b35;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    color: var(--text-primary);
    background: var(--bg-primary);
    line-height: 1.5;
    letter-spacing: 0.3px;
}

.container {
    max-width: 980px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    border-bottom: 1px solid var(--border-light);
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg-primary);
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.95);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 0;
}

.logo {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.logo-icon {
    display: inline-block;
    width: 24px;
    height: 24px;
    background: var(--otpLogin-accent);
    border-radius: 6px;
    margin-right: 8px;
    vertical-align: middle;
}

.nav {
    display: flex;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    border-radius: 6px;
    transition: all 0.2s;
    cursor: pointer;
    border: none;
    background: transparent;
}

.nav-link:hover {
    color: var(--text-primary);
    background: var(--bg-secondary);
}

.nav-link.active {
    color: var(--otpLogin-accent);
    font-weight: 600;
}

@media (max-width: 640px) {
    .nav {
        gap: 4px;
    }

    .nav-link {
        padding: 8px 12px;
        font-size: 13px;
    }
}

/* Hero */
.hero {
    padding: 80px 0 60px;
    text-align: center;
}

.hero h1 {
    font-size: clamp(32px, 6vw, 52px);
    font-weight: 700;
    margin-bottom: 12px;
    line-height: 1.2;
    letter-spacing: -0.5px;
}

.hero .tagline {
    font-size: 18px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-weight: 500;
}

.hero .description {
    font-size: 15px;
    color: var(--text-tertiary);
    max-width: 480px;
    margin: 16px auto 32px;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Buttons */
button, .btn {
    padding: 10px 24px;
    border: none;
    border-radius: 6px;
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    display: inline-block;
    text-align: center;
    letter-spacing: 0.2px;
}

.btn-primary {
    background: var(--otpLogin-accent);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 136, 204, 0.3);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    border-color: var(--border);
}

.btn-outline {
    background: transparent;
    color: var(--otpLogin-accent);
    border: 1px solid var(--border-light);
}

.btn-outline:hover {
    background: var(--bg-secondary);
}

/* Sections */
section {
    padding: 60px 0;
    border-top: 1px solid var(--border-light);
}

section h2 {
    font-size: clamp(20px, 4vw, 32px);
    font-weight: 700;
    margin-bottom: 40px;
    text-align: center;
    letter-spacing: -0.3px;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 20px;
}

.feature-card {
    padding: 24px;
    background: var(--bg-secondary);
    border-radius: 8px;
    border: 1px solid var(--border-light);
    transition: all 0.2s;
}

.feature-card:hover {
    border-color: var(--otpLogin-accent);
    background: var(--bg-primary);
    box-shadow: 0 2px 8px rgba(0, 136, 204, 0.1);
}

.feature-card h3 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.feature-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
}

.feature-icon {
    font-size: 24px;
    margin-bottom: 12px;
}

/* Problem/Solution */
.comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    margin-bottom: 40px;
}

.comparison-card {
    padding: 28px;
    border-radius: 8px;
    border: 1px solid var(--border-light);
}

.comparison-card.bad {
    background: rgba(221, 72, 59, 0.05);
    border-color: rgba(221, 72, 59, 0.2);
}

.comparison-card.good {
    background: rgba(49, 162, 76, 0.05);
    border-color: rgba(49, 162, 76, 0.2);
}

.comparison-card h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.comparison-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
}

@media (max-width: 640px) {
    .comparison {
        grid-template-columns: 1fr;
    }
}

/* Demo Section */
.demo-section {
    background: var(--bg-secondary);
    border-radius: 8px;
    padding: 40px;
    border: 1px solid var(--border-light);
}

.demo-step {
    margin-bottom: 32px;
}

.demo-step:last-child {
    margin-bottom: 0;
}

.demo-step h3 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.demo-step p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.code-input-group {
    display: flex;
    gap: 8px;
    margin-bottom: 12px;
    justify-content: center;
}

.code-digit {
    width: 44px;
    height: 44px;
    font-size: 20px;
    font-weight: 600;
    text-align: center;
    border: 1px solid var(--border);
    border-radius: 6px;
    transition: all 0.2s;
    background: var(--bg-primary);
    color: var(--text-primary);
}

.code-digit:focus {
    border-color: var(--otpLogin-accent);
    outline: none;
    box-shadow: 0 0 0 2px rgba(0, 136, 204, 0.1);
}

.code-digit.filled {
    background: var(--otpLogin-accent);
    color: white;
    border-color: var(--otpLogin-accent);
}

.json-output {
    background: var(--bg-primary);
    border: 1px solid var(--border-light);
    padding: 16px;
    border-radius: 6px;
    font-family: 'Monaco', 'Menlo', monospace;
    font-size: 12px;
    color: var(--text-secondary);
    overflow-x: auto;
    white-space: pre;
    overflow-y: auto;
    line-height: 1.5;
}

.json-key {
    color: var(--otpLogin-accent);
}

.json-string {
    color: var(--success);
}

.json-number {
    color: var(--warning);
}

/* Integration Steps */
.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 24px;
}

.step {
    position: relative;
    padding-left: 50px;
}

.step-number {
    position: absolute;
    left: 0;
    top: 0;
    width: 36px;
    height: 36px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    color: var(--otpLogin-accent);
    font-size: 16px;
}

.step h3 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.step p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* CTA Section */
.cta-section {
    background: var(--bg-secondary);
    padding: 60px 40px;
    border-radius: 8px;
    border: 1px solid var(--border-light);
    text-align: center;
}

.cta-section h2 {
    border-top: none;
    margin-top: 0;
    margin-bottom: 24px;
}

.form-group {
    margin-bottom: 16px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-primary);
    text-align: left;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 14px;
    font-family: inherit;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all 0.2s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--otpLogin-accent);
    box-shadow: 0 0 0 2px rgba(0, 136, 204, 0.1);
}

.form-inline {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

@media (max-width: 640px) {
    .form-inline {
        grid-template-columns: 1fr;
    }

    .demo-section {
        padding: 24px;
    }

    .cta-section {
        padding: 40px 20px;
    }
}

/* Alerts */
.alert {
    padding: 12px 16px;
    border-radius: 6px;
    margin-bottom: 16px;
    display: none;
    font-size: 14px;
    border: 1px solid;
}

.alert.show {
    display: block;
}

.alert-success {
    background: rgba(49, 162, 76, 0.1);
    color: var(--success);
    border-color: rgba(49, 162, 76, 0.2);
}

.alert-error {
    background: rgba(221, 72, 59, 0.1);
    color: var(--error);
    border-color: rgba(221, 72, 59, 0.2);
}

/* Footer */
footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-light);
    padding: 40px 0;
    margin-top: 60px;
    text-align: center;
    font-size: 13px;
    color: var(--text-tertiary);
}

.ecosystem-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.ecosystem-link {
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    padding: 4px 0;
    border-bottom: 2px solid transparent;
    transition: all 0.2s;
}

.ecosystem-link.otplogin {
    color: var(--otpLogin-accent);
    border-bottom-color: var(--otpLogin-accent);
}

.ecosystem-link.tggo {
    color: var(--tggo-accent);
}

.ecosystem-link.tggo:hover {
    border-bottom-color: var(--tggo-accent);
}

.ecosystem-link.tgdrive {
    color: var(--tgdrive-accent);
}

.ecosystem-link.tgdrive:hover {
    border-bottom-color: var(--tgdrive-accent);
}

.ecosystem-link.storetg {
    color: var(--storetg-accent);
}

.ecosystem-link.storetg:hover {
    border-bottom-color: var(--storetg-accent);
}

/* Loading state */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

/* Responsive */
@media (max-width: 768px) {
    section {
        padding: 40px 0;
    }

    .hero {
        padding: 60px 0 40px;
    }

    section h2 {
        margin-bottom: 30px;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .code-input-group {
        gap: 6px;
    }

    .code-digit {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 24px;
    }

    .hero .tagline {
        font-size: 16px;
    }

    .hero .description {
        font-size: 14px;
    }

    .hero-actions {
        gap: 8px;
    }

    button, .btn {
        padding: 9px 18px;
        font-size: 14px;
    }

    .code-digit {
        width: 36px;
        height: 36px;
        font-size: 16px;
    }
}

@media (prefers-color-scheme: dark) {
    :root {
        --text-primary: #ffffff;
        --text-secondary: #b0b0b0;
        --text-tertiary: #808080;
        --bg-primary: #212121;
        --bg-secondary: #2e2e2e;
        --bg-tertiary: #383838;
        --border: #3a3a3a;
        --border-light: #353535;
    }

    header {
        background-color: rgba(33, 33, 33, 0.95);
    }
}