:root{--color-primary: #007AFF;--color-primary-dark: #0051D5;--color-text: #1D1D1F;--color-text-light: #6E6E73;--color-bg: #FFFFFF;--color-bg-light: #F5F5F7;--color-border: #D1D1D6;--color-success: #34C759;--color-warning: #FF9500;--color-error: #FF3B30;--font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", system-ui, sans-serif;--spacing-xs: .5rem;--spacing-sm: 1rem;--spacing-md: 1.5rem;--spacing-lg: 2rem;--spacing-xl: 3rem;--spacing-2xl: 4rem;--spacing-3xl: 6rem;--radius: 12px;--radius-lg: 16px}.ielts-tip-page{min-height:100vh;background:var(--color-bg-light);font-family:var(--font-family);-webkit-font-smoothing:antialiased;color:var(--color-text);line-height:1.7}.ielts-tip-icon{width:20px;height:20px}.ielts-tip-header{background:var(--color-bg);border-bottom:2px solid var(--color-border);padding:var(--spacing-lg) var(--spacing-md);position:sticky;top:0;z-index:100;box-shadow:0 2px 8px #0000000d}.ielts-tip-btn-back{display:inline-flex;align-items:center;gap:var(--spacing-xs);background:transparent;border:none;color:var(--color-primary);font-size:1rem;font-weight:600;cursor:pointer;padding:var(--spacing-xs) 0;margin-bottom:var(--spacing-md);transition:opacity .2s}.ielts-tip-btn-back:hover{opacity:.7}.ielts-tip-title{font-size:3rem;font-weight:900;line-height:1.1;margin:0 0 var(--spacing-xs) 0;letter-spacing:-.02em;color:var(--color-text)}.ielts-tip-subtitle{font-size:1.25rem;font-weight:500;color:var(--color-text-light);margin:0}.ielts-tip-main{padding:var(--spacing-2xl) var(--spacing-md)}.ielts-tip-container{max-width:900px;margin:0 auto}.ielts-tip-section{margin-bottom:var(--spacing-3xl)}.ielts-tip-section-title{font-size:2.5rem;font-weight:900;line-height:1.2;margin:0 0 var(--spacing-xl) 0;letter-spacing:-.02em;color:var(--color-text)}.ielts-tip-content-box{background:var(--color-bg);border-radius:var(--radius-lg);padding:var(--spacing-xl);border:2px solid var(--color-border)}.ielts-tip-content-item{margin-bottom:var(--spacing-xl)}.ielts-tip-content-item:last-child{margin-bottom:0}.ielts-tip-content-label{font-size:1.25rem;font-weight:800;margin:0 0 var(--spacing-md) 0;color:var(--color-text)}.ielts-tip-text{font-size:1.125rem;line-height:1.9;margin:0;color:var(--color-text);font-weight:400}.ielts-tip-examples{display:flex;flex-direction:column;gap:var(--spacing-xl)}.ielts-tip-example{background:var(--color-bg);border-radius:var(--radius-lg);border:2px solid var(--color-border);overflow:hidden}.ielts-tip-example-header{display:flex;align-items:center;justify-content:space-between;padding:var(--spacing-md) var(--spacing-lg);background:var(--color-bg-light);border-bottom:2px solid var(--color-border)}.ielts-tip-example-number{font-size:1rem;font-weight:800;color:var(--color-text)}.ielts-tip-example-type{font-size:.875rem;font-weight:800;padding:var(--spacing-xs) var(--spacing-md);background:var(--color-primary);color:#111;border-radius:var(--radius);text-transform:uppercase;letter-spacing:.05em}.ielts-tip-example-body{padding:var(--spacing-lg);display:flex;flex-direction:column;gap:var(--spacing-lg)}.ielts-tip-example-part{display:flex;flex-direction:column;gap:var(--spacing-sm)}.ielts-tip-example-label{font-size:1rem;font-weight:800;color:var(--color-text);margin:0 0 var(--spacing-xs) 0}.ielts-tip-example-text-vi{font-size:1.125rem;line-height:1.8;color:var(--color-text);margin:0;font-weight:500}.ielts-tip-example-text-en{font-size:1rem;line-height:1.8;color:var(--color-text-light);margin:0;font-style:italic}.ielts-tip-mistakes{display:flex;flex-direction:column;gap:var(--spacing-lg)}.ielts-tip-mistake{background:var(--color-bg);border-radius:var(--radius-lg);border:2px solid var(--color-border);padding:var(--spacing-lg);display:flex;gap:var(--spacing-lg);align-items:flex-start}.ielts-tip-mistake-number{width:40px;height:40px;background:var(--color-error);color:#111;border-radius:var(--radius);display:flex;align-items:center;justify-content:center;font-size:1.125rem;font-weight:800;flex-shrink:0}.ielts-tip-mistake-content{flex:1;display:flex;flex-direction:column;gap:var(--spacing-sm)}.ielts-tip-mistake-text-vi{font-size:1.125rem;line-height:1.8;color:var(--color-text);margin:0;font-weight:500}.ielts-tip-mistake-text-en{font-size:1rem;line-height:1.8;color:var(--color-text-light);margin:0;font-style:italic}.ielts-tip-error{display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;padding:var(--spacing-lg);text-align:center}.ielts-tip-error h2{font-size:2rem;font-weight:800;margin-bottom:var(--spacing-lg);color:var(--color-text)}@media(max-width:768px){.ielts-tip-header{padding:var(--spacing-md)}.ielts-tip-title{font-size:2rem}.ielts-tip-subtitle{font-size:1.125rem}.ielts-tip-main{padding:var(--spacing-xl) var(--spacing-md)}.ielts-tip-section-title{font-size:2rem}.ielts-tip-content-box{padding:var(--spacing-lg)}.ielts-tip-text{font-size:1rem}.ielts-tip-example-body{padding:var(--spacing-md)}.ielts-tip-mistake{flex-direction:column;gap:var(--spacing-md)}}@media(max-width:480px){.ielts-tip-title,.ielts-tip-section-title{font-size:1.75rem}.ielts-tip-content-box{padding:var(--spacing-md)}}