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CSS

Sébastien Merour
publié le 13/06/2020 à 16h15 | modifé le 13/06/2020 à 19h00
Catégorie : LangagesCommentaires (3298)
CSS
Description

Le CSS (Cascading Styles Sheets) est un langage informatique permettant de décrire le style, la présentation d'un document HTML. Là où le HTML va se contenter de structurer un document, le CSS va prendre en charge le style, la mise en page d'une page web.

En réalité, le HTML n'a jamais eu besoin du langage CSS pour être exécuté sur un navigateur web. Cependant, le CSS est devenu rapidement une nécessité afin de séparer ce qui relève purement et simplement de la structure d'une page web (c'est le rôle du HTML), de ce qui relève de la mie en page (formes, couleurs, polices de caractères....).

Le style d'une page web peut être défini de 3 façons :

-soit directement dans la page HTML (avec par exemple la balise style, située dans la partie HEAD de la page)

-soit en mode inline (exemple : utilisation de la balise strong pour mettre en gras un texte)

-soit grâce à un fichier CSS, référencé dans la section HEAD de la page.

Il est évident qu'il est préférable d'utiliser la 3ème méthode. En effet : imaginons qu'un développeur souhaite modifier complètement le design d'un site web, sans pour autant modifier la structure des pages web. C'est là que le fichier CSS a son intérêt : le développeur pourra modifier le style du site en ne modifiant que le fichier CSS du site. Ce sera d'autant plus utile si le site web contient de très nombreuses pages.

Il est possible également qu'une page web ou qu'un site fasse appel à plusieurs fichiers CSS. Par exemple, il est fréquent de voir un fichier CSS différent pour chaque taille d'écran, afin de rendre un site 100% responsive.

Par ailleurs, le CSS est devenu de plus en plus puissant au fil des années. Désormais, le CSS permet d'afficher par exemple des animations, ou des graphiques particulièrement complexes.

Les sélecteurs

Le principe du CSS repose sur la sélection : on sélecte un élément (par exemple un type de balise, ou bien une balise possédant un identifiant) pour lui appliquer un style. On pourra par exemple appliquer une couleur rouge pour tous les titres de type H3.

Box Model

Tous les élements HTML (une image, un paragraphe, un formulaire...) peut être considéré comme une boîte. Pour définir cette boîte, on utilise 4 élements :

- Margin (Marge - l'espace qui est en dehors de la bordure)

- Border (Bordure - la bordure qui est autour du padding)

- Padding (Ecart - l'écart entre le contenu et la bordure)

- Content (Contenu - par exemple le texte et les images)

Grid

Grid est un principe CSS permettant d'afficher un Layout en mode "grille". Le développeur peut utiliser ce principe pour positionner des éléments dans une grille, en faisant varier par exemple la taille de chaque case, ou l'orientation de chaque rangée, etc...

Pour afficher un layout en mode Grid, il est nécessaire d'insérer l'instruction display: grid

Flexbox

Auparavant, nous avions 4 formats de Layouts possibles :

- Block, pour les sections d'une page

- Inline, pour le texte

- Table, pour afficher un tableau

- Positioned, pour positionner explicitement un élément.

L'arrivée du concept du Flexbox facilite la création de layout, sans avoir à utiliser les notions de float ou de position.

Pour activer la notion de flexbox sur un élément, il est nécessaire d'appliquer un affichage flex avec l'instruction display: flex

Les proprités d'un conteneur Flex sont les suivantes :

flex-direction

flex-wrap

flex-flow

justify-content

align-items

align-content

Fonctionnalités
Style / Mise en page
Date de création
17/12/1996
Créateur
W3C
Dernière version
3
Langage
CSS
Liens
Aux dernières nouvelles
Depuis 2010, CSS est censé évoluer vers sa version 4. Mais suite au succès de HTML 5 couplé avec CSS 3, il est possible que CSS 4 ne voit jamais le jour, où bien que la notion de version (5 pour HTML et 3 pour CSS) disparaisse, pour devenir des langages en constante évolution.

3298 Commentaire(s)
  1. user
    WalterFep
    08/07/2025 à 13h26  commentaire modifé
    Greetings! We present to your attention innovative device for dynamic balancing of rotating equipment - portable balancing device Balanset-1A. Official product page: https://vibromera.eu/shop/889/ Professional vibration analysis set Application Areas Balanset-1A is widely used for imbalance elimination of diverse kinds rotor units: Production Mechanisms: Ventilation Units - industrial, exhaust, duct. Pumping Equipment - centrifugal, oil. Motors - asynchronous. Turbines - steam. Compression Equipment - centrifugal. Machine Tools: Tool Spindles - grinding. Grinding Wheels. Shafts of paper machines. Agro Equipment: Choppers. Vegetation Shredders. Grinding Equipment for fertilizers. Specialized Machinery: Separators - laboratory. Blowers. Grinding Equipment. Cardan Shafts. Rotor balancing in field conditions Technical Specifications Main Parameters: Balancing planes: 1-2. Rotation frequency range: 200 to 15,000 revolutions per minute. Phase determination accuracy: ±1°. Vibration error: ±5%. Number of measurement channels: 2. Vibration velocity measurement range: 0.1 to 300 mm/s. Power: From computer USB port. Equipment mass: 4 kg. System Capabilities: Automatic counting of compensating masses. Results archiving of operations. Permissible values computation according to ISO 1940. Spectral analysis of vibration. Graphical display in real time. Split-weight calculator. Index balancing of mandrels. Supply Composition Standard Configuration: USB measurement module (1 pc.) - delivers data transfer between measurement system and PC. Accelerometers (2 pcs.) - Output signal: 100 mV/g. Bandwidth: 0.5-10,000 Hz. Installation: threaded stud. Accelerometer with magnetic base Optical tachometer (1 pc.) - Operating distance: up to 1.5 m. Remote sensing for operator protection. Digital RPM sensor Magnetic mount for phase sensor (1 pc.) - Holding force: 60 kgf. Adjustable positioning for optimal alignment. Adjustable sensor mount Precision scales up to 500 g (1 pc.) - Precision: 0.01 g. Essential for correct weight calculation. Balancing software Balanset-1A - User-friendly interface. Computer software. Multilingual interface. Balancing program settings Carrying case (1 pc.) - Durable construction. Foam inserts for secure storage. User manual - Detailed instructions. Clear methodology. Cable set - Reliable noise-resistant wiring. Strong Points of Balanset-1A Technical Advantages: ? High Accuracy - Advanced methods of digital filtering guarantee consistent accuracy. ? Mobility - Light weight enables in-place adjustment without disassembly. ? Wide Capabilities - Suitable for various rotors from small fans to large turbines. ? Simple Operation - Clear controls bypasses complex learning. Workshop balancing setup Economic Advantages: ? Savings on repairs through timely diagnostics - significant reduction of unexpected breakdowns. ? Service Life Increase by 50-200% - properly maintained rotors operates reliably. ? Energy Efficiency by 5-15% - balanced rotors consume less power. ? Short ROI Period - from 3 to 12 months depending on operational scale. Additional Services We offer: Specialist Preparation - theoretical sessions in our facility. Advanced training covers complete methodology. Technical Support - 24/7 guidance. Email support for quick problem solving. Metrological Support - periodic verification to guarantee reliability. Equipment Rental - perfect for short-term needs. Monthly hire periods available. Industrial equipment balancing Pricing Current Pricing: Balanset-1A Portable Balancer & Vibration Analyzer: €1,751.00 Balanset-1A OEM Version: €1,561.00 Additional Vibration Sensor: €90.00 Optical Sensor (Laser Tachometer): €124.00 Magnetic Stand 60 kgf: €46.00 Reflective Tape: €10.00 Professional balancing equipment Shipping Conditions: Lead time: from 3 days. Warranty: 24 months comprehensive coverage. Settlement: 50/50. Delivery: international shipping via courier service. Why We Stand Out Official Supplier - factory warranty with comprehensive backup. Expert Engineers with deep knowledge in predictive maintenance. Full Service - from sales to service and education. Ready Stock - fast shipment for common configurations. Custom Conditions for regular customers including special pricing. Full vibration analysis set At your service, Technical support team P.S. Schedule a show of the equipment right now and get special conditions!

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    WalterFep
    08/07/2025 à 09h43  commentaire modifé
    Good Day! We have the honor to propose high-tech device for vibration adjustment of rotor machines - portable balancing device Balanset-1A. Official product page: https://vibromera.eu/shop/889/ Full balancing system Fields of Use Balanset-1A is actively applied for vibration adjustment of diverse kinds rotating equipment: Industrial Machinery: Ventilation Systems - manufacturing, exhaust, duct. Pumping Equipment - gear, oil. Electric Motors - DC motors. Turbines - hydraulic. Compressors - centrifugal. Machine Tools: Tool Spindles - milling. Grinding Wheels. Roll Mechanisms of rolling mills. Agro Equipment: Choppers. Mulchers. Crushing Units for grain. Specialized Machinery: Separators - industrial. Air Blowers. Mills. Drive Shafts. Rotor balancing in field conditions Specifications Main Parameters: Balancing planes: 1-2. Frequency range: 200 to 15,000 rpm. Phase determination accuracy: ±1°. Vibration measurement precision: ±5%. Measurement channels: 2. Vibration velocity measurement range: 0.1 to 300 mm/s. Power source: USB powered. Total weight: 4 kg. Functional Capabilities: Automatic calculation of balancing weights. Database of operations. Standards determination according to ISO 1940. Spectral analysis of vibration. Graphics in diagram form. Correction mass distribution. Eccentricity compensation of mandrels. Supply Composition Standard Configuration: USB measurement module (1 pc.) - provides data transfer between measurement system and PC. Vibration sensors (2 pcs.) - Output signal: 100 mV/g. Frequency range: 0.5-10,000 Hz. Attachment: adhesive mounting. Accelerometer with magnetic base Optical tachometer (1 pc.) - Operating distance: up to 1.5 m. Remote sensing for safe operation. Laser tachometer MS2234 Holder for phase sensor (1 pc.) - Pull force: 60 kgf. Variable angles for best measurement. Professional magnetic stand Precision scales up to 500 g (1 pc.) - Precision: 0.01 g. Required for accurate mass determination. Software Balanset-1A - User-friendly interface. PC-based. Multilingual interface. Balanset software interface Carrying case (1 pc.) - Durable construction. Cushioned interior for safe transport. User manual - Full documentation. Practical examples. Cable set - High-quality interference-free connections. Strong Points of Balanset-1A Technical Advantages: ? Precision Measurements - Modern algorithms of signal processing ensure consistent accuracy. ? Mobility - Light weight allows on-site balancing without disassembly. ? Versatility - Works with various rotors from miniature spindles to massive shafts. ? User Convenience - User-friendly software eliminates need for special training. Workshop balancing setup Economic Advantages: ? Cost Reduction on operation through timely diagnostics - up to 70% of unplanned downtime. ? Durability Enhancement by 50-200% - vibration-free operation operates reliably. ? Energy Efficiency by 5-15% - balanced rotors save electricity. ? Short ROI Period - from 3 to 12 months depending on usage intensity. Support We offer: Operator Training - theoretical sessions in our facility. Advanced training covers complete methodology. Technical Support - remote help. Email support for immediate help. Certification - periodic verification to guarantee reliability. Device Leasing - ideal for short-term needs. Monthly rental options available. Professional vibration analysis Price Information Current Pricing: Balanset-1A Portable Balancer & Vibration Analyzer: €1,751.00 Balanset-1A OEM Version: €1,561.00 Additional Vibration Sensor: €90.00 Optical Sensor (Laser Tachometer): €124.00 Magnetic Stand 60 kgf: €46.00 Reflective Tape: €10.00 Multi-channel vibration analyzer Delivery Terms: Lead time: from 3 days. Warranty: 24 months complete protection. Payment terms: negotiable. Shipping: worldwide via reliable carriers. Why Choose Us Official Supplier - original equipment with complete service. Certified Specialists with years of expertise in rotor balancing. Complete Service Cycle - from sales to maintenance and education. Ready Stock - quick delivery for common configurations. Custom Conditions for large orders including special pricing. Full vibration analysis set At your service, Professional experts group P.S. Schedule a show of the equipment right now and learn about promotions!

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    08/07/2025 à 07h24  commentaire modifé
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